Bridge Design Manual M 23 50 Chapter 10 Signs, Barriers,Approach Slabs, And Utilities 2001 3.2 TL Chapter10

User Manual: 2001 3.2 TL

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Chapter 10 Signs, Barriers,
Approach Slabs, and Utilities

Contents

10.1

Sign and Luminaire Supports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
10.1.1
Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
10.1.2
Bridge Mounted Signs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3
10.1.3
Monotube Sign Structures Mounted on Bridges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7
10.1.4
Monotube Sign Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-8
10.1.5
Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-12
10.1.6
Truss Sign Bridges: Foundation Sheet Design Guidelines . . . . . . . . . . . . . . . . . . . . . 10-15

10.2

Bridge Traffic Barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.1
General Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.2
Bridge Railing Test Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.3
Available WSDOT Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.2.4
Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10-16
10-16
10-17
10-17
10-21

10.3

At Grade Concrete Barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.3.1
Differential Grade Concrete Barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.3.2
Traffic Barrier Moment Slab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.3.3
Precast Concrete Barrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10-26
10-26
10-27
10-31

10.4

Bridge Traffic Barrier Rehabilitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.4.1
Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.4.2
Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.4.3
Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.4.4
WSDOT Bridge Inventory of Bridge Rails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.4.5
Available Retrofit Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.4.6
Available Replacement Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10-32
10-32
10-32
10-32
10-33
10-33
10-34

10.5

Bridge Railing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-35
10.5.1
Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-35
10.5.2
Railing Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-35

10.6

Bridge Approach Slabs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.6.1
Notes to Region for Preliminary Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.6.2
Bridge Approach Slab Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.6.3
Bridge Approach Slab Detailing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.6.4
Skewed Bridge Approach Slabs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.6.5
Approach Anchors and Expansion Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.6.6
Bridge Approach Slab Addition or Retrofit to Existing Bridges . . . . . . . . . . . . . . . . .
10.6.7
Bridge Approach Slab Staging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10.7

Traffic Barrier on Bridge Approach Slabs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-43
10.7.1
Bridge Approach Slab over Wing Walls, Cantilever Walls or Geosynthetic Walls . . . . . 10-43
10.7.2
Bridge Approach Slab over SE Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-45

10.8

Utilities Installed with New Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.8.1
General Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.8.2
Utility Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.8.3
Box/Tub Girder Bridges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.8.4
Traffic Barrier Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.8.5
Conduit Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.8.6
Utility Supports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

WSDOT Bridge Design Manual M 23-50.17
June 2017

10-36
10-36
10-37
10-37
10-38
10-39
10-40
10-42

10-46
10-46
10-49
10-51
10-51
10-52
10-52

Page 10-i

Contents

10.9

Utility Review Procedure for Installation on Existing Bridges . . . . . . . . . . . . . . . . . . 10-54
10.9.1
Utility Review Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-55

10.10 Drilled Anchors For Permanent Attachments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-57
10.11 Drainage Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-58
10.12 Bridge Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.12.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.12.2 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.12.3 Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10-59
10-59
10-59
10-60

10.13 Temporary Bridges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.13.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.13.2 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.13.3 NBI Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.13.4 Submittal Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10-61
10-61
10-61
10-62
10-62

10.14 Bridge Standard Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-64
10.15 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-66

Page 10-ii

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

Signs, Barriers,
Approach Slabs, and Utilities

10.1

Sign and Luminaire Supports

10.1.1

Loads
A. General
The reference used in developing the following office criteria is the
AASHTO LRFD Standard Specifications for Structural Supports for Highway
Signs, Luminaires, and Traffic Signals, First Edition dated 2015 and shall be the
basis for analysis and design.
B. Design Life (Section 11.5, AASHTO 2015)
1. An Infinite life fatigue design will be used for luminaire supports, overhead
sign structures, and traffic signal structures. The number of cycles a structure
must withstand will be based on the ADTT of a 75 year design life with
each truck inducing one cycle in accordance with AASHTO LRFD Standard
Specifications for Structural Supports for Highway Signs, Luminaires, and
Traffic Signals First Edition, dated 2015 including interims.
2. Roadside sign structures will use a 10 year design life.
C. Dead Loads
Sign (including panel and wind beams, does not include vert. bracing) 3.25 lbs/ft2
Luminaire (effective projected area of head = 3.3 sq ft)
60 lbs/each
Fluorescent Lighting 3.0 lbs/ft
Standard Signal Head 60 lbs/each
Mercury Vapor Lighting 6.0 lbs/each
Sign Brackets Calc.
Structural Members
Calc.
5 foot wide maintenance walkway
(Including mounting brackets and handrail)
160 lbs/ft
Signal Head w/3 lenses
(Effective projected area with backing plate = 9.2 sq ft)
60 lbs/each
D. Live Load
A live load consisting of a single load of 500 lb distributed over 2.0 feet
transversely to the member shall be used for designing members for walkways and
platforms. The load shall be applied at the most critical location where a worker or
equipment could be placed, see AASHTO 2015, Section 3.6.
E. Wind Loads
A 3 second gust wind speed shall be used in the AASHTO wind pressure equation.
The 3 second wind gust map in AASHTO is based on the wind map in ANSI/
ASCE 7-10.

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Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

Basic wind speed of 115 mph shall be used in computing design wind pressure
using equation 3.8.1-1 of AASHTO Section 3.8.1. This is based on the high risk
category with a mean recurrence intended of 1700 years per AASHTO Table 3.8-1.
The Alternate Method of Wind Pressures given in Appendix C of the AASHTO
2009 Specifications shall not be used.
F. Fatigue Design
Fatigue design shall conform to AASHTO Section 11 with the exception of tube
shape. AASHTO does not provide fatigue calculations for shapes with less than 8
sides. Therefore, calculating the Constant Amplitude Fatigue Threshold, DT (Table
11.9.3.1-2, AASHTO 2015) was taken to be the larger outer flat to flat distance
of the rectangular tube. Fatigue Categories are listed in Table 11.6-1. Overhead
Cantilever and Bridge Sign and signal structures, high mast luminaires (HMLT),
poles, and bridge mounted sign brackets shall conform to the following fatigue
categories.
Fatigue Category I: Overhead cantilever sign structures (maximum span of 35 feet
and no VMS installation), overhead sign bridge structures, high level (high mast)
lighting poles 80 feet or taller in height, bridge-mounted sign brackets, and all
signal bridges. Gantry or pole structures used to support sensitive electronic
equipment (tolling, weigh-in-motion, transmitter/receiver antennas, transponders,
etc.) shall be designed for Fatigue Category I, and shall also meet any deflection
limitations imposed by the electronic equipment manufacturers.
Fatigue Category II: For structures not explicitly falling into Category I or III.
Fatigue Category III: Lighting poles 50 feet or less in height with rectangular,
square or non-tapered round cross sections, and overhead cantilever traffic signals
at intersections (maximum cantilever length 65 feet).
Sign bridges, cantilever sign structures, signal bridges, and overhead cantilever
traffic signals mounted on bridges shall be either attached to substructure elements
(e.g., crossbeam extensions) or to the bridge superstructure at pier locations.
Mounting these features to bridges as described above will help to avoid resonance
concerns between the bridge structure and the signing or signal structure.
The “XYZ” limitation shown in Table 10.1.4-2 shall be met for Monotube
Cantilevers. The “XYZ” limitation consists of the product of the sign area (XY)
and the arm from the centerline of the posts to the centerline of the sign (Z). See
Appendix 10.1-A2-1 for details.
G. Ice and Snow Loads
A 3 psf ice load may be applied around all the surfaces of structural supports,
horizontal members, and luminaires, but applied to only one face of sign panels
(Section 3.7, AASHTO 2015).
Walk-through VMS shall not be installed in areas where appreciable snow loads
may accumulate on top of the sign, unless positive steps are taken to prevent snow
build-up.

Page 10-2

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

10.1.2

Signs, Barriers, Approach Slabs, and Utilities

Bridge Mounted Signs
A. Vertical Clearance
All new signs mounted on bridge structures shall be positioned such that the
bottom of the sign or lighting bracket does not extend below the bottom of the
bridge as shown in Figure 10.1.2-1. The position of the sign does not need to allow
for the future placement of lights below the sign. If lights are to be added in the
future they will be mounted above the sign. To ensure that the bottom of the sign
or lighting bracket is above the bottom of the bridge, the designer shall maintain
at least a nominal 2 inch dimension between the bottom of the sign or lighting and
the bottom of the bridge to account for construction tolerances and bracket arm sag.
Maximum sign height shall be decided by the Region. If the structure is too high
above the roadway, then the sign shall not be placed on the structure.
Bridge mounted sign brackets shall be designed to account for the weight of added
lights, and for the wind effects on the lights to ensure bracket adequacy if lighting
is attached in the future.









Sign Vertical Clearance

Figure 10.1.2-1


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Page 10-3

Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

B. Geometrics
1. Signs shall be installed at approximate right angles to approaching motorists.
For structures above a tangent section of roadway, signs shall be designed
to provide a sign skew within 5° from perpendicular to the lower roadway
(see Figure 10.1.2-2).










Sign Skew on Tangent Roadway
Figure 10.1.2-2

2. For structures located on or just beyond a horizontal curve of the lower
roadway, signs shall be designed to provide a sign chord skew within 5°
from perpendicular to the chord-point determined by the approach speed (see
Figure 10.1.2-3).

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WSDOT Bridge Design Manual M 23-50.17
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Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

3. The top of the sign shall be level.








 

 
 







Sign Skew on Curved Roadway
Figure 10.1.2-3





Figure 10.1.2-4

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Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

C. Aesthetics
1. The support structure shall not extend beyond the limits of the sign unless the
extension is unavoidable.
2. The sign support shall be detailed in such a manner that will permit the sign
and lighting bracket to be installed level.
3. When the sign support will be exposed to view, special consideration is
required in determining member sizes and connections to provide as pleasing
an appearance as possible.
D. Sign Placement
1. Signs shall not be placed under bridge overhangs. This causes partial shading
or partial exposure to the elements and problems in lifting the material into
position and making the required connections. Signs shall never be placed
directly under the drip‑line of the structure. These conditions may result in
uneven fading, discoloring, and difficulty in reading.



2. A minimum of 2 inches of clearance shall be provided between back side of the
sign support and edge of the bridge. See Figure 10.1.2-5.







Sign Horizontal Location
Figure 10.1.2-5

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Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

E. Installation
1. Resin bonded anchors or cast-in-place ASTM F593 Group 1 Condition A
anchor rods shall be used to install the sign brackets on the structure. Size
and minimum installation depth shall be given in the plans or specifications.
The resin bonded anchors shall be installed normal to the concrete surface.
Resin bonded anchors shall not be placed through the webs or flanges of
prestressed or post-tensioned girders unless approved by the WSDOT Bridge
Design Engineer. Resin bonded anchors shall not be used at overhead locations
other than with horizontal hole/anchor alignment.
2. Bridge mounted sign structures shall not be placed on bridges with steel
superstructures unless approved by the WSDOT Bridge Design Engineer.
F. Installing/Replacing New Sign on Existing Bracket Supports
When installing a new sign on existing bracket supports, the following shall
be required:
1. All hardware shall be replaced per the current Standard Specifications.
2. The new sign area shall not exceed the original designed sign area.
3. The inspection report for the bracket shall be reviewed to ensure that the
supports are in good condition. If there is not an inspection report, then an
inspection shall be performed on the bracket.
10.1.3

Monotube Sign Structures Mounted on Bridges
A. Design Loads
Design loads for the supports of the Sign Bridges shall be calculated based on
assuming a 12‑foot‑deep sign over the entire roadway width, under the sign bridge,
regardless of the sign area initially placed on the sign bridge. For Cantilever design
loads, guidelines specified in Section 10.1.1 shall be followed. The design loads
shall follow the same criteria as described in Section 10.1.1. Loads from the sign
bridge shall be included in the design of the supporting bridge.
In cases where a sign structure is mounted on a bridge, the sign structure, from
the anchor bolt group and above, shall be designed to AASHTO LRFD Standard
Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic
Signals First Edition, dated 2015 including interims. The concrete the anchor bolt
group and the connecting elements to the bridge structure shall be designed to the
specifications in this manual and AASHTO LRFD. The appropriate LRFD load
combinations from the sign structure design code shall be used with the same
LRFD load combinations from the bridge design code.
B. Vertical Clearance
Vertical clearance for Monotube Sign Structures shall be 20′-0″ minimum from
the bottom of the lowest sign to the highest point in the traveled lanes. See
Appendix 10.1-A1-1, 10.1-A2-1, and 10.1-A3-1 for sample locations of Minimum
Vertical Clearances.

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Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

C. Geometrics
Sign structures shall be placed at approximate right angles to approaching
motorists. Dimensions and details of sign structures are shown in the Standard
Plans G-60.10, G-60.20, G-60.30, G-70.10, G-70.20, G-70.30 and Appendix
10.1-A1-1, 10.1-A1-2, and 10.1-A1-3 and 10.1-A2-1, 10.1-A2-2, and 10.1-A23. When maintenance walkways are included, refer to Standard Plans G-95.10,
G-95.20, G-95.30.
10.1.4

Monotube Sign Structures
A. Sign Bridge Conventional Design
Table 10.1.4-1 provides the conventional structural design information to be used
for a Sign Bridge Layout, Appendix 10.1-A1-1; along with the Structural Detail
sheets, which are Appendix 10.1-A1-2 and Appendix 10.1-A1-3; General Notes,
Appendix 10.1-A5-1; and Miscellaneous Details, Appendix 10.1-A5-2.
B. Cantilever Conventional Design
Table 10.1.4-2 provides the conventional structural design information to be used
for a Cantilever Layout, Appendix 10.1-A2-1; along with the Structural Detail
sheets, which are Appendix 10.1-A2-2 and Appendix 10.1-A2-3; General Notes,
Appendix 10.1-A5-1; and Miscellaneous Details, Appendix 10.1-A5-2.

