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What’s the road rule regarding speed limits? If I am driving in an 80kmh speed zone, am I required to travel at 80kmh? If I am driving in an unfamiliar area or looking for an address, can I safely drive five or 10kmh under the speed limit?
W. Glennie, Clunes
A speed limit is a maximum that a driver may travel at. The conditions of the road, weather or other factors may mean a driver should travel at a lower speed than the posted speed limit.
The rules about driving below the speed limit relate to not obstructing other road users rather than stating a minimum speed.
A driver must not unreasonably obstruct the path of another driver or pedestrian. A driver is not considered to be unreasonably obstructing another road user if the driver is stopped in traffic; or if the driver is driving more slowly than the other vehicles (unless the driver is driving abnormally slow in the circumstances).
The rules provide an example of a driver driving abnormally slow: “A driver driving at a speed of 20 kilometres per hour on a length of road to which a speed limit of 80 kilometres per hour applies when there is no reason for the driver to drive at that speed on the length of road”.
The key factor in this example is “when there is no reason” for the slower speed. Under adverse conditions, such as rain, at night, a poor road surface, or in areas with high pedestrian activity, it is often necessary to drive at a speed that is lower than the posted speed limit.