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Hazardous Materials Routing

MDOT conducted a study to better understand and evaluate the risks associated with transportation of hazardous materials on the Ambassador Bridge from Porter Street to Canada should any of the existing restrictions be changed. The following information addresses some of the commonly asked questions about hazardous materials routing.

Learn more about Hazardous Materials Routing

  • MDOT is the authorized agency in Michigan responsible for ensuring NRHM routing designations, restrictions and requirements comply with federal routing standards and state law. This authorization includes a request to consider a change to existing NRHM routes.

  • Only transportation system infrastructure owners in the state of Michigan can request a change to the existing routes.

  • MDOT received a formal request from the Detroit International Bridge Co., owners of the Ambassador Bridge in Detroit, to modify the current restrictions.

  • Many safety considerations are evaluated, including but not limited to:

    • Transportation infrastructure, such as the physical width, height, elevation of the actual road or bridge, and the nearby terrain.
    • Emergency response capabilities, delays in transportation, congestions, and crash history.
    • Assessment of exposure, such as population density or special populations, types, and quantities of NRHM, and impacts upon commerce.
    • Through highway routing, which must ensure continuity of movement to enhance public safety.
  • MDOT will issue a final determination no later than May 17, 2025, which is 18 months after the study, A Hazardous Material Route Registry Study and Report for the Ambassador Bridge in Detroit, MI, was   made available for public review and comment. 

  • Different agencies have different roles when providing emergency response to a spill or release. Transportation and environmental response agencies, such as U.S. Coast Guard, U.S. Environmental Protection Agency (EPA), and the Michigan Department of Environment, Great Lakes, and Energy (EGLE), report adequate response capabilities but also systematically look for reduction in risk. The Coast Guard publishes its ability to respond to incidents in all their districts, including the Ninth District, Sector Detroit. Local-level response capabilities may vary by specific location, but state and federal response would likely remain the same regardless of where a spill might occur.

  • Exposure and other risk factors were analyzed in the synopsis report. The distance to sensitive areas (such as homes, schools and water sources) was also considered, based upon information gathered from public comments. The risk of exposure from an incident at a specific point could be increased due to an elevated level of transporting certain materials without secondary containment. The risk of a spill occurring in the Detroit River would likely not change as the material will be traversing the waterway at some point regardless.

  • Hazardous chemicals are characterized by their flammability, corrosivity, reactivity, or toxicity. Some chemicals may exhibit one or more of these characteristics at the same time. The effect could vary based on the characteristics of the chemical.

  • Their role is to provide technical support to incident command during an event, as well as mitigation and recovery efforts after the initial incident.

  • The FMCSA was established as a separate administration within the U.S. Department of Transportation on Jan. 1, 2000, pursuant to the Motor Carrier Safety Improvement Act of 1999. Among other things, the FMCSA enforces hazardous materials regulations, which are designed to ensure the safe and secure transportation of hazardous materials.

    These rules address the classification of hazardous materials, proper packaging, employee training, hazard communication, and operational requirements. The FMCSA will then make this information available through publication in the Federal Register.

  • The Michigan State Police (MSP), including the MSP Commercial Vehicle Enforcement Division, and/or local police authorities.

  • MDOT is the authorized agency in Michigan responsible for NRHM routing designations, restrictions and requirements, and therefore makes the final decision on the recommended changes.

  • Public comments may be submitted using the online comment form, visiting the project webpage, by mail or e-mail to Monica Monsma at The public comment period is open from Nov. 15 until Dec. 23, 2023. MDOT will review all comments.

    Comments may be mailed to: 

    Monica Monsma
    MDOT Environmental Services Section
    425 West Ottawa St. 
    P.O. Box 30050 
    Lansing, MI 48909