Page 10-8

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10
SPAN
LENGTH
"S"
LESS
THAN
60'-0"
60'-0"
TO
75'-0"
+75'-0"
TO
90'-0"
+90'-0"
TO
105'-0"
+105'-0"
TO
120'-0"
+120'-0"
TO
135'-0"
+135'-0"
TO
150'-0"
+150'-0"
TO
165'-0"
+165'-0"
TO
180'-0"

Signs, Barriers, Approach Slabs, and Utilities

STANDARD MONOTUBE SIGN BRIDGES
POSTS ¦
BEAM A ¦
"H"
"A" "B" "T1" "L1" "B" "C" "T2"
30'-0"
OR 1'-6" 2'-0" ½" 6'-0" 2'-0" 2'-0" ½"
LESS
30'-0"
OR 1'-6" 2'-3" ⅝" 6'-0" 2'-3" 2'-0" ⅝"
LESS
30'-0"
OR 1'-6" 2'-3" ⅝" 6'-0" 2'-3" 2'-0" ⅝"
LESS
30'-0"
OR 1'-9" 2'-6" ⅝" 6'-0" 2'-6" 2'-3" ⅝"
LESS
30'-0"
OR 1'-9" 2'-6" ⅝" 6'-0" 2'-6" 2'-3" ⅝"
LESS
30'-0"
OR 2'-0" 2'-6" ⅝" 6'-0" 2'-6" 2'-6" ⅝"
LESS
30'-0"
OR 2'-0" 2'-6" ⅝" 6'-0" 2'-6" 2'-6" ⅝"
LESS
30'-0"
OR 2'-0" 2'-8" ¾" 6'-0" 2'-8" 2'-8" ⅝"
LESS
30'-0"
OR 2'-0" 2'-8" ¾" 6'-0" 2'-8" 2'-8" ⅝"
LESS

BEAM B ¦
BEAM C ¦
BEAM D ¦
CAMBER
"L2" "B" "C" "T2" "L3" "B" "C" "T2"
13'-0"
0'-0" 2'-0" 2'-0" ½" TO 2'-0" 2'-0" ½"
2¾"
48'-0"
9'-0"
30'-0"
TO 2'-3" 2'-0" ⅝" TO 2'-3" 2'-0" ⅝"
3¾"
14'-0"
35'-0"
14'-0"
35'-0"
TO 2'-3" 2'-0" ⅝" TO 2'-3" 2'-0" ⅝"
5"
19'-0"
40'-0"
19'-0"
TO 2'-6" 2'-3" ⅝" 40'-0" 2'-6" 2'-3" ⅝"
6"
26'-6"
26'-6"
TO 2'-6" 2'-3" ⅝" 40'-0" 2'-6" 2'-3" ⅝"
7½"
34'-0"
34'-0"
TO 2'-6" 2'-6" ⅝" 40'-0" 2'-6" 2'-6" ⅝"
8½"
41'-6"
41'-6"
TO 2'-6" 2'-6" ⅝" 40'-0" 2'-6" 2'-6" ⅝"
10½"
49'-0"
18'-5"
27'-0" 2'-8" 2'-8" ⅝" TO 2'-8" 2'-8" ⅝" 48'-0" 2'-8" 2'-8" ⅝"
13¾"
25'-6"
22'-6"
30'0" 2'-8" 2'-8" ⅝" TO 2'-8" 2'-8" ⅝" 48'-0" 2'-8" 2'-8" ⅝"
15¾"
30'-0"

SPAN
BOLTED SPLICE #1
BOLTED SPLICE #2
BOLTED SPLICE #3
LENGTH
POST BASE ¦
L1 TO L2 AND L1 TO L3
L2 TO L3
L3 TO L4
"S" "D1" "S5" "S6" "T3" "T6" "S1" "S2" "S3" "S4" "T4" "T5" "S1" "S2" "S3" "S4" "T4" "T5" "S1" "S2" "S3" "S4" "T4" "T5"
LESS
THAN 1½" 4
4 3" ¾" 5
5
- 2" ⅝" 60'-0"
60'-0"
TO 1¾" 4
4 3" ¾" 6
5
- 2" ⅝" 6
5
- 2¼" ¾" 75'-0"
+75'-0"
TO 1¾" 4
4 3" ¾" 6
5
- 2" ⅝" 6
5
- 2¼" ¾" 90'-0"
+90'-0"
TO 1¾" 4
5 3" 1" 7
6
- 2" ⅝" 7
5
6
4 2½" 1" 105'-0"
+105'-0"
TO 1¾" 4
5 3" 1" 7
6
- 2" ⅝" 7
5
6
4 2½" 1" 120'-0"
+120'-0"
TO
2" 4
5 3" 1" 7
5
7
5 2" ⅝" 7
5
7
5 2½" 1" 135'-0"
+135'-0"
TO
2" 4
5 3" 1" 7
5
7
5 2" ⅝" 7
5
7
5 2½" 1" 150'-0"
+150'-0"
TO
2" 4
5 3" 1" 7
5
7
5 2" ⅝" 7
5
7
5 2½" 1" 7
5
7
5 2½" 1"
180'-0"

MAX
SIGN
AREA
600 SQ.
FT.
700
SQ FT.
800 SQ.
FT.
900 SQ.
FT.
900 SQ.
FT.
900 SQ.
FT.
900 SQ.
FT.
900 SQ.
FT.

¦ NOTE: DENOTES MAIN LOAD CARRYING TENSILE MEMBERS OR TENSION COMPONENTS OF FLEXURAL MEMBERS.

Table 10.1.4-1

WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-9

Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

STANDARD MONOTUBE CANTILEVERS
Span Length

Posts ¦

Beam A ¦

Beam B ¦

"S"

"H"

"A"

"B"

"T1"

"L1"

"B"

"C"

"T2"

"L2"

"B"

"C"

Less Than
20'-0"

30'-0"
or Less

1'-6"

2'-0"

½"

6'-0"

2'-0"

½"

14'-0"

2'-0"

½"

20'-0" to
35'-0"

30'-0"
Or Less

1'-6"

2'-0"

½"

6'-0"

2'-0"

½"

14'-0"
TO
29'-0"

2'-0"

½"

3½"

Span Length

Post Base ¦

Bolted Splice

"T2" Camber

Maximums
Sign
Area

"S"

"D1"

"S5"

"S6"

"T3"

"T6"

"S1"

"S2"

"S3"

"S4"

"T4"

"T5"

"XYZ"

"Z"

Less Than
20'-0"

1½"

¾"

⅝"

194 SQ. 2920
FT.
C.F.

15'-0"

20'-0" to
30'-0"

¾"

2½"

⅝"

330 SQ. 5363
FT.
C.F.

20'-0"

+30'-0" to
35'-0"

¾"

2½"

⅝"

235 SQ. 5924
FT.
C.F.

25'-0"

¦ Note: Denotes Main Load Carrying Tensile Members Or Tension Components Of Flexural Members.

Table 10.1.4-2

C. Balanced Cantilever Conventional Design
Appendix 10.1-A3-1; along with the Structural Detail sheets, Appendix 10.1-A3-2
and 10.1-A3-3, General Notes, Appendix 10.1-A5-1; and Miscellaneous Details,
Appendix 10.1-A5-2, provides the conventional structural design information to
be used for a Balanced Cantilever Layout. Balanced Cantilevers are typically for
VMS sign applications and shall have the sign dead load balanced with a maximum
difference of one-third to two-thirds distribution.
D. VMS Installation
1. VMS units shall not be installed on unbalanced cantilever structures.
2. VMS installation on Sign Bridge structures designed in accordance with
AASHTO 2015 shall be installed in accordance with the following:
a. On spans 120 ft and greater up to two VMS units may be installed with
a maximum weight of 4,000 lbs each. Maintenance walkways may be
installed between VMS units, but may not exceed 160 lbs/ft, or exceed
50 percent of the structure span length.
b. On spans less than 120 ft. up to three VMS units may be installed with
a maximum weight of 4,000 lbs. each. Maintenance walkways may be
installed between VMS units, but may not exceed 160 lbs/ft.
3. The number of VMS installed on Sign Bridge structures designed prior to
AASHTO 2015 shall be reduced by one as defined in D.2-a and b.

Page 10-10

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

E. Monotube Sheet Guidelines
The following guidelines apply when using the Monotube Sign Structure Appendix
10.1-A1-1, 10.1-A1-2, and 10.1-A1-3; 10.1-A2-1, 10.1-A2-2, and 10.1-A2-3;
10.1-A3-1, 10.1-A3-2, and 10.1-A3-3; 10.1-A4-1, 10.1-A4-2, and 10.1-A4-3;
and 10.1-A5-1, 10.1-A5-2, and 10.1-A5-3.
1. Each sign structure shall be detailed to specify:
a. Sign structure base Elevation, Station, and Number.
b. Type of Foundation 1, 2, or 3 shall be used for the Monotube Sign
Structures, unless a non-conventional design is required. The average
Lateral Bearing Pressure for each foundation shall be noted on the
Foundation sheet(s).
c. If applicable, label the Elevation View “Looking Back on Stationing.”
2. Designers shall verify the cross-referenced page numbers and details are
correct.
F. Monotube Quantities
Quantities for structural steel are given in Table 10.1.4-3.
Sign Structure Material Quantities
Cantilever

Sign Bridge

20’ <

20’
to
30’ Balanced 60’ <

60’
to
75’

75’
to
90’

90’
to
105’

105’
to
120’

120’
to
135’

135’
to
150’

Post (plf)

132

176

204

215

267

Base PL (lbs./ea)

537

806

672

735

888

978

1029

Beam, near Post (plf)

152

202

228

240

257

Span Beam (plf)

152

202

228

240

257

Corner Stiff . (lbs./ea set)

209

115

218

272

354

376

425

Splice Pl #1 (lbs/pair)

592

706

578

650

826

1116

1295

Splice Pl #2 (lbs/pair)

730

1002 1002

1116

1295

Splice Pl #3 (lbs/pair)

1295

Brackets (lbs./ea)

6” Hand Hole (lbs./ea)

6” x 11” Hand Hole (lbs./ea)

Anchor Bolt PL (lbs./ea)

175

185

311

326

Cover Plates (lbs./ea)

ASTM A572 GR. 50 or
ASTM 588

150’
to
180’

Sign Structure Steel Quantities
Table 10.1.4-3

WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-11

Signs, Barriers, Approach Slabs, and Utilities

10.1.5

Chapter 10

Foundations
A. Monotube Sign Structure Foundation Types
The foundation type is to be used shall be based on the geotechnical investigation
performed and geotechnical report completed by the geotechnical engineer of
record. Standard foundation designs for standard plan truss-type sign structures
are provided in WSDOT Standard Plans G-60.20 and G-60.30 and G-70.20
and G-70.30. Monotube sign structure foundations are Bridge Design Office
conventional designs and shall be as described in the following paragraphs:
1. Foundation Type 1, is the preferred foundation type. A foundation Type 1
consists of a drilled shaft with its shaft cap. The design of the shaft depths
shown in the Sign Bridge Standard Drawings are based on a lateral bearing
pressure of 2,500 psf. The designer shall check these shaft depths using
AASHTO LRFD methodology. For Type 1 foundation details and shaft
depths see Sign Bridge Standard Drawings 10.1-A4-1 and 10.1-A4-2. The
Geotechnical report for Foundation Type 1 should include the soil friction angle,
soil unit weight, allowable bearing pressure and temporary casing if required.
Temporary casing shall be properly detailed in all Foundation Type 1 sheets if
the Geotechnical Engineer requires them.
2. Foundation Type 2 is an alternate to Type 1 when drilled shafts are not suitable
to the site. Foundation Type 2 is designed for a lateral bearing pressure of
2,500 psf. See Appendix 10.1‑A4‑3 for Foundation Type 2 Bridge Design
Office conventional design information. The designer shall check these shaft
depths using LRFD methodology.
3. Foundation Type 3 replaces the foundation Type 2 for poor soil conditions
where the lateral bearing pressure is between 2,500 psf and 1,500 psf. See
Bridge Standard Drawing 10.1-A4-3 for Type 3 Foundation Bridge Design
Office conventional design information. The designer shall check these shaft
depths using LRFD methodology.
4. Barrier Shape Foundations are foundations that include a barrier shape cap on
the top portion of Foundation Types 1, 2, and 3. Foundation details shall be
modified to include Barrier Shape Cap details. Appendix 10.1-A5-1 details a
single slope barrier.
B. Luminaire, Signal Standard, and Camera Pole Foundation Types
Luminaire foundation options are shown on Standard Plan J-28.30. Signal Standard
and Camera Pole foundation options are provided on Standard Plans J-26.10 and
J-29.10 respectively.
C. Foundation Design
Shaft type foundations constructed in soil for sign bridges, cantilever sign
structures, luminaires, signal standards and strain poles shall be designed in
accordance with the current edition of the AASHTO LRFD Standard Specifications
for Highway Signs, Luminaires, and Traffic Signals; Section 13.6 Drilled Shafts.

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June 2017

Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

No provisions for foundation torsional capacity are provided in Section 10.13 of
the AASHTO LRFD Standard Specifications for Highway Signs, Luminaires, and
Traffic Signals. The following approach can be used to calculate torsional capacity
of sign structure, luminaire, and signal standard foundations:
Torsional Capacity, φTn,
Where:

F
D
φ

Tn = F*tanφD

10.1.5(1)

= Total force normal to shaft surface (kip)
= Diameter of shaft (feet)
= Soil to foundation contact friction angle (degree), use smallest for
variable soils

1. Monotube Sign Structures Foundation Type 1 Design
The standard embedment depth “Z”, shown in the table on Monotube
Sign Structure Standard Drawing 10.1-A4-1, shall be used as a minimum
embedment depth and shall be increased if the shaft is placed on a sloped
surface, or if the allowable lateral bearing pressures are reduced from the
standard 2500 psf. The standard depth assumed that the top 4 feet of the
C.I.P. cap is not included in the lateral resistance (i.e., shaft depth “D” in the
code mentioned above), but is included in the overturning length of the sign
structure. The sign structure shaft foundation GSPs under Section 8-21 in the
RFP Appendix shall be included with all Foundation Type 1 shafts.
2. Monotube Sign Structures Foundation Type 2 and 3
These foundation designs are Bridge Design Office convention and shall not
be adjusted or redesigned. They are used in conditions where a Foundation
Type 1 (shaft) would be impractical due to difficult drilling or construction
and when the Geotechnical Engineer specifies their use. The concept is that
the foundation excavation would maintain a vertical face in the shape of the
Foundation Type 2 or 3. Contractors often request to over-excavate and backfill
the hole, after formwork has been used to construct this foundation type. This is
only allowed with the Geotechnical engineer's approval, if the forming material
is completely removed, and if the backfill material is either CDF or concrete
class 3000 or better.
3. Monotube Sign Structures Non-Conventional Design Foundations
The Geotechnical Engineer of record shall identify conditions where the
foundation types (1, 2, or 3) will not work. In this case, the design forces are
calculated, using the AASHTO LRFD Standard Specifications for Structural
Supports for Highway Signs, Luminaires, and Traffic Signals, and applied
at the bottom of the structure base plate. These forces are then considered
service loads and the non-conventional design foundation is designed with
the appropriate Service, Strength, and Extreme Load Combination Limit
States and current design practices of the AASHTO LRFD and this manual.
Some examples of these foundations are spread footings, columns and shafts
that extend above ground adjacent to retaining walls, or connections to traffic
barriers on bridges. The anchor rod array shall be used from Tables 10.1.4-1
WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-13

Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

and 10.1.4-2 and shall be long enough to develop the rods into the confined
concrete core of the foundation. The rod length and the reinforcement for
concrete confinement, shown in the top four feet of the Foundation Type 1,
shall be used as a minimum.
4. Signal Foundation Design
The traffic signal standard GSPs under Section 8-20 shall apply for foundations
in substandard soils.
D. Foundation Quantities
1. Barrier quantities are approximate and can be used for all Foundation Types:
Class 4000 Concrete
Grade 60 Rebar

7.15 CY (over shaft foundation)
372 lbs

2. Miscellaneous steel quantities (anchor rods, anchor plate, and template) for all
Monotube Sign Structure foundation types are listed below (per foundation).
Quantities vary with span lengths as shown.
60 feet and under
= 1,002 pounds
61 feet to 90 feet
= 1,401 pounds
91 feet to 120 feet
= 1,503 pounds
121 feet to 180 feet
Barrier mounted sign bridge not recommended
for these spans.
3. Monotube Sign Structure Foundation Type 1-3 quantities for concrete, rebar
and excavation are given in Table 10.1.5-1. For Sign Bridges, the quantities
shown below are for one foundation and there are two foundations per Sign
Bridge. If the depth “Z” shown in the table on Bridge Standard Drawing 10.1A4-1 is increased, these values should be recalculated.
Cantilever Signs

Sign Bridges

Concrete Cl. 4000
(cu. yard)

20′ and
Under

20′ – 30′

30' – 35'

60′ and
Under

60′ – 90′

Type 1

6.3

7.5

9.4

7.7

9.4

10.6

11.4

Type 2

8.0

10.5

12.2

10.0

12.2

14.1

15.0

Type 3

11.1

14.1

16.1

13.0

16.1

18.6

20.0

Type 1

685

1,027

2,251

1,168

2,251

3,256

4,255

Type 2

772

1,233

1,724

1,190

1,724

2,385

2,838

Type 3

917

1,509

2,136

1,421

2,136

2,946

3,572

Type 1

9.8

10.9

12.8

10.9

12.8

14.1

14.9

Type 2

20.7

25.7

29.0

24.6

29.0

32.9

34.6

Type 3

29.0

34.6

39.0

32.9

39.0

44.0

47.8

90′ – 120′ 120′ – 180′

Rebar Gr. 60 Pounds

Excavation (cu. yard)

Sign Structure Foundation Material Quantities
Table 10.1.5-1

Page 10-14

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

10.1.6

Signs, Barriers, Approach Slabs, and Utilities

Truss Sign Bridges: Foundation Sheet Design Guidelines
If a Truss sign structure is used, refer to Standard Plans for foundation details. There
are four items that should be addressed when using the Standard Plans, which are
outlined below. For details for F-shape barrier details not shown in Standard Plans
contact Bridge Office to access archived Bridge Office details.
1. Determine conduit needs. If none exist, delete all references to conduit. If conduit
is required, verify with the Region as to size and quantity.
2. Show sign bridge base elevation, number, dimension and station.
3. The concrete barrier transition section shall be in accordance with the
Standard Plans.
4. The quantities shall be based on the Standard Plans details as needed.

WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-15

Signs, Barriers, Approach Slabs, and Utilities

10.2

Bridge Traffic Barriers

10.2.1

General Guidelines

Chapter 10

The design criteria for traffic barriers on structures shall be in accordance with
Section 13 of the AASHTO LRFD. The following guidelines supplement the
requirements in AASHTO LRFD.
The WSDOT Bridge and Structures standard for traffic barriers on new bridges and
bridge approach slabs shall be a 42 inch Single Slope concrete barrier for all interstate
routes, major highway routes, and over National Highway System (NHS) routes unless
special conditions apply. The 42 inch requirement is in accordance with the “Fall
Protection” requirements of the Washington State Department of Labor and Industries,
(WAC 296-155-24609 and WAC 296-155-24615 2a), and the July 2014 AASHTO
resolution for Fall Protection.
The WSDOT Bridge and Structures standard for existing bridges, bridge rehabilitation
projects, Structural Earth Wall and Geosynthetic wall traffic barriers, retaining walls,
and median barrier shall be a 34 inch or 42 inch Single Slope traffic barrier.
Use of a 32 inch or 42 inch F Shape concrete barrier shall be limited to locations where
there is F Shape concrete barrier on the approach grade to a bridge or for continuity
within a corridor.
Use of a 32 inch Pedestrian concrete barrier shall be limited to locations with sidewalk.
Use of a 42 inch or 54 inch combination barrier (32 inch or 34 inch concrete barrier
increased by metal railing) are less economical, require more maintenance, and shall
be limited for purposes such as scenic roads. For additional requirements for pedestrian
and bicycle/pedestrian railings, see Section 10.5.1.
It shall be the Bridge and Structures Office policy to design traffic barriers for new
structures using minimum Test Level 4 (TL-4) design criteria regardless of the height
of the barrier safety shape. The Test Level shall be indicated in the Bridge General
Notes or General Notes. A Test Level 5 (TL-5) traffic barrier shall be used on new
structures under the following conditions:
• “T” intersections on a structure.
• Barriers on structures with a radius of curvature less than 500 ft, TL-4 is adequate
for the barrier on the inside of the curve.
• Greater than 10 percent Average Daily Truck Traffic (ADTT) where approach
speeds are 50 mph or greater (e.g., freeway off-ramps).
• Accident history suggests a need.
• Protection of schools, business, or other important facilities below the bridge.
See AASHTO LRFD Section 13 for additional Test Level selection criteria.
A list of crash tested barriers can be found through the FHWA website at:
https://safety.fhwa.dot.gov/roadway_dept/countermeasures/reduce_crash_severity/
listing.cfm?code=long

Page 10-16

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

10.2.2

Signs, Barriers, Approach Slabs, and Utilities

Bridge Railing Test Levels
It must be recognized that bridge traffic barrier performance needs differ greatly from
site to site. Barrier designs and costs should match facility needs. This concept is
embodied in the AASHTO LRFD. Six different bridge railing test levels, TL-1 thru TL6, and associated crash test/performance requirements are given in AASHTO LRFD
Section 13 along with guidance for determining the appropriate test level for
a given bridge.

10.2.3

Available WSDOT Designs
A. Service Level 1 (SL-1) Weak Post Guardrail (TL-2)
This bridge traffic barrier is a crash tested weak post rail system. It was developed
by Southwest Research Institute and reported in NCHRP Report 239 for lowvolume rural roadways with little accident history. This design has been utilized on
a number of short concrete spans and timber bridges. A failure mechanism is built
into this rail system such that upon a 10 kip applied impact load, the post will break
away from the mounting bracket. The thrie beam guardrail will contain the vehicle
by virtue of its ribbon strength. To ensure minimal or no damage to the bridge deck
and stringers, the breakaway connection may be modified for a lower impact load
(2 kip minimum) with approval of the Bridge Design Engineer. The 2 kip minimum
equivalent impact load is based on evaluation of the wood rail post strength tested
in NCHRP Report 239. The appropriate guardrail approach transition shall be a
Case 14 placement as shown on WSDOT Standard Plan C-2h. For complete details
see Appendix 10.4-A1.

WSDOT Bridge Design Manual M 23-50.17
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Page 10-17

Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

B. Texas T-411 Aesthetic Concrete Baluster (TL-2)





Texas developed this standard for a section of highway that was considered to
be a historic landmark. The existing deficient concrete baluster rail was replaced
with a much stronger concrete baluster that satisfactorily passed the crash test
performance criteria set forth by the NCHRP Report 230. For details, visit
TXDOT’s Bridge and Structures website at
www.txdot.gov/inside-txdot/division/bridge.html.

SL-1 Weak Post

Texas T-411

Figure 10.2.3-1


C. Traffic Barrier – 32″ Shape F (TL-4)



This configuration was crash tested in the late 1960s, along with the New Jersey
Shape, under NCHRP 230 and again at this test level under NCHRP 350. The
steeper vertical shape tested better than the New Jersey face and had less of
an inclination to roll vehicles over upon impact. For future deck overlays, an
encroachment of 2.0 in., leaving a 1.0 in. lip has been satisfactorily tested for safety
shapes, see AASHTO Article C13.7.3.2. For complete details see Bridge Standard
Drawings 10.2-A1 and 10.2-A2.

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Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

D. Traffic Barrier – 34″ Single Slope (TL-4)
This concrete traffic barrier system was designed by the state of California in the
1990s to speed up construction by using the “slip forming” method of construction.
It was tested under NCHRP 350. WSDOT has increased the height from 32″ to 34″
to match the approach traffic barrier height and to allow the placement of one HMA
overlay. Due to inherent problems with the “slip forming” method of traffic barrier
construction WSDOT has increased the concrete cover on the traffic side from 1½″
to 2½″. For complete details, see Bridge Standard Drawing 10.2-A3.







32″ F-Shape











34″ Single Slope



Figure 
10.2.3-2

E. Pedestrian Barrier (TL-4)

This crash tested rail system offers a simple to build concrete alternative to the
New Jersey and F-Shape configurations. This system was crash tested under
both NCHRP 230 and 350. Since the traffic face geometry is better for pedestrians
and bicyclists, WSDOT uses this system primarily in conjunction with a sidewalk.
For complete details, see Bridge Standard Drawing 10.2-A4.

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Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

F. Oregon 3-Tube Curb Mounted Traffic Barrier (TL-4)
This is another crash tested traffic barrier that offers a lightweight, see-through
option. This system was crash tested under both NCHRP 230 and 350. A rigid thrie
beam guardrail transition is required at the bridge ends. For details, see the Oregon
Bridge and Structure website at www.oregon.gov/ODOT/HWY/ENGSERVICES/
Pages/bridge_drawings.aspx.











32″ Vertical

Figure 10.2.3-3

Oregon 3-Tube

G. Traffic Barrier – 42″ Shape F (TL-4 and TL-5)



This barrier is very similar to the 32″ F-shape concrete barrier in that the slope of
the front surface is the same except for height. For complete details, see Bridge
Standard Drawing 10.2-A6.

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Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

H. Traffic Barrier – 42″ Single Slope (TL-4 and TL-5)
This option offers a simple to build alternative to the Shape F configuration. For
complete details see Bridge Standard Drawing 10.2-A6.


 

42″ F-Shape


10.2.4









42″ Single Slope


Figure 10.2.3-4

Design Criteria
A. Design Values
AASHTO LRFD Appendix A13 shall be used to design bridge traffic barriers and
their supporting elements (i.e. the deck).
Concrete traffic barriers shall be designed using yield line analysis as described in
AASHTO LRFD A13.3.1. The impact loads on traffic barriers shall be applied at
the height specified for intended Test Levels in accordance to the AASHTO LRFD
Table A13.2-1 “Design Forces for Traffic Railing (32-inch for TL-4, and 42inch for TL-5)”. WSDOT Standard F Shape and Single Slope barriers meet
these requirements.
Deck overhangs supporting traffic barriers shall be designed in accordance with
AASHTO LRFD A13.4. For concrete traffic barriers in Design Case 1, AASHTO
requires MS, the deck overhang flexural resistance, to be greater than Mc of
the concrete traffic barrier base. This requirement is consistent with yield line
analysis (see AASHTO LRFD CA13.3.1), but results in over conservative deck
overhang designs.

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June 2017

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Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

In order to prevent this unnecessary overdesign of the deck overhang, the nominal
traffic barrier resistance to transverse load RW (AASHTO LRFD A13.3.1)
transferred from the traffic barrier to deck overhang shall not exceed 120 percent
of the design force Ft (AASHTO LFRD Table A13.2-1) required for a traffic
barrier. The deck overhang shall be designed in accordance with the requirements
of AASHTO LRFD A13.4.2 to provide a flexural resistance Ms, acting coincident
with the tensile force T. At the inside face of the barrier Ms may be taken as:
for an interior barrier segment–Ms =

Rw · H
LC + 2 · H

and for an end barrier segment–Ms =

Rw · H
LC + H

However, Ms need not be taken greater than Mc at the base. T shall be taken as:
for an interior barrier segment–T =
and for an end barrier segment–T =

Rw
LC + 2 · H
Rw

LC + H

The end segment requirement may be waived if continuity between adjacent
barriers is provided.
When an HMA overlay is required for initial construction, increase the weight for
Shape F traffic barrier. See Section 10.2.4.C for details.
B. Geometry
The traffic face geometry is part of the crash test and shall not be modified.
Contact the WSDOT Bridge and Structure Office Bridge Rail Specialist for
further guidance.
Thickening of the traffic barrier is permissible for architectural reasons. Concrete
clear cover must meet minimum concrete cover requirements but can be increased
to accommodate rustication grooves or patterns.
C. Standard Detail Sheet Modifications
When designing and detailing a bridge traffic barrier on a superelevated bridge
deck the following guidelines shall be used:
• For bridge decks with a superelevation of 8 percent or less, the traffic
barriers (and the median barrier, if any) shall be oriented perpendicular to the
bridge deck.
• For bridge decks with a superelevation of more than 8 percent, the traffic
barrier on the low side of the bridge (and median barrier, if any) shall be
oriented perpendicular to an 8 percent superelevated bridge deck. For this
situation, the traffic barrier on the high side of the bridge shall be oriented
perpendicular to the bridge deck.

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Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

The standard detail sheets are generic and may need to be modified for each
project. The permissible modifications are:
• Removal of the electrical conduit, junction box, and deflection fitting details.
• Removal of design notes.
• If the traffic barrier does not continue on to a wall, remove W1 and W2 rebar
references.
• Removal of the non-applicable guardrail end connection details and verbiage.
• If guardrail is attached to the traffic barrier, use either the thrie beam end
section “Design F” detail or the w-beam end section “Design F” detail. If the
traffic barrier continues off the bridge, approach slab, or wall, remove the
following:
• Guardrail details from all sheets.
• Conduit end flare detail.
• Modified end section detail and R1A or R2A rebar details from all sheets.
• End section bevel.
• Increase the 3″ toe dimension of the Shape F traffic barriers up to 6″ to
accommodate HMA overlays.

WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-23

Barrier Impact Design Forces on Traffic Barrier & Deck Overhang
Single Slope 42 in .
Type F 42 in .
Type F 42 in .
Single Slope 42 in .
Single Slope 34 in .
(TL-4)
Parameters
(TL-4)
(TL-4)
(TL-5)
(TL-5)
Interior
End*
Interior
End*
Interior
End*
Interior
End*
Interior
End*
19 .33
19 .33
25 .93
25 .93
25 .93
25 .93
22 .42
36 .04
22 .42
22 .42
Average Mc (ft-kips/ft)
26 .03
26 .03
32 .87
32 .87
32 .87
32 .87
30 .66
49 .52
30 .66
30 .66
Mc at Base (ft-kips/ft)
46 .01
43 .16
72 .54
71 .72
98 .23
96 .93
83 .85
79 .12
60 .66
57 .26
Mw (ft-kips)
Traffic Barrier
9 .30
4 .81
10 .77
5 .32
15 .05
9 .39
14 .99
8 .87
Design
10 .63
5 .21
Lc (ft)
126 .92
65 .69
159 .62
78 .83
223 .00
139 .20
192 .02
182 .61
136 .17
66 .81
Rw (kips)
54 .00
54 .00
54 .00
54 .00
124 .00
124 .00
124 .00
124 .00
54 .00
54 .00
Ft (kips)
64 .80
64 .80
64 .80
64 .80
148 .80
148 .80
148 .80
148 .80
64 .80
64 .80
1 .2*Ft (kips)
64 .80
64 .80
64 .80
64 .80
148 .80
139 .20
148 .80
148 .80
64 .80
64 .80
Design Rw (kips)
Deck
12 .27
24 .01
9 .72
19 .59
23 .62
37 .79
23 .69
42 .11
9 .80
19 .83
Overhang
Rw*H/(Lc+aH) (ft-kips/ft)**
Design
12 .27
24 .01
9 .72
19 .59
23 .62
32 .87
23 .69
42 .11
9 .80
19 .83
Design Ms (ft-kips/ft)
3 .68
7 .44
Design T (kips/ft)
4 .65
8 .73
4 .33
8 .47
3 .65
7 .35
6 .75
10 .80
6 .77
12 .03
2
0 .29
0 .57
0 .29
0 .59
0 .17
0 .35
0 .43
0 .60
0 .49
0 .91
0 .20
0 .41
A
required
(in
/ft)
s
Deck to
0 .41
0 .62
0 .41
0 .62
0 .41
0 .62
0 .59
0 .89
0 .59
0 .97
0 .41
0 .62
As provided (in2/ft)
Barrier
Reinforcement
#5 @ 9 in #5 @ 6 in #5 @ 9 in #5 @ 6 in #5 @ 9 in #5 @ 6 in #5 @ 9 in #5 @ 6 in #6 @ 9 in #6 @ 6 in #6 @ 8 in #6 @ 5 .5 in
S1 Bars

Page 10-24

fv = 60 ksi
f'c = 4 ksi

Table 10.2.4-1

Loads are based on vehicle impact only . For deck overhang design, the designer must also check other limit states per LRFD A13 .4 .1 .

**a = 1 for an end segment and 2 for an interior segment

where end section reinforcement differs from interior segments) . Parameters for modified end segments shall be calculated per AASHTO-LRFD article A13 .3, A13 .4, and the WSDOT BDM .

