U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
Washington Division
FHWA requires inspections of all tunnels carrying traffic on public roads to insure their safety and reliability. This program was initially mandated in the Moving Ahead for Progress in the 21st Century Act (MAP-21). The establishment of the requirements were detailed in the Federal Register in August 2015 defining the National Tunnel Inspection Standards (NTIS).
The NTIS (23 CFR 650, Subpart E) require States to:The data provided below for the State of Washington is based on the National Tunnel Inventory (NTI) data that was submitted into the Federal database in March 2023 and released as of June 15, 2023. In Washington State, there are 63 tunnels carrying public roads that are subject to the Federal inspection requirements. Of those structures, 52 tunnels are State owned, 4 tunnels are owned by local agencies, 1 tunnel is owned by a railroad, and 6 tunnels are owned by the National Park Service (NPS).