Who this is for: CDL drivers, fleet managers, owner-operators
Hazmat Route Restrictions for CMV Drivers
Certain hazardous materials are subject to federal route restrictions and preferred route requirements. Highway route-controlled quantities (HRCQ) of radioactive materials and certain explosives must use designated preferred routes. Tunnel restrictions vary by state and locality. Drivers must know and comply with applicable routing requirements before departure.
Important Notice
Hazmat routing requirements vary by material type, quantity, and jurisdiction. Federal requirements are in 49 CFR Parts 177 and 397. State and local restrictions may be more stringent than federal minimums. Always verify routing requirements before departure.
Federal routing requirements — NRHM preferred routes
Under 49 CFR Part 397, carriers transporting highway route-controlled quantities (HRCQ) of radioactive materials must use FMCSA-designated preferred routes, which are selected by states and localities to reduce risk. Carriers must also use preferred routes for certain quantities of explosive materials. Before transporting these materials, carriers must obtain a written route plan and ensure the driver has a copy. FMCSA maintains a routing registry accessible through PHMSA.
Tunnel restrictions
Many tunnels restrict or prohibit the passage of vehicles carrying certain hazardous materials. Tunnel restrictions are set by state and local authorities and vary by location. Common restrictions include prohibiting vehicles carrying flammable compressed gases, explosives, and certain toxic materials from entering tunnels. Drivers must be aware of tunnel restrictions on their route before departure. GPS systems may not always reflect current hazmat routing restrictions — carriers should verify restrictions through state DOT or local authority resources.
Urban area and bridge restrictions
Some urban areas and bridges have additional restrictions on hazmat transport beyond federal minimums. These may be enacted by local governments. Carriers operating in or through metropolitan areas should verify local hazmat routing requirements. Failure to follow local restrictions, in addition to federal requirements, may result in enforcement action.
Carrier routing responsibility
Under 49 CFR 397.67, carriers and their drivers are responsible for selecting routes that comply with all applicable federal, state, and local hazmat routing requirements. Before each trip carrying regulated quantities of hazmat, the carrier should: identify the materials being transported and their hazard class; determine if any federal preferred-route requirements apply; check for tunnel and urban restrictions along the planned route; and document the approved route in the trip records.
Parking restrictions for hazmat vehicles
49 CFR 397.7 and 397.9 restrict where hazmat vehicles may be parked. Vehicles carrying certain high-hazard materials (particularly explosives and radioactive materials) may not be parked in certain locations — near populated areas, schools, or within specified distances of open fires. All hazmat vehicles must not be left unattended on a public street or highway unless the driver is in the cab or the vehicle is in a safe haven. Requirements vary by material type.
Pre-trip route planning for hazmat loads
Route planning for hazmat loads is not something to finalize at the truck stop. Before departure, the carrier or dispatcher should identify: what materials are being transported and their hazard class and UN number; whether NRHM preferred routes apply; any tunnel restrictions on the planned route; and whether overnight stops will be required and where the vehicle can legally park. Document the approved route in the trip records — this creates a record that the carrier took its routing obligation seriously. GPS navigation that isn't hazmat-aware may route through restricted tunnels or urban areas that prohibit certain hazard classes. Verify the route independently, not just through the device on the dash.
Frequently Asked Questions
Do ordinary fuel trucks or propane delivery vehicles have routing requirements?
Vehicles transporting flammable liquids or gases in quantities that require placarding are subject to general hazmat regulations, but may not be subject to the NRHM preferred route requirements (which apply primarily to HRCQ radioactive materials and certain explosives). However, tunnel restrictions and local routing requirements may still apply.
Where can a carrier find routing requirements for a specific state?
State DOT websites often publish hazmat routing information. PHMSA's website provides resources for hazmat routing. Some states use the FMCSA's Hazmat Route Registry. For complex routes or high-hazard materials, consult a hazmat compliance professional or the state DOT directly.
How can a driver identify tunnel restrictions on their specific route before departing?
Check the tunnel authority's website directly (such as the Port Authority for NY/NJ tunnels) and the applicable state DOT hazmat routing page. PHMSA also maintains a hazmat route registry searchable at phmsa.dot.gov. Call the tunnel authority directly if the online information is ambiguous — restrictions vary by hazard class and some tunnels prohibit certain materials during specific hours or weather conditions.
GPS navigation shows a route through a tunnel but doesn't flag a hazmat restriction — is the route still compliant?
Not necessarily. Standard GPS devices and consumer navigation apps do not reliably reflect hazmat routing restrictions. Under 49 CFR 397.67, compliance is the carrier's responsibility regardless of what the GPS suggests. Before any hazmat trip through a metropolitan area or known tunnel corridor, verify restrictions independently through state DOT or tunnel authority resources. GPS failure to flag a restriction is not a defense at enforcement.