*Traffic barrier cross sectional dimensions and reinforcement used for calculation of end segment parameters are the same as interior segments (except TL-5 Single Slope 42 in . barrier

Type F 32 in .
(TL-4)
Interior
End*
20 .55
20 .55
27 .15
27 .15
42 .47
46 .04
8 .62
4 .76
132 .82
73 .31
54 .00
54 .00
64 .80
64 .80
64 .80
64 .80
12 .39
23 .28
12 .39
23 .28

Signs, Barriers, Approach Slabs, and Utilities
Chapter 10

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

D. Miscellaneous Design Information
• Show the back of pavement seat in the “Plan – Traffic Barrier” detail.
• At roadway expansion joints, show traffic barrier joints normal to centerline
except as shown on sheets Appendix 9.1-A1-1 and 9.1-A2-1.
• When an overlay is required, the 2′-8″ minimum dimension shown in the
“Typical Section – Traffic Barrier” shall be referenced to the top of the overlay.
• When bridge lighting is part of the contract, include the lighting bracket
anchorage detail sheet.
• Approximate quantities for the traffic barrier sheets are:
Barrier Type

Concrete Weight (lb/ft)

Steel Weight (lb/ft)

32″ F-shape (3″ toe)

460

18.6

32″ F-shape (6″ toe)

510

19.1

34″ Single Slope

490

16.1

42″ F-shape (3″ toe)

710

25.8

42″ F-shape (6″ toe)

765

28.4

42″ Single Slope

670

22.9

32″ Pedestrian

640*

14.7

Using concrete class 4000 with a unit weight of 155 lb/ft3
*with 6″ sidewalk, will vary with sidewalk thickness

• Steel Reinforcement Bars:
S1 & S2 or S3 & S4 and W1 & W2 bars (if used) shall be included in the Bar List.
S1, S3, and W1 bars shall be epoxy coated.

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Signs, Barriers, Approach Slabs, and Utilities

10.3

At Grade Concrete Barriers

10.3.1

Differential Grade Concrete Barriers

Chapter 10

The top of the differential grade concrete barrier shall have a minimum width of 6″.
If a luminaire or sign is to be mounted on top of the differential grade concrete barrier,
then the width shall be increased to accommodate the mounting plate and 6″ of clear
distance on each side of the luminaire or sign pole. The transition flare rate shall follow
the Design Manual M 22-01.
A. Differential Grade Concrete Barriers
Concrete barriers at grade are sometimes required in median areas with different
roadway elevations on each side. The standard Single Slope barrier can be used for
a grade difference up to 10″ for a 2′-10″ safety shape and up to 6″ for a 3′-6″ safety
shape. See Standard Plans C-70.10 and C-80.10 for details.
If the difference in grade elevations is 4′-0″ or less, then the concrete barrier
shall be designed as a rigid system in accordance with AASHTO LRFD with the
following requirements:
1. All applicable loads shall be applied in accordance to AASHTO LRFD
Section 3. The structural capacity of the differential grade concrete barrier
and supporting elements shall be designed for the required Test Level vehicle
impact design forces in accordance with AASHTO LRFD Sections 5 and 13.
Any section along the differential grade barrier and supporting elements shall
not fail in shear, bending, or torsion when the barrier is subjected to the TL
impact forces.
2. For soil loads without vehicle impact loads, the concrete barrier shall
be designed as a retaining wall (barrier weight resists overturning and
sliding). Passive soil resistance may be considered with concurrence by the
geotechnical engineer.
3. Vehicle impact loads shall be applied on the side of the concrete barrier
retaining soil if there is traffic on both sides. The vehicle impact loads shall be
applied at the height specified for intended Test Levels in accordance to the
AASHTO LRFD Section 13, Table A13.2-1 “Design Forces for Traffic Railing
(32-inch for TL-4, and 42-inch for TL-5)”.
4. For soil loads with vehicle impact loads, the AASHTO LRFD Extreme Event
loading for vehicular collision shall also be analyzed. Equivalent Static Load
(ESL) per NCHRP Report 663 may be applied as the transverse vehicle impact
load for evaluating sliding, bearing, and overturning only. For TL-3 and TL-4
barrier systems, the ESL shall be 10 kips and for TL-5, the ESL shall be
23 kips. The point of rotation for overturning shall be taken at the toe of barrier.
Sliding resistance factor shall be 0.8 and overturning resistance factor shall be
0.5 (supersedes AASHTO 10.5.5.3.3).

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Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

5. The effective length of the concrete barrier required for stability shall be no
more than 10 times the overall height, but not to exceed the length between
barrier expansion joints (or one precast section). The barrier shall act as a rigid
body behavior and shall be continuous throughout this length of barrier. Any
coupling between adjacent barrier sections or friction that may exist between
free edges of barrier and the surrounding soil shall be neglected.
6. A special impact analysis shall be performed at the barrier ends if the barrier
terminates without being connected to a rigid object or dowelled to another
barrier. Differential barrier deflection from barrier impact may cause a vehicle
to “snag” on the undeflected barrier. The barrier depth may need to be increased
at the end to prevent this deflection.
7. The differential grade traffic barrier shall have dummy joints at 8 to 12 foot
centers based on project requirements.
8. Full depth expansion joints with shear dowels at the top will be required at
intervals based on analysis but not to exceed a 120′-0″ maximum spacing.
9. Barrier bottom shall be embedded a minimum 6″ below roadway. Roadway
subgrade and ballast shall be extended below whole width of differential grade
barrier.
Median traffic barriers with a grade difference greater than 4′-0″ shall be designed
as standard plan retaining walls with a traffic barrier at the top and a barrier shape
at the cut face.
10.3.2

Traffic Barrier Moment Slab
A. General
The guidelines provided herein are based on NCHRP Report 663 with the
exception that a resistance factor of 0.5 shall be used to determine rotational
resistance. This guideline is applicable for TL-3, TL-4, and TL-5 barrier systems as
defined in Section 13 of AASHTO LRFD Bridge Design Specifications.
Ls = 10 K Static Equivalent for
TL3 and TL4 Barriers

Ls = 23 K Static Equivalent for
TL5 Barriers

W
ha = Moment Arm

Top of Barrier to
Point of Rotations

C.G.

Pavement Overburden

Roadway Base Course
A = Point of Rotation
Compacted Backfill

P
Varies with Wall Type

Global Stability of Barrier–Moment Slab System
Figure 10.3.2-1

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Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

B. Guidelines for Moment Slab Design
1. Structural Capacity
The structural capacity of the barrier and concrete moment slab shall be
designed using impulse loads at appropriate Test Level (TL-3, TL-4, TL5) applied to the top of the barrier in accordance with Sections 5 and 13 of
AASHTO LRFD. Any section along the moment slab shall not fail in shear,
bending, or torsion when the barrier is subjected to the design impact loads.
The torsion capacity of the moment slab must be equal to or greater than the
traffic barrier moment generated by the specified TL static equivalent of the
vehicle impulse load.
The moment slab shall be designed as a deck supporting barrier in accordance
to AASHTO LRFD A13.4.2 as modified by BDM Section 10.2.4.A. The
moment slab reinforcement shall be designed to resist combined forces
from the moment MS (kip-ft/ft) and the tensile force T (kip/ft). MS and T are
determined from the lesser of the ultimate transverse resistance of barrier RW
(kip) and 120 percent of transverse vehicle impact force FT (kip). MS is not to
be exceeded by the ultimate strength of barrier at its base MC (kip-ft/ft).
2. Global Stability
Bearing stress, sliding, and overturning stability of the moment slab shall be
based on an Equivalent Static Load (ESL) applied at the height specified for
intended Test Levels in accordance to the AASHTO LRFD Section 13, Table
A13.2-1 “Design Forces for Traffic Railing (32-inch for TL-4, and 42-inch for
TL-5)”. For TL-3 and TL-4 barrier systems, the ESL shall be 10 kips. For TL-5
barrier systems, the ESL shall be 23 kips.
The Equivalent Static Load (ESL) is assumed to distribute over the length
of continuous moment slab through rigid body behavior. Barrier shall also
be continuous or have shear connections between barrier sections if precast
throughout this length of moment slab. Any coupling between adjacent moment
slabs or friction that may exist between free edges of the moment slab and the
surrounding soil should be neglected.
3. Minimum and Maximum Dimensions
Moment slabs shall have a minimum width of 4.0 feet measured from the point
of rotation to the heel of the slab and a minimum average depth of 0.83 feet.
Moment slabs meeting these minimum requirements are assumed to provide
rigid body behavior up to a length of 60 feet limited to the length between
moment slab joints.
Rigid body behavior may be increased from 60 feet to a maximum of 120 feet
if the torsional rigidity constant of the moment slab is proportionately increased
and the reinforcing steel is designed to resist combined shear, moment, and
torsion from TL static equivalent of the vehicle impulse loads.
For example: Rigid Body Length = (J’/J60)x(60 ft.) < 120 feet

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Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

The torsional rigidity constant for moment slabs shall be based on a solid
rectangle using the following formula:

Where:
2a = total width of moment slab
2b = average depth of moment slab
For example:
Minimum Moment Slab Width = 48 inches: a = 24 inches
Minimum Moment Slab Average Depth = 10 inches: b = 5 inches
J = J60 = 13,900 in4

4. Sliding of the Barrier
The factored static resistance to sliding (φP) of the barrier-moment slab system
along its base shall satisfy the following condition (Figure 2).
φP ≥ γLs
Where:
Ls =
φ =

γ =

P =

Equivalent Static Load (10 kips for TL-3 or TL-4, 23 kips for TL-5)
resistance factor (0.8) Supersedes AASHTO 10.5.5.3.3—
Other Extreme Limit States
load factor (1.0) for TL-3 and TL-4 [crash tested extreme event]
load factor (1.2) for TL-5 [untested extreme event]
static resistance (kips)

P shall be calculated as:
Where:
W =

φr =

(1)

(2)

P = W tan φr

weight of the monolithic section of barrier and moment slab between
joints or assumed length of rigid body behavior whichever is less,
plus any material laying on top of the moment slab
friction angle of the soil on the moment slab interface (°)

If the soil-moment slab interface is rough (e.g., cast in place), φr is equal to the
friction angle of the soil φs. If the soil-moment slab interface is smooth (e.g.,
precast), tan φr shall be reduced accordingly (0.8 tan φs).

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Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

5. Overturning of the Barrier
The factored static moment resistance (φM) of the barrier-moment slab system
to over-turning shall satisfy the following condition (Figure 1).
The factored static moment resistance (φM) of the barrier-moment slab system
to overturning shall satisfy the following condition (Figure 1).
φM ≥ γLs ha

(3)

Where:
A = point of rotation, where the toe of the moment slab makes contact

with compacted backfill adjacent to the fascia wall
Lw = width of moment slab
Ls = Equivalent Static Load (10 kips for TL-3 and TL-4) (23 kips for TL-5)
φ = resistance factor (0.5) Supersedes AASHTO 10.5.5.3.3—

Other Extreme Limit States and NCHRP Report 663
γ = load factor (1.0) for TL-3 and TL-4 [crash tested extreme event]

load factor (1.2) for TL-5 [untested extreme event]
ha = moment arm taken as the vertical distance from the point of impact

due to the dynamic force (top of the barrier) to the point of rotation A
M = static moment resistance (kips-ft)

M shall be calculated as:
M = W (La) (4)
W = weight of the monolithic section of barrier and moment slab between

joints or assumed length of rigid body behavior whichever is less,

plus any material laying on top of the moment slab
La = horizontal distance from the center of gravity of the weight W

to point of rotation A

The moment contribution due to any coupling between adjacent moment slabs,
shear strength of the overburden soil, or friction which may exist between the
backside of the moment slab and the surrounding soil shall be neglected.
C. Guidelines for the Soil Reinforcement
Design of the soil reinforcement shall be in accordance with the Geotechnical
Design Manual Chapter 15.
D. Design of the Wall Panel
The wall panels shall be designed to resist the dynamic pressure distributions as
defined in the Geotechnical Design Manual Chapter 15.
The wall panel shall have sufficient structural capacity to resist the maximum
design rupture load for the wall reinforcement designed in accordance with the
Geotechnical Design Manual Chapter 15.
The static load is not included because it is not located at the panel connection.

Page 10-30

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

10.3.3

Signs, Barriers, Approach Slabs, and Utilities

Precast Concrete Barrier
A. Concrete Barrier Type 2
“Concrete Barrier Type 2” (see Standard Plan C-8) may be used on bridges
for median applications or for temporary traffic control based on the
following guidelines:
1. For temporary applications, no anchorage is required if there is 2 feet or
greater slide distance between the back of the traffic barrier and an object and
3 feet or greater to the edge of the bridge deck or a severe drop off (see Design
Manual M 22-01).
2. For permanent applications in the median, no anchorage will be required if
there is a 3 foot or greater slide distance between the traffic barrier and the
traffic lane.
3. For temporary applications, the traffic barrier shall not be placed closer than
9 inches to the edge of a bridge deck or substantial drop-off and shall be
anchored (see Standard Plans K-80.35 and K-80.37).
4. The traffic barrier shall not be used to retain soil that is sloped or greater than
the barrier height or soil that supports a traffic surcharge.
B. Concrete Barrier Type 4 and Alternative Temporary Concrete Barrier
“Concrete Barrier Type 4 (see the Standard Plan C-8a), is not a free standing
traffic barrier. This barrier shall be placed against a rigid vertical surface that is
at least as tall as the traffic barrier. In addition, Alternative Temporary Concrete
Barrier Type 4 – Narrow Base (Standard Plan K-80.30) shall be anchored to the
bridge deck as shown in Standard Plan K-80.37. The “Concrete Barrier Type 4 and
Alternative Temporary Concrete Barrier” are not designed for soil retention.

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June 2017

Page 10-31

Signs, Barriers, Approach Slabs, and Utilities

10.4

Bridge Traffic Barrier Rehabilitation

10.4.1

Policy

Chapter 10

The bridge traffic barrier retrofit policy is: “to systematically improve or replace
existing deficient rails within the limits of roadway resurfacing projects.” This is
accomplished by:
• Utilizing an approved crash tested rail system that is appropriate for the site or
• Designing a traffic barrier system to the strength requirements set forth by
Section 2 of AASHTO Standard Specifications for Highway Bridges, 17th edition.
10.4.2

Guidelines
A strength and geometric review is required for all bridge rail rehabilitation projects. If
the strength of the existing bridge rail is unable to resist a 10 kip barrier impact design
load or has not been crash tested, then modifications or replacement will be required to
improve its redirectional characteristics and strength. Bridges that have deficient bridge
traffic barriers were designed to older codes.
The AASHTO LFD load of 10 kips shall be used in the retrofit of existing bridge traffic
barrier systems constructed prior to the year 2000.
The use of the AASHTO LRFD criteria to design bridge traffic barrier rehabs will
result in a bridge deck that has insufficient reinforcement to resist moment from
a traffic barrier impact load and will increase the retrofit cost due to expensive
deck modifications.
If the design of the bridge rehabilitation includes other bridge components that will
be designed using AASHTO LRFD then the following minimum equivalent Extreme
Event (CT) traffic barrier loading can be used:
Flexure = (1.3)*(1.67)*(10 kip) / (0.9) = 24.10 kip
Shear = (1.3)*(1.67)*(10 kip) / (0.85) = 25.54 kip

10.4.3

Design Criteria
Standard thrie beam guardrail post spacing is 6′-3″ except for the SL-1 Weak Post,
which is at 8′-4″. Post spacing can be increased up to 10′-0″ if the thrie beam guardrail
is nested (doubled up).
Gaps in the guardrail are not allowed because they produce snagging hazards. The
exceptions to this are:
• Movable bridges at the expansion joints of the movable sections.
• At traffic gates and drop down net barriers.
• At stairways.
Design F guardrail end sections will be used at the approach and trailing end of
these gaps.
For Bridge Traffic Barrier Rehabilitation the following information will be needed
from the Region Design office:
• Bridge Site Data Rehabilitation Sheet – DOT Form 235-002A.
• Photos, preferably digital JPEG format.

