Is driving beneath the speed limit illegal?

Slow driving
Slow driving

While many drivers are aware of the dangers of driving too fast, some don’t see the harm in driving too slowly. While you're more than likely to gain the ire of drivers behind you, remember that driving under the speed limit is legally fine, but driving excessively slowly can land you in a bit of hot water.

Driving slowly

According to the NSW Road Rules you cannot drive so abnormally slowly that you cause an obstruction. An example of driving ‘abnormally slowly’ would be if you were travelling at a speed of 20 kilometres per hour on a road with a speed limit of 80 kilometres per hour. As a result, you could be causing an obstruction to other drivers and carries a fine of up to $289.

However, the road rules are full of nuances and there are numerous circumstances in which Road Rule 125 might not be applicable due to the 2b clause. In each of these three example circumstances, for example, it would likely be considered reasonable that the road user is travelling below the posted speed limit:

  • A driver might be driving slowly during heavy rain/snow, or in heavy fog, but this is at the discretion of the driver and what they judge to be a safe speed given the visibility/control constraints, 
  • A heavy vehicle ascending or descending a hill.  It might be travelling well below a posted speed limit, but this is because that is the capability of the vehicle in question, similarly, 
  • A cyclist travelling on any road might be travelling below a posted speed limit, but this is dependent on the capability of the cyclist in question. 

Keeping left

Drivers are to keep to the left on a multi-lane road where the speed limit is over 80 kilometres per hour and are only allowed to drive in the right lane in certain circumstances, such as:

  • Overtaking
  • Turning right
  • Making a U-turn from the centre of the road
  • There is a ‘Left lane must turn left sign’ or left traffic lane arrows apply and the driver is not turning left
  • The driver is required to drive in the right lane if traffic signs require a particular kind of vehicle to drive in the marked lane indicated by the signs.
  • Avoiding an obstruction
  • Traffic in every lane is congested
  • The right lane is a special purpose lane in which the driver is permitted to drive
  • There are only two marked lanes and the left lane is a slow vehicle turn out lane.
  • If a ‘Keep Left Unless Overtaking’ sign is displayed, then you must keep left regardless of the speed limit (unless overtaking).



Tailgating is a definite no-no and the road rules make this clear: “A driver must drive a sufficient distance behind a vehicle travelling in front of the driver so the driver can, if necessary, stop safely to avoid a collision with the vehicle. In NSW, the current penalty for tailgating is a $448 fine by way of an on-the-spot fine or penalty notice and 3 demerit points.

Check available venues and dates

Book your Safer Drivers Course today