Seismic design

Find seismic design and retrofit information for new and existing structures.

Related manual chapters

Chapter 4 - Seismic Design and Retrofit (PDF 4.7MB) provides guidance for expected bridge performance and post-earthquake service levels. This chapter details WSDOT additions and modifications to the AASHTO Guide Specifications for LRFD Seismic Bridge Design. It also includes design requirements for widening projects, retrofit projects and walls and buried structures.

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.