Adverse driving conditions

Scope

This regulation applies to drivers operating property-carrying or passenger-carrying commercial motor vehicles (CMVs) in interstate commerce who encounter adverse driving conditions.

Regulatory citations

• 49 CFR 395.1(b)(1) — Adverse driving conditions

Key definitions

• Adverse driving conditions: Snow, ice, sleet, fog, or other adverse weather conditions or unusual road or traffic conditions that were not known, or could not reasonably be known to a:
  • Driver immediately prior to beginning the duty day,
  • Driver immediately before beginning driving after a qualifying rest break or sleeper berth period, or
  • Motor carrier immediately prior to dispatching the driver.
  Adverse driving conditions do not include:
  • Rush-hour traffic,
  • Anticipated/expected bad weather,
  • Loading/unloading delays, or
  • Conditions that were apparent before the run was dispatched.

• Commercial motor vehicle (CMV): A self-propelled or towed motor vehicle used on a highway, in interstate commerce, that meets any one of the following criteria:
  • Has a gross vehicle weight rating (GVWR) or gross combination weight rating (GCWR), or gross vehicle weight (GVW) or gross combination weight (GCW), of 10,001 pounds or more, whichever is greater;
  • Is designed or used to transport more than 8 passengers (including the driver) for compensation; or
  • Is designed or used to transport more than 15 passengers (including the driver), and not used to transport passengers for compensation; or
  • Is transporting hazardous materials of a type or quantity which requires placarding.

Summary of requirements

Property-carrying CMVs: Drivers of property-carrying CMVs who encounter adverse driving conditions and cannot safely complete the run within the 11-hour driving time limit or 14-hour duty window may increase their driving time and duty window by up 2 hours to make up the time that was lost.

When using this exception, the driver of a property-carrying CMV may not drive:

• For more than 13 hours following 10 consecutive hours off duty, or
• After the end of the 16th consecutive hour since coming on duty following 10 consecutive hours off duty.

Passenger-carrying CMVs: Drivers of passenger-carrying CMVs who encounter adverse driving conditions and cannot safely complete the run within the maximum 10 hours of driving or 15 hours of on-duty time may increase their driving and on-duty time by up to 2 hours to make up the time that was lost.

When using this exception, the driver of a passenger-carrying CMV may not drive:

• For more than 12 hours following 8 consecutive hours off duty, or
• After 17 hours of on-duty time following 8 consecutive hours off duty.

Drivers in Alaska. A CMV driver in Alaska who encounter adverse driving conditions may drive for the length of time needed to complete the run. After the run is completed, the driver must be off duty for:

• 10 consecutive hours if operating a property-carrying CMV, or
• 8 consecutive hours if operating a passenger-carrying CMV.