Transportation of hazardous materials by road, rail, sea, air or pipeline may have unique risks associated with choices of transport method, route, containers or vessels, quantities transported and many other factors. Impacts of accidents may vary greatly depending on the nature and location of the accident.

In addition to traffic accidents, other types of accidents may occur, particularly during loading or unloading. Failure of valves or other equipment can also result in releases of materials.

Transportation risk assessments are often utilized as part of a risk management process. These assessments are useful in selecting the most appropriate methods, routes and equipment for transporting hazardous materials, reducing risks, aiding in emergency planning, addressing concerns of the public or others, and aiding in seeking regulatory approvals.