In any 72 hour period (three days) there must be a total of at least 27 hours of non-work time including three breaks of at least seven continuous hours. The remaining non-work time can be made up of other continuous breaks of 30 minutes or more. This non-work time cannot include breaks from driving of less than 30 minutes as they are counted in work time.
The example provided on page 13 of the Code of practice - Fatigue management of commercial vehicle drivers helps to explain how these requirements work in practice.
For practical purposes, to determine whether a driver has met the requirement for three breaks of at least seven continuous hours in any 72 hour period, the 72 hours is counted from the end of a long break of seven continuous hours or more.
In well managed circumstances, a solo driver can work for up to 17 hours, but there must be a break of at least seven continuous hours immediately before and after the 17 hour period. These breaks of seven continuous hours would be included in the 27 hours of non-work time referred to above. The 17 hours will include breaks from driving of 20 minutes for every five hours, which would add up to at least one hour of breaks from driving.
It is important to remember that the limits on the number of hours that can be worked in a 14 or 28 day period mean it is not possible to continuously work 17 hour days.
Solo drivers can work through the night, but it is recommended that night work be kept to a minimum to guard against the risk of fatigue.
Solo drivers who do continuous rotating shift work for five or more days in a row, should, as far as practicable, have at least 24 continuous hours of non-work time between shift changes (for example, going from day shift to night shift).
