Preliminary design, plan preparation & specifications

Find information on preliminary studies, planning criteria, structure type selection and aesthetic consideration. Also find guidance for preparation of bridge plans, specifications and estimates.

Design memorandum

Design memorandum are issued as interim updates to the Bridge Design Manual. Active design memorandums supersede the Bridge Design Manual contents and are currently enforced.

Related manual chapters 

Chapter 1 - General Information (PDF 1.0MB)  provides background, organizational information, roles and responsibilities and quality control procedures.
Chapter 2 - Preliminary Design (PDF 3.6MB) provides guidance and criteria for developing preliminary designs and plans.

Bridge Design Manual 

Complete Bridge design guidance is found in the Bridge Design Manual (M 23-50).

See all manuals and standards

14 fish passage projects were completed in 2020

improving access to 54.2 miles of upstream habitat.

11,959 incidents responded to

by WSDOT’s incident Response teams during second quarter of 2021, 15% more than same quarter in 2020.

41 Pre-existing Funds Projects Advertised

during the eighth quarter of the 2019-2021 biennium.