Hours of Service (HOS)

Federal regulations limiting the driving and on-duty time for commercial motor vehicle (CMV) operators to prevent driver fatigue.

Hours of Service (HOS) are rules issued by the Federal Motor Carrier Safety Administration (FMCSA) that govern the working hours of anyone operating a commercial motor vehicle (CMV) in the United States. The primary purpose of HOS regulations is to reduce accidents caused by driver fatigue. For property-carrying drivers, key provisions include the 14-hour driving window, which limits driving to a 14-consecutive-hour period after coming on duty, and the 11-hour driving limit, which caps actual driving time at 11 hours within that 14-hour window. Additionally, drivers must take a 30-minute break after 8 cumulative hours of driving. The rules also include a weekly limit: drivers cannot drive after accumulating 60 on-duty hours in 7 consecutive days or 70 on-duty hours in 8 consecutive days. A driver may restart their 60/70-hour clock after taking at least 34 consecutive hours off duty. Adherence to these regulations is critical for legal operation, as violations are tracked via ELDs and negatively impact a carrier's CSA score.

Example

A truck driver starts their on-duty clock at 6:00 AM. According to the 14-hour rule, they are prohibited from driving their CMV after 8:00 PM that day, regardless of how much time they spent actually driving.