A truck driver sits in the driver's seat of a parked semi truck and uses a tablet computer.

Question: How does the hours-of-service (HOS) exception work during adverse driving conditions?

Answer: According to Federal Motor Carrier Safety Administration (FMCSA) 49 CFR Part 395.1(b)(1), the rule allows a driver to have extra time to complete their day after encountering unexpected delays caused by weather or traffic. A driver may extend both driving and on-duty limits by two hours. This is a change from the old rule, which permitted drivers to extend their driving limit, not their on-duty limit. Truck drivers subject to the 14-hour limit will be most affected by the change.


With the expanded hours, more drivers will be eligible to use the exception to wait out unexpected weather or traffic conditions, rather than trying to “race the clock” to complete the run. Drivers will have an added cushion of on-duty time when using the exception. All driving (up to 13 hours for truck drivers) will need to be done within 16 consecutive hours for truck drivers.

Note that the allowable uses of this exception remain relatively narrow. See the definition of Adverse Driving Conditions in §395.2. Motor carriers are obligated to make sure the adverse conditions were unknowable at the time of dispatch. Motor carriers and drivers should check traffic and weather conditions before starting a run. Motor carriers should make sure drivers are aware that they cannot use this exception for routine weather or traffic delays. The delay must be unexpected, and it cannot be due to normal rush-hour traffic, vehicle breakdowns, loading or unloading delays, or the inability to find parking.

Overall, this exception is rare to use. Motor carriers may not qualify to use the adverse driving conditions exception. If the motor carrier feels it has received the violation incorrectly, it has the option to submit a DataQ. However, before submitting the DataQ, consider the following:

  • Did the driver note the exception on the log?
  • Did the driver pass other available parking locations?
  • Was the motoring public warned of the incident before encountering the slowdown?


  • Train operations staff on the HOS exception for adverse conditions.
  • Monitor weather and traffic reports to ensure drivers are aware of adverse conditions.
  • Train drivers how to enter this exception into their electronic logging devices.
  • Develop an internal process for using and documenting the HOS exception for adverse conditions.

As always, you can count on the commercial truck insurance professionals at The Daniel & Henry Company to assist you through challenging claims and all of our insurance, risk management, and safety issues. Contact us today to discuss solutions for your transportation risk management program.

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