Bridge Design Manual LRFD

Publication Number
M 23-50
Publication Version
M 23-50.20
Publication Date
Manual Manager
Scott Sargent, 360-705-7753,
Bridge and Structures Office, Engineering and Regional Operations Division


This manual has been prepared to provide Washington State Department of Transportation (WSDOT) bridge design engineers with a guide to the design criteria, analysis methods, and detailing procedures for the preparation of highway bridge and structure construction plans, specifications, and estimates.

Bridge Design Manual Memorandums 

Bridge design memorandums are issued as interim updates to the Bridge Design Manual. 

Active design memorandums supersede the contents of the Bridge Design Manual and are currently in force. View Active Bridge Design Manual memorandums

Inactive memorandums provide historical context and background on design policies incorporated into the Bridge Design Manual. View Inactive Bridge Design Manual memorandums.

Individual Chapters

Contents (PDF 278KB)
Foreword (PDF 96KB)

Chapter 1 General Information (PDF 1.0MB)
Chapter 2 Preliminary Design (PDF 3.6MB)
Chapter 3 Loads (PDF 906KB)
Chapter 4 Seismic Design and Retrofit (PDF 4.7MB)
Chapter 5 Concrete Structures (PDF 18.2MB)
Chapter 6 Structural Steel (PDF 2.2MB)
Chapter 7 Substructure Design (PDF 2.4MB)
Chapter 8 Walls and Buried Structures (PDF 3.0MB)
Chapter 9 Bearings and Expansion Joints (PDF 1.5MB)
Chapter 10 Sign, Barriers, Approach Slabs, and Utilities (PDF 8.6MB)
Chapter 11 Detailing Practice (PDF 1.4MB)
Chapter 12 Quantities, Costs, and Specifications (PDF 2.5MB)
Chapter 13 Bridge Load Rating (PDF 1.9MB)
Chapter 14 Accelerated and Innovative Bridge Construction (PDF 2.5MB)
Chapter 15 Structural Design Requirements for Design-Build Contracts (PDF 1.5MB)

Revision History

M 23-50.20

 M 23-50.19 

M 23-50.18 

M 23-50.17  

M 23-50.16 

M 23-50.15 

M 23-50.14

M 23-50.13 

M 23-50.12

M 23-50.11

M 23-50.10

M 23-50.09 

M 23-50.08

M 23-50.07 

M 23-50.06 

M 23-50.05 

M 23-50.04 

M 23-50.03 

M 23-50.02 

M 23-50.01 February 2007

November 2006

September 2006

August 2006

July 2005

April 2005

August 2002

8,683 animals crossed the Snoqualmie Pass East Project area

as recorded by WSDOT and partners in 2020 and 2021.

46% increase in Amtrak Cascades ridership to 251,000 passengers

in 2021 compared to 172,000 in 2020.

Nine wetland and stream mitigation sites across 32.7 acres added

to our monitoring program in 2021 to help offset climate change impacts.