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Signs, Barriers, Approach Slabs, and Utilities

• Layout with existing dimensions.
• Standard Plan thrie beam guardrail transitions (selected by Region Design office)
to be used at each corner of the bridge (contact bridges and structures office for
thrie beam height).
• Location of any existing utilities.
• Measurements of existing ACP to top of curb at the four corners, midpoints
and the locations of minimum and maximum difference (five locations each side
as a minimum).
• Diagram of the location of Type 3 anchors, if present, including a plan view with
vertical and horizontal dimensions of the location of the Type 3 anchor connection
relative to the intersecting point of the back of pavement seat with the curb line.
• The proposed overlay type, quantities of removal and placement.
• For timber bridges, the field measurement of the distance from the edge of bridge
deck to the first and second stringer is required for mounting plate design.
Placement of the retrofit system will be determined from the Design Manual
M 22-01. Exceptions to this are bridges with sidewalk strength problems,
pedestrian access issues, or vehicle snagging problems.
10.4.4

WSDOT Bridge Inventory of Bridge Rails
The WSDOT Bridge Preservation Office maintains an inventory of all bridges in the
state on the State of Washington Inventory of Bridges.
Concrete balusters are deficient for current lateral load capacity requirements.
They have approximately 3 kips of capacity whereas 10 kips is required.
The combination high-base concrete parapet and metal rail may or may not be
considered adequate depending upon the rail type. The metal rail Type R, S, and SB
attached to the top of the high-base parapet are considered capable of resisting the
required 5 kips of lateral load. Types 3, 1B, and 3A are considered inadequate. See the
Design Manual M 22-01 for replacement criteria.

10.4.5

Available Retrofit Designs
A. Washington Thrie Beam Retrofit of Concrete Balusters
This system consists of thrie beam guardrail stiffening of existing concrete
baluster rails with timber blockouts. The Southwest Research Institute conducted
full-scale crash tests of this retrofit in 1987. Results of the tests were satisfactory
and complied with criteria for a Test Level 2 (TL-2) category in the Guide
Specifications. For complete details see Bridge Standard Drawing 10.4-A1-1.
B. New York Thrie Beam Guardrail
This crash tested rail system can be utilized at the top of a raised concrete sidewalk
to separate pedestrian traffic from the vehicular traffic or can be mounted directly to
the top of the concrete deck. For complete details see Thrie Beam Retrofit Concrete
Curb in Appendix 10.4-A1-3.
C. Concrete Parapet Retrofit
This is similar to the New York system. For complete details see
Appendix 10.4-A1-2.

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Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

D. SL-1 Weak Post
This design has been utilized on some short concrete spans and timber bridges.
A failure mechanism is built into this rail system so that upon impact with a 10 kip
load the post will break away from the mounting bracket. The thrie beam guardrail
will contain the vehicle by virtue of its ribbon strength. To ensure minimal damage
to the bridge deck and stringers, the breakaway connection may be modified for a
lower impact load (2 kip minimum) with approval of the Bridge Design Engineer.
For complete details, see Bridge Standard Drawing 10.4-A1-4.
10.4.6

Available Replacement Designs
A. Traffic Barrier – Shape F Retrofit
This is WSDOT’s preferred replacement of deficient traffic barriers and parapets on
high volume highways with a large truck percentage. All interstate highway bridges
shall use this type of barrier unless special conditions apply. For complete details
see Bridge Standard Drawing 10.4-A2.

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10.5

Bridge Railing

10.5.1

Design
WSDOT pedestrian and bicycle/pedestrian railings are designed in accordance with
Chapter 13 in the AASHTO LRFD. The AASHTO LRFD calls for a minimum of 42″
for bicycle railings whereas WSDOT requires a minimum height of 54″ on structures.
The railings in Section 10.5.2 are not designed for vehicular impact loads assuming
location is low speed, location is outside of Design Clear Zone as defined in the Design
Manual Chapter 1600, or location has minimal safety consequence from collapse
of railing. Railings for other locations shall be designed for vehicular impact loads
in accordance with Chapter 13 and/or 15 in the AASHTO LRFD. Emergency and
maintenance access shall be considered.
Pedestrian and bicycle railings shall be designed using a Live Load factor of 1.75.
Fall Protection railing shall meet the requirements of WAC 296-155-24609.

10.5.2

Railing Types
A. Bridge Railing Type Pedestrian
This pedestrian railing is designed to sit on top of the 32″ and 34″ traffic barriers
and to meet pedestrian height requirements of 42″. For complete details see Bridge
Standard Drawing 10.5-A1.
B. Bridge Railing Type BP and S-BP
These railings are designed to meet WSDOT’s minimum bicycle height
requirements of 54″, and sit on top of the 32″ and 34″ traffic barriers.
There are two versions—the BP and S-BP. The BP is the standard railing and is
made out of aluminum. The S-BP is the steel version designed for use in rural
areas because of aluminum theft. For complete details see Bridge Standard
Drawing 10.5-A2 and 10.5-A3.
C. Pedestrian Railing
This railing is designed to sit on top of a six-inch curb on the exterior of a bridge
sidewalk. It meets the bicycle height requirements of 54″. For complete details see
Appendix 10.5-A4.
D. Bridge Railing Type Chain Link Snow Fence and Bridge Railing Type
Snow Fence
This railing is designed to prevent large chunks of plowed snow from falling
off the bridge on to traffic below. For complete details see Appendix 10.5-A5-1
through 10.5-A5-3.
E. Bridge Railing Type Chain Link Fence
This railing is designed to minimize the amount of objects falling off the bridge on
to traffic below. For complete details see Appendix 10.5-A5-4.

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Signs, Barriers, Approach Slabs, and Utilities

10.6

Chapter 10

Bridge Approach Slabs
Bridge approaches typically experience two types of settlement, global and local.
Global settlement is consolidation of the deeper natural foundation soils. Local
settlement is mainly compression of fill materials directly beneath the approach
pavement due to construction. The combination of global and local settlements
adjacent to the bridge end piers form the characteristic “bump” in the pavement at
the bridge. The approach slab significantly reduces local settlement and will provide
a transition to the long term roadway differential settlements. Generally, abutments
with a deep foundation will have greater differential roadway settlements than spread
footing foundations.
When Are Bridge Approach Slabs Required – Bridge approach slabs are required
for all new and widened bridges, except when concurrence is reached between the
Geotechnical Branch, the Region Design Project Engineer Office, and the Bridge
and Structures Office, that approach slabs are not appropriate for a particular site. In
accordance with Design Manual M 22-01, the State Geotechnical Engineer will include
a recommendation in the geotechnical report for a bridge on whether or not bridge
approach slabs should be used at the bridge site. Factors considered while evaluating
the need for bridge approach slabs include the amount of expected settlement and the
type of bridge structure.
Standard Plan A-40.50 – The Standard Plan A-40.50 is available for the Local
Agencies (or others) to use or reference in a contract. Bridge and Structures Office
designs will provide detailed information in a customized approach slab Plan View and
show the approach slab length on the Bridge Layout Sheet.
Bridge Runoff – Bridge runoff at the abutments shall be carried off and collected at
least 10 feet beyond the bridge approach slab. Drainage structures such as grate inlets
and catch basins shall be located in accordance with Standard Plan B-95.40 and the
recommendations of the Hydraulics Branch.
Approach Pay Item –All costs in connection with constructing bridge approach slabs
are included in the unit contract price per square yard for “Bridge Approach Slab.”
The pay item includes steel reinforcing bars, approach slab anchors, concrete, and
compression seals.

10.6.1

Notes to Region for Preliminary Plan
All bridge preliminary plans shall show approach slabs at the ends of the bridges.
In the Notes to Region in the first submittal of the Preliminary Plan to the Region,
the designer shall ask the following questions:
1. Bridge approach slabs are shown for this bridge, and will be included in the Bridge
PS&E. Do you concur?
2. The approach ends of the bridge approach slabs are shown normal to the survey
line (a) with or (b) without steps (the designer shall propose one alternative).
Do you concur?
3. Please indicate the pavement type for the approach roadway.

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Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

Depending on the type and number of other roadway features present at the bridge
site (such as approach curbs and barriers, drainage structures, sidewalks, utilities
and conduit pipes) or special construction requirements such as staged construction,
other questions in the Notes to Region pertaining to the bridge approach slabs may
be appropriate.
Special staging conditions exist when the abutment skew is greater than 30° and for
wide roadway widths. This includes bridge widenings with (or without) existing
bridge approach slabs. The preliminary plan should include details showing how these
conditions are being addressed for the bridge approach slabs, and the designer shall
include appropriate questions in the Notes to Region asking for concurrence with the
proposed design.
10.6.2

Bridge Approach Slab Design Criteria
The standard bridge approach slab design is based on the following criteria:
1. The bridge approach slab is designed as a slab in accordance with
AASHTO LRFD. (Strength Limit State, IM = 1.33, no skew).
2. The support at the roadway end is assumed to be a uniform soil reaction with
a bearing length that is approximately ⅓ the length of the approach slab, or
25′/3 = 8′.
3. The Effective Span Length (Seff), regardless of approach length, is assumed to be:
25′ approach – 8′ = 17′
4. Longitudinal reinforcing bars do not require modification for skewed approaches
up to 30 degrees or for slab lengths greater than 25′.
5. The approach slab is designed with a 2″ concrete cover to the bottom reinforcing.

10.6.3

Bridge Approach Slab Detailing
The bridge approach slab and length along center line of project shall be shown in the
Plan View of the Bridge Layout sheet. The Bridge Plans will also include approach
slab information as shown in Bridge Standard Drawings 10.6-A1-1, 10.6-A1-2, and
10.6-A1-3. The Approach Slab Plan sheets should be modified as appropriate to match
the bridge site conditions. Approach slab Plan Views shall be customized for the
specific project and all irrelevant details shall be removed.
Plan View dimensions shall define the plan area of the approach slab. The minimum
dimension from the bridge is 25′. If there are skewed ends, then dimensions shall
be provided for each side of the slab, or a skew angle and one side, in addition to
the width. For slabs on a curve, the length along the project line and the width shall
be shown.
Similar to Bridge Traffic Barrier detailing, approach slab steel detailing shall show
size, spacing, and edge clearance. The number and total spaces can be determined by
the contractor. If applicable, the traffic barrier AS1 and AS2 along with the extra top
transverse bar in the slab shall be shown in the Plan View. AS1 bars shall be epoxy
coated. Also remember that the spacing of the AS1 bars decreases near joints. When
the skew is greater than 20 degrees, then AP8 bars shall be rotated at the acute corners
of the bridge approach slab.

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Chapter 10

Bending diagrams shall be shown for all custom reinforcement. All Bridge Approach
Slab sheets will have the AP2 and AP7 bars. If there is a traffic barrier, then AP8, AS1,
and AS2 bars shall be shown.
Additional layout and details may be required to address special roadway features and
construction requirements such as: roadway curbs and barriers, sidewalks, utilities and
conduits and staging.
This means, if
sidewalks and interior barriers (such as traffic
pedestrian barriers) are present, special details
will be required in the Bridge Plans to

show how the sidewalks and interior barriers 
are connected
to and constructed upon
the bridge approach slab. If the bridge construction is staged, then
the approach slabs
will also require staged construction.
10.6.4

Skewed Bridge Approach
Slabs


For all skewed abutments, the roadway end
of
the bridge approach slab shall be
normal to the roadway centerline. The Bridge Design Engineer shall
be consulted


when approach slab skew is greater than 30 degrees. Skews greater
than 20 degrees
require analysis to verify the bottom mat reinforcement, and may require expansion
joint modifications.








The roadway end of the approach may be stepped to reduce the size or to accommodate
staging construction widths. A general rule of thumb is that if the approach slab area
can be reduced by 50 SY or more, then the slab shall be stepped. At no point shall the
roadway end of the approach slab be closer than 25′ to the bridge. These criteria apply
to both new and
existing bridge approach slabs. If stepped, the design shall provide
the absolute minimum number of steps and the longitudinal construction joint shall be

located on a lane line.
See Figure 10.6.4-1
for clarification.














 
 












 
 















































Skewed Approach ~ Typical
Skewed Approach ~ Stepped












Skewed Approach



Page 10-38














Figure 10.6.4-1

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

In addition, for bridges with traffic barriers and skews greater than 20 degrees, the
AP8 bars shall be rotated in the acute corners of the bridge approach slabs. Typical
placement is shown in the flared corner steel detail, Figure 10.6.4-2.
 



Flared Corner Steel

Figure 10.6.4-2

10.6.5

Approach Anchors and Expansion Joints
For semi-integral abutments or stub abutments, the joint design shall be checked to
ensure the available movement of the standard joint is not exceeded. In general, the
approach slab is assumed to be stationary and the joint gap is designed to vary with the
bridge movement. Approach Slab Sheets 10-A1-3 and Standard Plan A-40.50 detail a
typical 2½″ compression seal. For approach slabs with barrier, the compression seal
shall extend into the barrier.
Approach slab anchors installed at bridge abutments shall be as shown in the Bridge
Plans. For bridges with semi-integral type abutments, this can be accomplished by
showing the approach slab anchors in the End Diaphragm or Pavement Seat details.
L Type Abutments – L type abutments do not require expansion joints or approach
anchors because the abutment and
bridge approach slab are both considered stationary.
A pinned connection is preferred. The L type abutment anchor detail, as shown sign
in Figure 10.6.5-1, shall be added to the abutment plan sheets. The pinned anchor for
bridges with L type abutments shall be a #5 bar at one foot spacing, bent as shown,
with 1′-0″ embedment into both the pier and the bridge approach slab. This bar shall be
included in the bar list for the bridge substructure.

WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-39

Signs, Barriers, Approach Slabs, and Utilities

Chapter 10














 




L Type Abutment
Anchor Detail
Figure 10.6.5-1

10.6.6

Bridge Approach Slab Addition or Retrofit to Existing Bridges
When bridge approach slabs are to be added or replaced on existing bridges,
modification may be required to the pavement seats. Either the new bridge approach
slab will be pinned to the existing pavement seat, or attached with approach anchors
with a widened pavement seat. Pinning is a beneficial option when applicable
as it reduces the construction cost and time.
The pinning option is only allowed on semi-integral abutments as a bridge approach
slab addition or retrofit to an existing bridge. Figure 10.6.6-1 shows the pinning detail.
As this detail eliminates the expansion joint between the bridge approach slab and
the bridge, the maximum bridge superstructure length is limited to 150′. The Bridge
Design Engineer may modify this requirement on a case by case basis. Additionally,
if the roadway end of the bridge approach slab is adjacent to PCCP roadway, then the
detail shown in Figure 10.6.6-2 applies. PCCP does not allow for as much movement
as HMA and a joint is required to reduce the possibility of buckling.
When pinning is not applicable, then the bridge approach slab shall be attached to the
bridge with approach anchors. If the existing pavement seat is less than 10 inches,
the seat shall be modified to provide an acceptable, wider pavement seat. The Bridge
Design Engineer may modify this requirement on a site-specific basis. Generic
pavement seat repair details are shown in Appendix 10.6-A2-1 for a concrete repair
and Appendix 10.6-A2-2 for a steel T-section repair. These sheets can be customized
for the project and added to the Bridge Plans.



When a bridge approach slab is added to an existing bridge, the final grade of the
bridge approach slab concrete shall match the existing grade of the concrete bridge
deck, including bridges with asphalt pavement. The existing depth of asphalt on the
bridge shall be shown in the Plans and an equal depth of asphalt placed on a new
bridge approach slab. If the existing depth of asphalt is increased or decreased, the final
grade shall also be shown on the Plans.

Page 10-40

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

Signs, Barriers, Approach Slabs, and Utilities














Pinned Approach Slab Detail


Figure 10.6.6-1







































PCCP
Roadway Dowel Bar Detail

Figure 10.6.6-2



WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-41

Signs, Barriers, Approach Slabs, and Utilities

10.6.7

Chapter 10

Bridge Approach Slab Staging
Staging plans will most likely be required when adding or retrofitting approach slabs
on existing bridges. The staging plans shall be a part of the bridge plans and shall be
on their own sheet. Coordination with the Region is required to ensure agreement
between the bridge staging sheet and the Region traffic control sheet. The longitudinal
construction joints required
for staging shall be
located on lane lines. As there may not


be enough room to allow for a lap splice in the bottom transverse bars, a mechanical
splice option shall be added. If a lap splice is
not feasible, then only the mechanical
 
splice option shall be given. See Figure 10.6.6-3.







