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

Traction tires are a special type of tire

manufactured with at least 1/8 of an inch tread. Traction tires are usually marked with a mountain/snowflake symbol, the letters M+S or “All Season.”

Carry chains, practice before leaving

Requiring chains keeps traffic moving during storms rather than closing a pass or roadway.

Prep your car. Fill up your gas tank,

pack jumper cables, ice scraper, warm clothing, snacks and water.