What is hours of service?
Also called HOS
Hours of service are the legal limits on how long a commercial driver may drive and work before taking mandated rest. They cap daily driving, total on-duty time and weekly hours.
The limits govern driving time within a shift, the total on-duty window that driving must happen inside, required breaks, and a rolling weekly ceiling that resets after enough consecutive time off.
Compliance is recorded electronically rather than on paper, so the clock is visible and not negotiable.
What it means on a dispatch desk
A driver's remaining hours are a hard constraint, not a target to optimise toward, and the schedule has to be built from them rather than around them. The most common dispatching failure is booking an appointment the clock cannot legally reach and discovering it when the driver is already committed. Check remaining hours before accepting, every time, and treat a facility's known dwell as hours already spent.
Related terms
- Dwell timeDwell time is how long a truck, trailer or container sits idle at a facility waiting to be handled. It is the underlying measure that detention charges are calculated from.
- LayoverA layover is an overnight delay where a driver has to wait until the next day to load or unload, and is paid a flat daily rate for it rather than an hourly detention rate.
- DetentionDetention is money owed to a carrier when a shipper or receiver holds the truck beyond the free time agreed for loading or unloading, usually two hours. It is billed by the hour after that window closes.
- LaneA lane is a regular origin-to-destination pairing that a carrier runs repeatedly, such as Dallas to Atlanta. Rates, volumes and seasonality are all discussed per lane.
- Out of serviceAn out-of-service order stops a driver or a vehicle from operating until the problem that caused it is corrected. It is issued at the roadside during an inspection, or against an entire company for serious regulatory failures.
Knowing the term is the easy half
Knowing which carriers are worth calling this morning is the hard half.
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