 
 

 









Alternate Longitudinal Joint Detail

Figure 10.6.6-3





Page 10-42

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

10.7

Signs, Barriers, Approach Slabs, and Utilities

Traffic Barrier on Bridge Approach Slabs
Placing the traffic barrier on the bridge approach slab is beneficial for the
following reasons.
• The bridge approach slab resists traffic impact loads and may reduce wing wall
thickness
• Simplified construction and conduit placement
• Bridge runoff is diverted away from the abutment
Most bridges will have some long-term differential settlement between the approach
roadway and the abutment. Therefore, a gap between the bridge approach slab and
wing (or wall) shall be shown in the details. The minimum gap is twice the long-term
settlement, or 2 inches as shown in Figure 10.7-1. A 3 inch gap is also acceptable.
When the traffic barrier is placed on the bridge approach slab, the following barrier
guidelines apply.
• Barrier shall extend to the end of the bridge approach slab
• Conduit deflection or expansion fittings shall be called out at the joints
• Junction box locations shall start and end in the approach
• The top transverse reinforcing in the slab shall be sufficient to resist a traffic barrier
impact load. A 6′-0″ (hooked) #6 epoxy coated bar shall be added to the approach
slab as shown in Figure 10.7-1.


 



 

 
 
 









 






 

 






Figure 10.7-1

10.7.1

Bridge Approach Slab over Wing Walls, Cantilever Walls or
Geosynthetic Walls
All walls that are cast-in-place below the bridge approach slab should continue the
barrier soffit line to grade. This includes geosynthetic walls that have a cast-in-place
fascia. Figure 10.7.1-1 shows a generic layout at an abutment. Note the sectional Gap
Detail, Figure 10.7-1 applies.

WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-43

Page 10-44

























Signs, Barriers, Approach Slabs, and Utilities
Chapter 10

Figure 10.7.1-1

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

10.7.2

Signs, Barriers, Approach Slabs, and Utilities

Bridge Approach Slab over SE Walls
The tops of structure earth (SE) walls are uneven and shall be covered with a fascia
to provide a smooth soffit line. Usually SE walls extend well beyond the end of the
approach slab and require a moment slab. Since SEW barrier is typically 5′-0″ deep
from the top of the barrier, the soffit of the SEW barrier and bridge barrier do not
match. The transition point for the soffit line shall be at the bridge expansion joint as
shown in Figure 10.7.2-2. This requires an extended back side of the barrier at the
approach slab to cover the uneven top of the SE wall.
Battered wall systems, such as block walls, use a thickened section of the curtain wall
to hide some of the batter. The State Bridge and Structures Architect will provide
dimensions for this transition when required.




























































Figure 10.7.2-1





























Figure 10.7.2-2

WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-45

Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

10.8

Utilities Installed with New Construction

10.8.1

General Concepts
The utilities included under this section are those described in Standard Specifications
Section 6-01.10. The Bridge designer shall determine if the utility may be attached to
the structure and the location. Bridge plans shall include all hardware specifications
and details for the utility attachment as provided in any written correspondence
with the utility and the utility agreement coordinated by the WSDOT Region Utility
Engineer with the associated utility.
Responsibilities of the Utility Company – The Region or utility company will
initiate utility installations and provide design information. The utility company shall
be responsible for calculating design stresses in the utility and design of the support
system. Utility support design calculations with a State of Washington Professional
Engineer stamp, signed and dated, shall be submitted to the Bridge and Structures
Office for review. The following information shall be provided by the utility company
and shown in the final Bridge Plans.
• Location of the utility outside the limits of the bridge structure
• Number of utilities, type, size, and weight (or Class) of utility lines
• Utility minimum bending radius for the conduit or pipeline specified
Utility General Notes and Design Criteria are stated in Form 224-047. See
Figure 10.8.1-1. This form outlines most of the general information required by the
utility company to design their attachments. The Bridge Office will generally provide
the design for lightweight hanger systems, such as electrical conduits, attached to
new structures.
Confined Spaces – A confined space is any place having a limited means of exit
that is subject to the accumulation of toxic or flammable contaminants or an oxygen
deficient environment. Confined spaces include but are not limited to pontoons, box
girder bridges, storage tanks, ventilation or exhaust ducts, utility vaults, tunnels,
pipelines, and open-topped spaces more than 4 feet in depth such as pits, tubes, vaults,
and vessels.
Coating and Corrosion Protection – When the bridge is to receive pigmented sealer,
consideration shall be given to painting any exposed utility lines and hangers to match
the bridge. When a pigmented sealer is not required, steel utility conduits and hangers
shall be painted or galvanized for corrosion protection. The special provisions shall
specify cleaning and painting procedures.

Page 10-46

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

General Notes and Design Criteria for
Utility Installations to Existing Bridges
General Notes
All materials and workmanship shall be in accordance with the requirements of the state of
Washington, Department of Transportation, Standard Specifications for Road, Bridge, and
Municipal Construction, current edition. The utility conduits shall be labeled in accordance with
Section 6-01.10.
All steel in utility supports, including fastenings and anchorages, shall be galvanized in accordance
with AASHTO M-111 or M-232 (ASTM A-123 or A-153 respectively).
All utilities and utility support surfaces, including any galvanized utilities, shall be given a primer
coat of state standard formula A-6-86 and two coats of state standard formula C-9-86. The final
coat shall match the bridge color.
Galvanized metal or aluminum utilities completely hidden from public view may be exempted from
the above painting requirements.
Any painted surfaces damaged during construction shall be cleaned and painted as noted above.
Any paint splatters shall be removed from the bridge.
Appearance of the utility installation shall be given serious consideration in all cases. Where
possible, the utility installation shall be hidden from public view.
The notes and criteria explained here are presented as a guide only. Each proposed utility
installation shall be submitted to the Department of Transportation for approval on an
individual basis. Compliance with these criteria does not assure approval, nor does
variance from these criteria, for reasonable cause, necessarily exclude approval.

Design Criteria
1.

Pipelines carrying volatile fluids through a bridge superstructure shall be designed by the
utility company in accordance with WAC 480-93, Gas Companies - Safety, and Minimum
Federal Safety Standard, Title 49 Code of Federal Regulations (CFR) Section part 192. WAC
468-34-210, Pipelines - Encasement, describes when casing is required for carrying volatile
fluids across structures. Generally, casing is not required for pipelines conveying natural gas
per the requirements of WAC 468-34-210. If casing is required, then WAC 468-34-210 and
WAC 480-93-115 shall be followed.

Utilities shall not be attached above the bridge deck nor attached to railing or rail posts.

Utilities shall not extend below bottom of superstructure.

Exhibit "

Permit/Franchise
DOT Form 224-047 EF
Revised 5/10

Page

The utilities shall be provided with suitable expansion devices near bridge expansion joints
and/or other locations as required to prevent temperature and other longitudinal forces from
being transferred
to bridge
members
.
General
Notes and
Design
Criteria
for Utility Installations to Existing
5.

Form 224-047
Rigid conduit shall extend 10 feetWSDOT
(3 meters) minimum,
beyond the end of the bridge
abutment.
Figure 10.8.1-1

Utility supports shall be designed such that neither the conduit, the supports, nor the bridge
members are overstressed by any loads imposed by the utility installation.

Bridges

WSDOT Bridge Design Manual M 23-50.17
June 2017 7. Utility locations and supports shall be designed so that a failure (rupture, etc.) will not result in
damage to the bridge, the surrounding area, or be a hazard to traffic.

Page 10-47

Signs, Barriers, Approach Slabs, and Utilities

Exhibit

Chapter 10

Permit/Franchise
DOT Form 224-047 EF

Page

Revised 5/10

Rigid conduit shall extend 10 feet (3 meters) minimum, beyond the end of the bridge
abutment.

Utility supports shall be designed such that neither the conduit, the supports, nor the bridge
members are overstressed by any loads imposed by the utility installation.

Utility locations and supports shall be designed so that a failure (rupture, etc.) will not result in
damage to the bridge, the surrounding area, or be a hazard to traffic.

Conduit shall be rigid.

(Items 1 through 8 may be cross-referenced with Bridge Design Manual, Utilities Section.)
9.

Lag screws may be used for attaching brackets to wooden structures. All bolt holes shall meet
the requirements of Sections 6-04.3(4) and 6-04.3(5) of the Washington State Department of
Transportation Standard Specifications for Road, Bridge, and Municipal Construction, current
edition.

10. Welding across main members will not be permitted. All welding must be approved.
11. Utilities shall be located to minimize bridge maintenance and bridge inspection problems.
12. Attach conduits or brackets to the concrete superstructure with resin bond anchors. Lag
screws shall not be used for attachment to concrete.
13. Drilling through reinforcing steel will not be permitted. If steel is hit when drilling, the
anchorage location must be moved and the abandoned hole filled with nonshrink grout
conforming to the requirements of Section 9-20.3(2) and placement shall be as required in
Section 6-02.3(20) of the Washington State Department of Transportation Standard
Specifications for Road, Bridge, and Municipal Construction, current edition.
14. There shall be a minimum of 3 inches (80 millimeters) edge distance to the center line of bolt
holes in concrete.
15. All utilities and utility supports shall be designed not only to support their dead load but to
resist other forces from the utility (surge, etc.) and wind and earthquake forces. The utility
company may be asked to submit one set of calculations to verify their design forces.
16. Drilling into prestressed concrete members for utility attachments shall not be allowed.
17. Water or sewer lines to be placed lower than adjacent bridge footings shall be encased if
failure can cause undermining of the footing.

Exhibit "

Permit/Franchise
DOT Form 224-047 EF

Page

Revised 5/10

General Notes and Design Criteria for Utility Installations to Existing Bridges (continued)
WSDOT Form 224-047
Figure 10.8.1-1

Page 10-48

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

10.8.2

Signs, Barriers, Approach Slabs, and Utilities

Utility Design Criteria
All utilities shall be designed to resist Strength and Extreme Event Limits States. This
includes and is not limited to dead load, expansion, surge, and earthquake forces.
Designers shall review WSDOT Form 224-047 “General Notes and Design Criteria
for Utility Installations to Existing Bridges” and the items in this section when
designing a utility system or providing a review for an existing bridge attachment.
See Figure 10.8.1-1.
The Bridge Engineer shall review the utility design to ensure the utility support
system will carry all transverse and vertical loading. Loading will include (and is not
limited to): dead load, temperature expansion, dynamic action (water hammer), and
seismic inertial load. Positive resistance to loads shall be provided in all directions
perpendicular to and along the length of the utility as required by the utility engineer.
Where possible, dynamic fluid action loads shall be resisted off of the bridge. If
these loads must be resisted on the bridge, the utility engineer shall be involved
in the design of these supports. The utility engineer shall determine these design
forces being applied to the bridge. Realize these forces can be generated in any pipe
supporting moving fluids, which may include, but are not limited to: water, sewer, and
storm water.
Where utilities are insulated, the insulation system shall be designed to allow the
intended motion range of the hardware supporting the utility. This will prevent
unanticipated stresses from being added to the hanger in the event the insulation binds
up the hardware.
Utility Location – Utilities shall be located, such that a support failure will not result
in damage to the bridge, the surrounding area, or be a hazard to traffic. In most cases,
the utility shall be installed between girders. Utilities and supports shall not extend
below the bottom of the superstructure. Utilities shall be installed no lower than 1 foot
0 inches above the bottom of the girders. In some cases when appurtenances are
required (such as air release valves), care shall be taken to provide adequate space. The
utility installation shall be located so as to minimize the effect on the appearance of
the structure. Utilities shall not be attached above the bridge deck nor attached to the
railings or posts.
Termination at the Bridge Ends – Utility conduit and encasements shall extend
10 feet minimum beyond the ends of the structure in order to reduce effects of
embankment settlement on the utility and provide protection in case of future work
involving excavation near the structure. This requirement shall be shown on the plans.
Utilities off the bridge must be installed prior to paving of approaches. This should be
stated in the Special Provisions.
Utility Expansion – The utilities shall be designed with a suitable expansion system
as required to prevent longitudinal forces from being transferred to bridge members.
Water mains generally remain a constant temperature and are anchored in the ground
at the abutments. However, the bridge will move with temperature changes and seismic
forces. Pipe support systems shall be designed to allow for the bridge movements. For
short bridges, this generally means the bridge will move and the utility will not since
it is anchored at the abutments. For long bridges that require pipe expansion joints,
design shall carefully locate pipe expansion joints and the corresponding longitudinal
load-carrying support.

WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-49

Signs, Barriers, Approach Slabs, and Utilities

Chapter 10

Electrical conduits that use PVC shall have an expansion device for every 100 foot of
pipe due to the higher coefficient of expansion. If more than two joints are specified, a
cable or expansion limiting device is required to keep the ends from separating.
Utility Blockouts – Blockouts shall be provided in all structural members that
prohibit the passage of utilities, such as girder end diaphragms, pier crossbeams,
and intermediate diaphragms. These blockouts shall be large enough to fit deflection
fittings, and shall be parallel to the utility. For multiple utilities, a note shall be added
to the plans that the deflection fittings shall be staggered such that no fitting is located
adjacent to another, or the blockouts shall be designed to fit both fittings. Expansion
fittings shall be staggered.
Gas Lines or Volatile Fluids – Pipelines carrying volatile fluids through a bridge
superstructure shall be designed by the utility company in accordance with WAC
480-93, Gas Companies—Safety, and Minimum Federal Safety Standard, Title 49
Code of Federal Regulations (CFR) Section part 192. WAC 468-34-210, Pipelines—
Encasement, describes when casing is required for carrying volatile fluids across
structures. Generally, casing is not required for pipelines conveying natural gas per the
requirements of WAC 468-34-210. If casing is required, then WAC 468-34-210 and
WAC 480-93-115 shall be followed.
Water Lines – Transverse support or bracing shall be provided for all water lines to
carry Strength and Extreme Event Lateral Loading. Fire control piping is a special
case where unusual care must be taken to handle the inertial loads and associated
deflections. The Utility Engineer shall be involved in the design of supports resisting
dynamic action loads and deflections.
In box girders (closed cell), a rupture of a water line will generally flood a cell
before emergency response can shut down the water main. This shall be designed
for as an Extreme Event II load case, where the weight of water is a dead load (DC).
Additional weep holes or open grating shall be considered to offset this Extreme Event
(see Figure 10.8.3-1). Full length casing extending 10-feet beyond the end of the
bridge approach slab shall be considered as an alternate to additional weep holes or
open grating.
Sewer Lines – Normally, an appropriate encasement pipe is required for sewer lines
on bridges. Sewer lines shall meet the same design criteria as waterlines. See the utility
agreement or the Hydraulic Section for types of sewer pipe material typically used.
Electrical (Power and Communications) – Telephone, television cable, and power
conduit shall be galvanized Rigid Metal Conduit (RGS) or Rigid Polyvinyl Chloride
Conduit (PVC). Where such conduit is buried in concrete curbs or barriers or has
continuous support, such support is considered to be adequate. Where hangers or
brackets support conduit at intervals, the maximum distance between supports shall be
5 feet.

