Trucking Glossary

Plain definitions of the permit, weight, authority and safety terms drivers and dispatchers run into, each tied to the tool that uses it.

Permits and loads

Overweight load: A load that exceeds legal gross, axle or axle group weight limits and needs an overweight permit.

Federal bridge formula: The formula that sets the maximum weight allowed on any group of axles on the Interstate System, based on the number of axles and the distance between them.
GCWR (Gross Combination Weight Rating): The maximum weight a manufacturer rates a power unit and the trailers it tows for, loaded.
GVWR (Gross Vehicle Weight Rating): The maximum loaded weight a manufacturer rates a single vehicle for, including the vehicle, fuel, passengers and cargo.
National Network: The Interstate and other qualifying highways where states must allow trucks up to the federal minimum size limits.
Tandem axle: Two or more consecutive axles whose centers are more than 40 inches and not more than 96 inches apart, treated as a group for weight limits.

BOC-3: A designation of process agents: a filing that names a legal agent in each state who can accept legal papers on behalf of a motor carrier, broker or freight forwarder.
MC number (operating authority): A docket number FMCSA issues when a for-hire motor carrier, broker or freight forwarder is granted operating authority.
USDOT number: A unique identifier assigned by the Federal Motor Carrier Safety Administration (FMCSA) to a commercial motor carrier, used to track its registration, inspections, crashes and safety record.

CDL (Commercial Driver’s License): A license required to drive a commercial motor vehicle above certain weights or one that carries placarded hazardous materials or many passengers.
DOT physical: A medical exam by a certified medical examiner that a commercial driver must pass to hold a medical examiner’s certificate.
ELD (Electronic Logging Device): A device wired to a truck’s engine that automatically records driving time and location to track hours of service.
Hours of service (HOS): The federal rules that limit how long a commercial driver may drive and be on duty before taking required rest.
National Registry of Certified Medical Examiners: The FMCSA list of medical examiners who are trained and certified to perform DOT physicals for commercial drivers.