Hours of service

Hours of Service (HOS) regulations are issued by the Federal Motor Carrier Safety Administration (FMCSA) and govern the working hours of anyone operating a commercial motor vehicle (CMV) in the United States. These regulations apply to truck drivers, commercial and city bus drivers, and school bus drivers who operate CMVs. These rules limit the number of daily and weekly hours spent driving and working, and regulate the minimum amount of time drivers must spend resting between driving shifts. For intrastate commerce, the respective state's regulations apply.

The FMCSA is a division of the United States Department of Transportation (DOT), which is generally responsible for enforcement of FMCSA regulations. The driver of a CMV is required to keep a record of working hours using a log book, outlining the total number of hours spent driving and resting, as well as the time at which the change of duty status occurred. In lieu of a log book, a motor carrier may keep track of a driver's hours using an electronic on-board recorder (EOBR), which automatically records the amount of time spent driving the vehicle.