Page 10-50

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

10.8.3

Signs, Barriers, Approach Slabs, and Utilities

Box/Tub Girder Bridges
Utilities shall not be placed inside reinforced concrete box girders less than 4 feet
inside clear height and all precast prestressed concrete tub girders because reasonable
access cannot be provided. Utilities shall be located between girders or under bridge
deck soffit in these cases. Inspection lighting, access and ventilation shall always be
provided in girder cells containing utilities. Refer to the concrete and steel chapters for
additional details.
Continuous Support and Concrete Pedestals – Special utilities (such as water or
gas mains) in box girder bridges shall use concrete pedestals. This allows the utility
to be placed, inspected, and tested before the deck is cast. Concrete pedestals consist
of concrete supports formed at suitable intervals and provided with some type of
clamping device. Continuous supports shall be
avoided due to the very high cost and


additional dead load to the structure.




























































 


































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
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
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Concrete Utility Supports



Figure 10.8.3-1

10.8.4

Traffic Barrier Conduit
All new bridge construction shall install two 2-inch galvanized Rigid Metal Conduit
(RGS) or Rigid Polyvinyl Chloride Conduit (PVC) in the traffic barriers. These
conduits generally carry wiring for Traffic Signals (TS) and Lighting (LT). Other
wiring may be installed or the conduit may be used for future applications. PVC
conduit may be used only in stationary-form barriers, and will connect to RGS using
a PVC adaptor when exiting the barrier. RGS conduit may be used in stationary-form
barriers, but it shall be used in slipform barriers.
Each conduit shall be stubbed-out into its own concrete junction box at each corner
of the bridge. The Bridge Plans must show the placement of the conduits to clear the
structure or any foreseeable obstructions.

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The galvanized steel conduit shall be wrapped with corrosion resistant tape at least one
foot inside and outside of the concrete structure, and this requirement shall be so stated
on the plans. The corrosion resistant tape shall be 3M Scotch 50, Bishop 5, Nashua
AVI 10, or approved equal. The usual location of the conduit throughout the remainder
of the bridge should be in the traffic barrier.
Pull boxes shall be provided within the barrier for each conduit at each end of the
bridge and at a maximum spacing of 180 feet. For fiber optics only, spacing shall not
exceed 360 feet. The pull box size shall conform to the specifications of the National
Electric Code or be a minimum of 8 inches by 8 inches by 18 inches to facilitate
pulling of wires. Galvanized steel pull boxes (or junctions boxes) shall meet the
specifications of the “NEMA Type 4X” standard for stationary-form barrier, shall meet
the specifications of the “NEMA 3R” and be adjustable in depth for slip form barrier,
and the NEMA junction box type shall be stated on the plans. Stainless steel pull boxes
may be used as an option to the galvanized steel.
In the case of existing bridges, an area 2 feet in width shall be reserved for conduit
beginning at a point either 4 feet or 6 feet outside the face of usable shoulder. The
fastening for and location of attaching the conduit to the existing bridge shall be
worked out on a job-by-job basis.
10.8.5

Conduit Types
All electrical conduits shall be galvanized Rigid Metal Conduit (RGS) or Rigid
Polyvinyl Chloride Conduit (PVC).
Steel Pipe – All pipe and fittings shall be galvanized except for special uses.
PVC Pipe – PVC pipe may be used with suitable considerations for deflection,
placement of expansion fittings, and of freezing water within the conduits. PVC pipe
shall not be placed in concrete traffic barriers when the slip form method is used due to
damage and pipe separation that often occurs during concrete placement.

10.8.6

Utility Supports
The following types of supports are generally used for various utilities. Selection of
a particular support type shall be based on the needs of the installation and the best
economy. All utility installations shall address temperature expansion in the design of
the system or expansion devices.
Utility supports shall be designed so that a failure will not result in damage to the
bridge, the surrounding area, or be a hazard to traffic. Utility supports shall be designed
so that any loads imposed by the utility installation do not overstress the conduit,
supports, bridge structure, or bridge members.
Designs shall provide longitudinal and transverse support for loads from gravity,
earthquakes, temperature, inertia, etc. It is especially important to provide transverse
and longitudinal support for inserts that cannot resist moment.
The Bridge Engineer shall request calculations from the utility company for any
attachment detail that may be questionable. Utility attachments, which exert moments
or large forces at the supports, shall be accompanied by at least one set of calculations
from the utility company. Bridge attachments designed to resist surge forces shall
always be accompanied by calculations.

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Concrete Embedment – This is the best structural support condition and offers
maximum protection to the utility. Its cost may be high for larger conduit and the
conduit cannot be replaced.
Pipe Hangers – Utility lines shall be suspended by means of cast-in-place inserts,
whenever possible. This is the most common type of support for utilities to be hung
under the bridge deck. This allows the use of standard cast-in-place inserts and is
very flexible in terms of expansion requirements. For heavy pipes over traffic (10″
water main or larger), a Safety Factor of 1.5 should be used to resist vertical loads
for Strength Design. This is to avoid complete failure of the utility hanger system by
failure of one hanger. Vertical inserts will not provide resistance to longitudinal forces.
Longitudinal and transverse supports shall be provided for ITS conduits. Vertical
supports shall be spaced at 5 foot maximum intervals for telephone and power
conduits, and at a spacing to resist design loads for all other utilities.
When 3/4″ or 7/8″ diameter hanger rods are suspended from cast-in-place inserts, at
least three of the following inserts shall be identified: Cooper B-Line B22-I Series,
Unistrut 3200 Series, Powerstrut 349 Series, Halfen HT5506 or similar. The specific
cast-in-place insert within each series shall be identified based on the required length
of insert. The cast-in-place insert shall be at least 6″ long and hot dipped galvanized
in accordance with AASHTO M 111 or AASHTO M 232.
The insert shall not interfere with reinforcement in the bridge deck. The inserts shall
be installed level longitudinally and transversely. When the superelevation of the
roadway is not significant, a single, long insert may be used to support multiple hanger
rods. When the superelevation becomes significant, a single insert may be used for
each hanger.
Occasionally large diameter utilities require pipe rolls that only fit on 1″ diameter
hanger rods. When 1″ diameter hanger rods are required, the Anvil Fig. 286
and Unistrut P3246 insert shall be used. The designer shall only specify this insert
when absolutely necessary.
The Bridge Engineer shall verify that the cast-in-place insert has sufficient capacity
to support the loads from the hanger rod.
Transverse supports may be provided by a second hanger extending from a girder or
by a brace against the girder. The Bridge Standard Drawing 10.8-A1-1 and 10.8-A1-2
depict typical utility support installations and placement at abutments and diaphragms.
Transverse supports shall, at a minimum, be located at every other vertical support.

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10.9

Chapter 10

Utility Review Procedure for Installation on Existing Bridges
It is the responsibility of the Region Utilities Engineer to forward any proposed
attachments to existing bridges to the Bridge Preservation Office. The Bridge
Preservation Office is responsible for reviewing only those details pertaining to the
bridge crossing such as attachment details or trenching details adjacent to bridge piers
or abutments.
The Bridge Preservation Office reviews proposed utility attachments and either
approves the attachment or returns for correction (RFC). A current file for most utility
attachments is maintained in the Bridge Preservation Office. The turnaround time for
reviewing the proposals should not exceed four weeks.
The Region determines the number of copies to be returned. Most Regions send
five copies of the proposed utility attachment. If the proposal is approved, Bridge
Preservation will file one copy in the utility file and return four marked copies. If it
has been returned for correction or not approved, one copy is placed in the utility file
and two marked copies are returned, thru the Region, to the utility. See Section 10.9.1,
“Utility Review Checklist.”
Utility attachments, which exert moments or large forces at the supports, shall be
accompanied by at least one set of calculations from the utility company. Bridge
attachments designed to resist surge forces shall always be accompanied by
calculations. The connection details shall be designed to successfully transfer all forces
to the bridge without causing overstress in the connections or to the bridge members
to which they are attached. For large utilities, the bridge itself shall have adequate
capacity to carry the utility without affecting the live load capacity.
The engineer may request calculations from the utility company for any attachment
detail that may be questionable. All plans, details, and calculations shall be stamped,
signed, and dated by a Professional Engineer licensed in the State of Washington.
Additionally, for heavier utilities, such as waterlines or sewer lines, the engineer may
request a load rating of the structure, which shall be stamped, signed, and dated by a
licensed professional engineer in the state of Washington to follow the guidelines of
Chapter 13. The ratings shall be based solely on the engineer of record calculations.
Guidelines for Utility Companies
Detailing guidelines for utility companies to follow when designing utility attachments
are listed in WSDOT Form 224-047, “General Notes and Design Criteria for Utility
Installations to Existing Bridges.” See Figure 10.8.1-1. See Section 10.8 for other
requirements, which include, but are not limited to: design of utility, material used, and
spacing of supports.
Water lines and sewer lines installed within box girders shall have full length casing
extending 10-feet beyond the end of the bridge approach slab. The casing shall be
sufficient to prevent the flooding of a cell upon a utility line rupture.

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Guidelines for Column Attachments
The following guidelines shall be followed for installing attachments to columns.
• Attachments on round columns may be either drilled and bolted or banded.
• Attachments on non-circular column shapes shall be drilled and bolted.
• Only percussion drilling methods shall be allowed on bridge columns, and only
for small diameter resin bonded anchor installation (0.50″ diameter max.). Drilling
will normally result in blind holes, and these holes shall be patched with material
conforming to Standard Specifications Section 6-02.3(20).
• Drilling into prestressed or post-tensioned concrete elements is not permitted.
Some WSDOT bridges utilize prestressed columns.
Any proposed conduit installation on a WSDOT bridge structure shall be reviewed
and approved by the Risk Reduction Engineer in the Bridge Preservation Office. If the
conduit installation originates via a change order, then the Headquarters Construction
Office may provide approval, and shall inform the Risk Reduction Engineer of
the decision.
10.9.1

Utility Review Checklist
This checklist applies to all proposed utility attachments to existing bridges.
1. Complete cursory check to become familiar with the proposal.
2. Determine location of existing utilities.
a. Check Bridge Inspection Report for any existing utilities.
b. Check Bridge Preservation’s utility file for any existing utility permits or
franchises and possible as-built plans.
c. Any existing utilities on the same side of the structure as the proposed utility
shall be shown on the proposal.
3. Review the following with all comments in red:
a. Layout that includes dimension, directions, SR number and bridge number.
b. Adequate spacing of supports.
c. Adequate strength of supports as attached to the bridge (calculations may
be necessary).
d. Maximum design pressure and regular operating pressure for pressure
pipe systems.
e. Adequate lateral bracing and thrust protection for pressure pipe systems.
f. Does the utility obstruct maintenance or accessibility to key bridge
components?
g. Check location (elevation and plan view) of the utility with respect to pier
footings or abutments. If trench limits encroach within the 45° envelope from
the footing edge, consult the Materials Lab.
h. Force mains or water flow systems may require encasement if they are in
excavations below the bottom of a footing.

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4. Write a letter of reply or email to the Region so a copy will be returned to you
indicating the package has been accepted and sent out.
5. Stamp and date the plans using the same date as shown on the letter of reply
or email.
6. Create a file folder with the following information:
a. Bridge no., name, utility company or utility type, and franchise or permit
number.
b. One set of approved plans and possibly one or two pages of the original
design plans if necessary for quick future reference. Previous transmittals
and plans not approved or returned to correction should be discarded to avoid
unnecessary clutter of the files.
c. Include the letter of submittal and a copy of the letter of reply or email after
it has been accepted.
7. Give the complete package to the Design Unit Manager for review and place the
folder in the utility file after the review.

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10.10

Signs, Barriers, Approach Slabs, and Utilities

Drilled Anchors For Permanent Attachments
WSDOT allows conventional drilled anchors systems (resin bonded anchors and
undercut anchors) for permanent attachments in many aspects of bridge design,
including the permanent cyclical or sustained tension applications listed below.
• Sign structures mounted to the sides of bridges with a maximum cantilever length
or total span of 10 feet.
• Light standards with a maximum cantilever length of 16 feet.
• Sign structures with a supporting, round or rectangular, post or beam with
a maximum dimension of 8 inches.
• Retrofitted corbels for bridge approach slabs.
• Supporting utilities under bridges, including water pipes, electrical conduit and
other utility piping systems.
For resin bonded anchors used in permanent sustained tension applications, the
adhesive anchor systems shall have successfully completed testing for long term
sustained load performance in accordance with ACI 355.4. Depending on the specific
application of the permanent attachment, additional quality assurance performance
measures such as field proof testing of production anchors in accordance with
ACI 355.4 should be included in the design. Resin bonded anchors shall not be
used in monotube sign structure, sign structure truss, and mast arm type signal
standard applications.
Fast set resin bonding materials shall not be used for resin bonded anchors.
For carbon steel undercut anchors, hot-dip galvanized components are preferred,
but not currently available from suppliers. Undercut anchors with electroplated zinc
coatings are not considered equivalent or better and shall not be used. Therefore,
stainless steel undercut anchors are the preferred option. Depending on the specific
application of the permanent attachment, additional quality assurance performance
measures such as field proof testing of production anchors in accordance with ACI
355.2 should be included in the design.
The design procedure for adhesive and undercut anchors shall be in accordance with
ACI 318 Chapter 17, and system qualification testing requirements in accordance with
ACI 355.4 and ACI 355.2, respectively.
Expansion anchors and mechanical anchors are not allowed for any permanent
applications, except for specific connection details previously approved by the Bridge
and Structures Office for precast concrete panel faced structural earth walls as low
risk applications.
Cast-in-place concrete anchors remain the preferred option for bridge applications.

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10.11

Chapter 10

Drainage Design
Even though it is rare that poor drainage is directly responsible for a structural failure,
it still must be a primary consideration in the design. Poor drainage can cause problems
such as ponding on the roadway, erosion of abutments, and deterioration of structural
members. Collecting the runoff and transporting it away from the bridge can prevent
most of the problems. Proper geometrics during the preliminary stage is essential in
order to accomplish this. The Hydraulics Branch recommends placing the bridge deck
drainage off of the structure. Therefore, the Bridge Design Section has adopted the
policy that all expansion joints shall be watertight.
Geometrics
Bridges shall have sufficient transverse and longitudinal slopes to allow the water
to run quickly to the drains. A transverse slope of .02′/ft and longitudinal slope of
0.5 percent for minimum valves are required. Avoid placing sag vertical curves and
superelevation crossovers on the structure that could result in hydroplaning conditions
or, in cold climates, sheets of ice from melting snow. The use of unsymmetrical vertical
curves may assist the designer in shifting the low point off the structure.
Hydrology
Hydrological calculations are made using the rational equation. A 10-year storm event
with a 5-minute duration is the intensity used for all inlets except for sag vertical
curves where a 50-year storm intensity is required.
On Bridge Systems
Drains shall only be placed on bridge structures when required. If required, the first
preference is to place 5-inch diameter pipe drains that have no bars and drop straight
to the ground. At other times, such as for steel structures, the straight drop drain is
unacceptable and a piping system with bridge drains is required. The minimum pipe
diameter shall be 6 inches with no sharp bends within the system. The Hydraulics
Branch shall be contacted to determine the type of drain required (preferably Neenah).
Construction
Bridge decks have a striated finish in accordance with the Standard Specifications
Section 6-02.3(10)D5, however, the gutters have an untextured finish (steel trowel) for
a distance of 2 feet from the curb. This untextured area provides for smooth gutter flow
and a Manning n value of .015 in the design.

