Preserving our roads & bridges

Learn how we maintain our state's highway system to keep people safe and goods moving 24-hours-a-day, 365-days-a-year.

We oversee the day-to-day needs of maintaining our state's highway system, including:

  • 20,679 highway lane miles (includes ramps, collectors and special use lanes).
  • More than 3,000 bridges.
  • 1,100 traffic signal systems.
  • 10 major mountain passes kept open all year.
  • Close to 50 safety rest areas.

Bridge & structure preservation

Learn how we preserve, inspect and rate the condition of Washington state bridges.

Chip seal

Learn about chip seals (or seal coating, BST, Bituminous Surface Treatment), the application of a special protective wearing surface to an existing pavement.

Performance highlights from the Gray Notebook

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.