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.

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

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

1,557 work zone-related crashes

were recorded on state highways in 2025.

542 people were injured

in 2025 due to work zone-related crashes. 

29% increase in fatality collisions

in work zones from 2024 to 2025.