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10.12

Signs, Barriers, Approach Slabs, and Utilities

Bridge Security

10.12.1 General
Security based bridge design and its direct correlation to modern social issues is
addressed in this section. Criminal activity, illegal encampments, graffiti, hindrance
to economic development and public eyesore create unwanted expensive. They also
pose public health concerns and safety hazards for State Maintenance and Operations
practices. The issue exists in urban areas as well as rural and recreational locales.
Bridges are dominant structures in landscapes. They are held to a higher standard of
design due to their influence on communities, where economic and social settings are
affected by their quality. Initial project cost savings may quickly be overshadowed by
increased externalized costs. These externalized costs are born by local municipalities
and businesses as well as other departments within WSDOT.
WSDOT bridge inspectors are required to inspect all bridges at least once every
24 months. The presence of the illegal encampments, as well as garbage, hypodermic
needles, and feces often makes it impossible to do a close, hands-on inspection of the
abutments and bearings of bridges. The Bridge Preservation Office has requested that
maintenance clean up transient camps when it becomes difficult or impossible to do
an adequate inspection of the bridges. Campfires set by the homeless have also caused
damage to bridges.
Bridge Maintenance Crews also face the same difficulty when they need to do repair
work on bridges in the urban area. Clean up requires (per law) posting the bridge
seventy-two hours prior to any work. Material picked up is tagged, bagged, and stored
for retrieval. Often the offenders are back the next day.
10.12.2 Design
Design is determined on a case by case basis using two strategies. These strategies are
universally accepted best practices. The first, Crime Prevention through Environmental
Design (CEPTD), is a multi-disciplinary approach to deterring criminal behavior.
The second, Context Sensitive Design (CSS), is also multi-disciplinary and focuses
on project development methods. Multi-disciplinary teams consist of engineers and
architects but may include law enforcement, local businesses, social service providers,
and psychologists.
A. CPTED principals are based upon the theory that the proper design and effective
use of the built environment can reduce crime, reduce the fear of crime, and
improve the quality of life. Built environment implementations of CPTED
seek to dissuade offenders from committing crimes by manipulating the built
environment in which those crimes proceed from or occur. The six main concepts
are territoriality, surveillance, access control, image/maintenance, activity support
and target hardening. Applying all of these strategies is key when preventing crime
in any neighborhood or right-of-way.
Natural surveillance and access control strategies limit the opportunity for crime.
Territorial reinforcement promotes social control through a variety of measures.
These may include enhanced aesthetics or public art. Image/maintenance and
activity support provide the community with reassurance and the ability to stop
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crime by themselves. Target hardening strategies may involve fencing or concrete
enclosures or they may include all techniques to resolve crime or chronic trespass
into one final step.
B. WSDOT implements FHWA’s CSS design development principles through
Executive Order E 1028. The CSS methods require designers to consider the
physical, economic, and social setting of a project. Stakeholder’s interests are to be
accounted for; including area residents and business owners.
10.12.3 Design Criteria
New bridges need to address design for the environment by basic criteria:
• Slopes under bridges need to be steep; around a 1:1 slope, and hardened with
something like solid concrete so that flat areas cannot be carved into the hillside.
Flat areas under bridge superstructures attract inappropriate uses and should
be omitted.
• Illegal urban campers have been known to build shelters between the concrete
girders. Abutment walls need to be high enough that they deny access to the
superstructure elements. When it is not feasible to design for deterrence the
sites need to be hardened with fencing buried several feet into the soil or with
solid concrete walls. See Figures 14.2.3a and 14.2.3b for high security fence and
concrete wall examples.
• Regular chain link is easy cut, therefore stouter material needs to be specified.
• Landscape design should coordinate with region or headquarters landscape
architects. Areas need to be visible to law enforcement.
‘High security’ proprietary fence designs may be employed, or unique case-by-case
custom designs may be required. Where required, coordinate with the State Bridge and
Structures Architect.

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10.13

Signs, Barriers, Approach Slabs, and Utilities

Temporary Bridges

10.13.1 General
Temporary bridges are defined as bridges that are in service for 5 years or less. Any
bridge that is expected to be in service for more than five years shall be designed using
the requirements for permanent structures. These requirements apply to all temporary
bridges regardless of the delivery contracting methods.
The approaches to the temporary bridge, including but not limited to, slopes, reinforced
slopes, and retaining walls, shall be designed in accordance with the WSDOT
Geotechnical Design Manual M 46-03.
10.13.2 Design
Temporary bridges shall be designed in accordance with the requirements of the
current editions of:
AASHTO LRFD and interims
AASHTO SEISMIC
WSDOT Bridge Design Manual M 23-50, including all design memorandums
WSDOT Geotechnical Design Manual M 46-03
A. Design Requirements
The design of the temporary bridge shall not include an additional future overlay
of 25 pound per square foot.
The live loading of the temporary bridge may be reduced to 75 percent of the
HL-93 loading, except the deck design shall us 100 percent of the HL-93 loading.
B. Seismic Design Requirements
The seismic design of temporary bridges shall be in accordance with the
requirements of the current edition of AASHTO SEISMIC, except the design
response spectra shall be reduced by a factor not greater than 2.5.
The minimum support length provisions shall apply to all temporary bridges.
The Seismic Design Category (SDC) of the temporary bridge shall be obtained
on the basis of the reduced/modified response spectrum except that a temporary
bridge classified in SDC B, C, or D based on the unreduced spectrum cannot be
reclassified to SDC A based on the reduced/modified spectrum.
C. Deck Design Requirements
Traffic barriers for temporary bridges shall be designed in accordance with the
requirements of the current edition of AASHTO LRFD, but not less than TL-3
collision load requirements. The TL demand may be adjusted on a case-by-case
basis for vehicle size and speed per AASHTO LRFD Tables 13.7.2-1 and 2.
The fall restraint specifications of WAC 296-155-24615 Section 2a requiring
minimum vertical height of thirty-nine inches for traffic barriers shall be considered
for temporary bridges.
Concrete bridge deck thickness may be reduced to 7 inches for concrete
superstructure, and to 7½ inches for steel superstructures.
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Epoxy coating requirement for bridge deck reinforcement may be waived for
temporary bridges with 2 inch min cover for the top mat of reinforcement.
The driving surface of the temporary bridge shall be durable, skid resistant deck,
with an initial skid number of at least 35 and maintaining a skid number of 26
minimum, in accordance with AASHTO T 242. The Contractor shall maintain the
temporary bridge, including the driving surface, for the life of the temporary bridge
in the project.
D. Superstructure Design Requirements
A 3 inch minimum HMA overlay could be used for temporary bridges made of
adjacent precast concrete members.
Steel temporary bridges need not be painted.
Fatigue need not be checked for temporary bridges with steel superstructure.
All welding, repair welding, and welding inspection, of steel components of the
temporary bridge shall conform to the Standard Specifications Section 6-03.3(25)
and 6-03.3(25)A requirements specified for steel bridges.
Allowable tensile stress for precast-prestressed concrete girders under service limit
state load combinations per AASHTO LRFD Article 5.9.4.2.2 may be used in lieu
of those specified in Section 5.2.1C.
E. Foundation Design Requirements
Pile types such as precast, prestressed concrete piles, steel H piles, timber piles,
micropiles and steel pipe piles may be used for temporary bridges.
Soldier pile wall with treated timber lagging may be used for temporary bridges.
10.13.3 NBI Requirements
Temporary or re-commissioned bridges used as a detour and in-service longer the 90
days shall receive full NBIS (all SI&A data; ex., NBIS inspection, load ratings and
scour evaluation). All SI&A data shall be submitted to the Washington State NBI
data base within 90 days of opening to vehicle traffic. An “open” bridge is defined as
a bridge that is near substantial completion with general highway traffic accessing/
operating on the bridge in a configuration that is the final planned configuration.
Phased construction stages, if carrying traffic for 90 days or longer shall fall into these
criteria.
Bridges open less than 90 days will need regular “safety” type inspections to ensure the
safe operation of traffic on the bridge.
Contracts are to clearly identify the owner and who is responsible for all of this
NBIS criteria.
Load ratings for legal trucks and special hauling vehicles are required for temporary
and bridges constructed in phased stages. The minimum rating factor shall not be less
than 1.0.
10.13.4 Submittal Requirements
The Contractor shall submit drawings and copies of supporting design calculations
of the temporary bridge to the Engineer for approval in accordance with Standard
Page 10-62

WSDOT Bridge Design Manual M 23-50.17
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Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

Specifications Section 6-01.9. The submittal shall include an erection plan and
procedure in accordance with Standard Specifications Section 6-03.3(7)A.
Submittals for temporary bridges with total length of more than 200 ft shall be stamped
and signed by a Washington State registered Structural Engineer (SE) in accordance
with the requirements of WAC 196-23.
The Contractor shall construct the temporary bridge in accordance with the working
drawings and erection plan as approved by the Engineer, environmental permit
conditions specified in Section 1-07.5 as supplemented in the Special Provisions and
as shown in the Plans, and in accordance with the details shown in the Plans.

WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-63

Signs, Barriers, Approach Slabs, and Utilities

10.14

Chapter 10

Bridge Standard Drawings
10.1-A1-1
10.1-A1-2
10.1-A1-3

Monotube Sign Bridge Layout
Monotube Sign Bridge Structural Details 1
Monotube Sign Bridge Structural Details 2

10.1-A2-1
10.1-A2-2
10.1-A2-3

Monotube Cantilever Layout
Monotube Cantilever Structural Details 1
Monotube Cantilever Structural Details 2

10.1-A3-1
10.1-A3-2
10.1-A3-3

Monotube Sign Structure Balanced Cantilever Layout
Monotube Balanced Cantilever Structural Details 1
Monotube Balanced Cantilever Structural Details 2

10.1-A4-1
10.1-A4-2
10.1-A4-3

Monotube Sign Structures Foundation Type 1 Sheet 1 of 2
Monotube Sign Structures Foundation Type 1 Sheet 2 of 2
Monotube Sign Structures Foundation Types 2 and 3

10.1-A5-1
10.1-A5-2
10.1-A5-3

General Notes
Monotube Sign Structure Miscellaneaous Details
Monotube Sign Structure Single Slope Traffic Barrier Shaft Cap

10.1-A6-1
10.1-A6-2
10.1-A6-3
10.1-A6-4
10.1-A6-5

Bridge Mounted Sign Bracket Example Layout
Bridge Mounted Sign Bracket Geometry
Bridge Mounted Sign Bracket Details 1 of 3
Bridge Mounted Sign Bracket Details 2 of 3
Bridge Mounted Sign Bracket Details 3 of 3

10.2-A1-1
10.2-A1-2
10.2-A1-3

Traffic Barrier – Shape F Details 1 of 3
Traffic Barrier – Shape F Details 2 of 3
Traffic Barrier – Shape F Details 3 of 3

10.2-A2-1
10.2-A2-2
10.2-A2-3

Traffic Barrier – Shape F Flat Slab Details 1 of 3
Traffic Barrier – Shape F Flat Slab Details 2 of 3
Traffic Barrier – Shape F Flat Slab Details 3 of 3

10.2-A3-1
10.2-A3-2
10.2-A3-3

Traffic Barrier – Single Slope Details 1 of 3
Traffic Barrier – Single Slope Details 2 of 3
Traffic Barrier – Single Slope Details 3 of 3

10.2-A4-1
10.2-A4-2
10.2-A4-3

Pedestrian Barrier Details 1 of 3
Pedestrian Barrier Details 2 of 3
Pedestrian Barrier Details 3 of 3

10.2-A5-1A
10.2-A5-1B
10.2-A5-2
10.2-A5-3

Traffic Barrier – Shape F 42″
Traffic Barrier – Shape F 42″
Traffic Barrier – Shape F 42″
Traffic Barrier – Shape F 42″

Details 1 of 3 (TL-4)
Details 1 of 3 (TL-5)
Details 2 of 3
Details 3 of 3

10.2-A6-1A Traffic Barrier – Single Slope 42″ Details 1 of 3 (TL-4)
10.2-A6-1B Traffic Barrier – Single Slope 42″ Details 1 of 3 (TL-5)

Page 10-64

WSDOT Bridge Design Manual M 23-50.17
June 2017

Chapter 10

Signs, Barriers, Approach Slabs, and Utilities

10.2-A6-2
10.2-A6-3

Traffic Barrier – Single Slope 42″ Details 2 of 3
Traffic Barrier – Single Slope 42″ Details 3 of 3 (TL-4 and TL-5)

10.2-A7-1
10.2-A7-2
10.2-A7-3

Traffic Barrier – Shape F Luminaire Anchorage Details
Traffic Barrier – Single Slope Luminaire Anchorage Details
Pedestrain Barrier Luminaire Anchorage Details

10.4-A1-1
10.4-A1-2
10.4-A1-3
10.4-A1-4
10.4-A1-5

Thrie Beam Retrofit Concrete Baluster
Thrie Beam Retrofit Concrete Railbase
Thrie Beam Retrofit Concrete Curb
WP Thrie Beam Retrofit SL1 Details 1 of 2
WP Thrie Beam Retrofit SL1 Details 2 of 2

10.4-A2-1
10.4-A2-2
10.4-A2-3

Traffic Barrier – Shape F Rehabilitation Details 1 of 3
Traffic Barrier – Shape F Rehabilitation Details 2 of 3
Traffic Barrier – Shape F Rehabilitation Details 3 of 3

10.5-A1-1
10.5-A1-2

Bridge Railing Type Pedestrian Details 1 of 2
Bridge Railing Type Pedestrian Details 2 of 2

10.5-A2-1
10.5-A2-2

Bridge Railing Type BP Details 1 of 2
Bridge Railing Type BP Details 2 of 2

10.5-A3-1
10.5-A3-2

Bridge Railing Type S-BP Details 1 of 2
Bridge Railing Type S-BP Details 2 of 2

10.5-A4-1
10.5-A4-2

Pedestrian Railing Details 1 of 2
Pedestrian Railing Details 2 of 2

10.5-A5-1
10.5-A5-2
10.5-A5-3
10.5-A5-4

Bridge Railing Type Chain Link Snow Fence
Bridge Railing Type Snow Fence Details 1 of 2
Bridge Railing Type Snow Fence Details 2 of 2
Bridge Railing Type Chain Link Fence

10.6-A1-1
10.6-A1-2
10.6-A1-3

Bridge Approach Slab Details 1 of 3
Bridge Approach Slab Details 2 of 3
Bridge Approach Slab Details 3 of 3

10.6-A2-1
10.6-A2-2

Pavement Seat Repair Details
Pavement Seat Repair Details

10.8-A1-1
10.8-A1-2

Utility Hanger Details
Utility Hanger Details

10.11-A1-1 Bridge Drain Modification
10.11-A1-2 Bridge Drain Modification for Types 2 thru 5

WSDOT Bridge Design Manual M 23-50.17
June 2017

Page 10-65

Signs, Barriers, Approach Slabs, and Utilities

10.15

Chapter 10

References
AASHTO Guide Specification for LRFD Seismic Bridge Design, 2nd Edition (2011),
Washington DC.
AASHTO, 1st Edition (2015), Washington DC.
AASHTO Standard Specifications for Highway Bridges, 17th Edition (2002),
Washington DC.
ACI 318-14 (2014) “Building Code Requirements for Structural Concrete and
Commentary,” American Concrete Institute, Farmington Hills, MI.
ACI 355.2-07 (2007) “Qualification of Post-Installed Mechanical Anchors in Concrete
and Commentary,” American Concrete Institute, Farmington Hills, MI.
ACI 355.4-11 (2014) “Qualification of Post-Installed Adhesive Anchors in Concrete
and Commentary,” American Concrete Institute, Farmington Hills, MI.
NCHRP Report 230, “Recommended Procedures for the Safety Performance
Evaluation of Highway Appurtenances”, Transportation Research Board, 1991,
Washington DC.
NCHRP Report 350, “Recommended Procedures for the Safety Performance
Evaluation of Highway Features”, Transportation Research Board, 1993,
Washington DC.
NCHRP Report 663, “Design of Roadside Barrier Systems Placed on MSE Retaining
Walls”, NCHRP Project 22-20, Transportation Research Board, 2010, Washington DC.
WSDOT Design Manual M 22-01
WSDOT Geotechnical Design Manual M 46-03
WSDOT Standard Plans M 21-01
WSDOT Standard Specifications for Road, Bridge, and Municipal Construction
(Standard Specifications) M 41-10
WSDOT E 1028 Context Sensitive Solutions Executive Order
Newman, O. Defensible Space: Crime Prevention Through Urban Design. New York:
Macmillan. 1972.
Jacobs, Jane. The Death and Life of Great American Cities. New York:
Random House. 1961.

Page 10-66

WSDOT Bridge Design Manual M 23-50.17
June 2017

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