A registered vehicle can be recognized by the DOT number displayed on its exterior.
The Federal Motor Carrier Safety Administration (FMCSA) explains: “The USDOT Number serves as a unique identifier when collecting and monitoring a company's safety information acquired during audits, compliance reviews, crash investigations, and inspections.”
The Department of Transportation states that a vehicle must be DOT registered and compliant with these regulations if it is used for interstate commerce and additionally meets one of more of the following conditions.
This can apply to either the gross vehicle weight rating (the maximum operating weight, including load) or gross combination weight rating (for example, the maximum operating weight of a tractor-trailer combination).
Gross weight and gross weight rating are different. The gross vehicle weight refers to the weight (including load) as measured, while gross vehicle weight rating represents the upper limit of what is allowable. Under DOT regulations these two are considered equivalent.
DOT registration is required for any conveyance that has a gross vehicle weight rating or gross combination weight rating, or gross vehicle weight or gross combination weight, of 4,536 kg (10,001 pounds) or more, whichever is greater.
The number of passengers carried and the purpose they are being transported are both used in determining whether the vehicle must be DOT compliant. An automobile such as a bus or van that has a capacity of eight or more, including the driver, is registered with DOT if this is performed “for compensation,” that is, if these are paying passengers.
A vehicle that carries more than 15 persons, including the driver, and is not used to transport passengers for compensation must also be DOT compliant.
DOT registration and compliance are necessary for any vehicle used for carrying hazardous materials, of a type and quantity specified by USDOT. For more complete information on what constitutes a hazardous substance and what measures are necessary for compliance, visit the regulations section of the Federal Motor Carrier Safety Administration website.
Apart from federal regulations, some states require their intrastate commercial motor vehicle registrants to obtain a USDOT Number. Click here for a list from the FMCSA.
For a vehicle used in interstate commerce and conforming to one of more of these as defined under one or more of these conditions, DOT registration and compliance are mandatory. There are currently no exemptions.