Hours of Service
Federal regulations (49 CFR Part 395) that limit the number of hours a commercial motor vehicle driver can operate within a day and week, enforced through electronic logging devices to prevent fatigued driving.
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Compare ELD Compliance software →The Core HOS Limits in Plain Numbers
Exemptions That Change the Math
Not all drivers operate under the standard property-carrier rules. The 100 Air-Mile Radius Exemption (also called the short-haul exemption) allows drivers who stay within 100 air miles of their work reporting location, return to that location each shift, and do not exceed 11 driving hours to use a time record instead of a full ELD log — as long as the carrier retains those time records for 6 months. The Adverse Driving Conditions exemption allows drivers to extend the driving window by up to 2 hours when unexpected conditions (ice, flooding, accidents) make it impossible to safely complete the planned trip. The Agricultural Exemption suspends HOS rules for drivers transporting agricultural commodities within 150 air miles of the source during planting and harvest seasons. Carriers relying on these exemptions must document them carefully — misapplied exemptions are treated as logbook falsification.
Operational Scenario: The 14-Hour Trap
How a delayed pickup burns the clock on compliant drivers
A driver for a Midwest LTL operation logs on at 6:00 AM. A shipper delay holds the truck at the dock until 10:30 AM — four and a half hours of on-duty not-driving time. The driver departs, drives 8 hours, and arrives at the destination at 6:30 PM. With the 30-minute mandatory break taken at the 8-hour mark, the driver has used 12.5 hours of the 14-hour window. They cannot legally begin the return leg even though they have 8.5 hours of remaining driving time, because the 14-hour window closes at 8:00 PM and the return leg would push them past it. This is the 14-hour trap: dock delays burn the on-duty clock even when the wheels aren't turning, shrinking the usable driving window without reducing fatigue. Dispatch teams that don't account for average loading times when building schedules routinely put drivers in this position.
HOS Violations and Their CSA Severity Weights
What Fleet Managers Should Build Into Dispatch Workflows
- Build dock dwell time into route plans — assume 45–90 minutes of on-duty not-driving time per stop and schedule departure windows accordingly
- Set ELD alerts for drivers approaching 10 hours of driving so they have time to reach a safe parking location before the 11-hour limit triggers
- Configure 14-hour window alerts at the 12-hour mark — by hour 12, dispatch needs to know whether the driver will make their delivery before the window closes
- Document adverse driving condition extensions in the driver's log at the time of use — adding a note after the fact creates falsification exposure
- For short-haul operations using the 100 air-mile exemption, confirm drivers are returning to their home terminal each day before removing them from ELD requirements
- Run a weekly HOS exception report from your ELD platform — most ELDs surface hours violations 24–72 hours after they occur, not in real time
- Train drivers on the sleeper berth split provision — many drivers leave hours on the table because they don't know how to legally split their rest