Washington Truck Bans & Hazmat Routes

Where Washington keeps trucks out

No cars-only parkways here. Your real chokepoint is Seattle's SR 99 tunnel, where placarded hazmat is banned outright, so flammables and propane take a surface detour (WSDOT tunnel rules; hazmat routing under 49 CFR 397). Seattle also maps major truck streets and posts weight and clearance limits. Run a truck GPS profile. A car nav points you at a low city underpass or into the tunnel.

Key restrictions

• SR 99 tunnel (Seattle): placarded hazmat prohibited, no exceptions
• Run Seattle's designated major truck streets; obey posted weight and clearance plates
• Use a truck routing profile; a car GPS misses low city underpasses and the tunnel ban

• Parkway / road ban: No cars-only or commercial-registration parkway bans. Seattle uses a designated major-truck-street network and posted weight/clearance limits instead.
• Hazmat: Seattle's SR 99 tunnel prohibits placarded hazardous materials outright, so flammable and propane loads must take a surface route. WSDOT posts and enforces the ban. Elsewhere, placarded hazmat follows state-designated routes under 49 CFR 397, enforced by the Washington State Patrol.
• Through-truck routes: Seattle designates a major-truck-street network and posts no-truck and weight-limited local streets; a local delivery may leave the network by the most direct path to its stop. Statewide, STAA National Network access applies (Seattle SDOT; RCW 46.44).
• Fine: Driving placarded hazmat into the SR 99 tunnel or ignoring a posted truck restriction is a traffic infraction, with base fines commonly a few hundred dollars; a hazmat routing violation can also draw an out-of-service order and federal penalties. Confirm the current amount with WSP or the citing court.

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