Any weather conditions (snow, sleet, fog, etc.) or unusual road conditions that a driver were not aware of or were not known before starting the trip, immediately before the driver began driving from their last place of rest, are known as adverse driving conditions.
If the driver knew that there were going to be adverse driving conditions it cannot be claimed as such and the driver must comply with the regular daily limit.
This does not include delays at border crossings.
Canada - South of Latitude 60°N
If a driver encounters adverse driving conditions during a trip south of latitude 60°N (that the driver can usually complete under normal conditions), the driver can make the following adjustments:
- Increase the driving and on-duty time in the cycle by up to 2 hours.
- Decrease daily off-duty time by up to 2 hours. For example, if the driver drives for 15 hours (i.e., 13 hour limit + 2 hour extension), the driver takes 8 hours off-duty (i.e., 10 hours – 2 hours). The driver must take the required 8 consecutive hours of core off-duty time.
Therefore, with this exemption, the driver can extend the daily driving and on-duty limits, as well as the work shift driving and on-duty limits. However, despite the exemption, a driver must stop driving after 16 hours of elapsed time in a work shift.
Canada - North of Latitude 60°N
If a driver encounters adverse road conditions during a trip north of latitude 60°N (that the driver can complete under normal conditions), the driver can make the following adjustments:
- Increase driving time by up to 2 hours.
- Driver must take the required 8 consecutive hours of off-duty time.
Ref: Alberta Motor Transport Association, Alberta Reference Guide for Hours of Service Training Development, June 23, 2008.