Preliminary design, plan preparation & specifications for bridges & structures

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.

  • There are currently no design memorandums related to this topic

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).

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166,800 electric vehicle

registrations in Washington in 2023, up from 114,600 in 2022.

87 wetland compensation sites

actively monitored on 918 acres in 2023.

25,000 safe animal crossings

in the Snoqualmie Pass East Project area since 2014.