Speed Limits, Stopping Distances and Vehicle Control
Default limits and posted limits
In Tasmania, the default speed limit in built-up areas is 50 km/h unless signs say otherwise. Rural roads default to 100 km/h unless signed lower. School zones are typically 40 km/h during posted times. Always drive to conditions: the limit is a maximum, not a target. In rain, fog, at night, or on gravel, reduce speed well below the limit.
Stopping distance
Total stopping distance is reaction distance plus braking distance. Reaction distance grows with speed and with fatigue or distraction. Braking distance grows with the square of speed, so doubling speed roughly quadruples braking distance. Wet roads can double braking distance again. A simple rule of thumb is a two-second gap in ideal conditions, but exam questions usually expect at least three seconds, and more in poor conditions.
Vehicle control
Keep both hands on the wheel, use smooth steering and braking, and look where you want to go. In a skid, ease off the accelerator and steer gently in the direction you want the front of the car to go; do not brake hard. Maintain tyre pressure and tread, and check lights and brakes regularly. Loads must be secured.
Common traps
- Treating the posted limit as safe in all conditions.
- Underestimating how much wet roads increase stopping distance.
- Braking hard during a skid.
- Forgetting that school zone times are posted and enforced.
Worked example
Travelling at 60 km/h, your total stopping distance on a dry road is roughly 45 metres. On a wet road it may exceed 60 metres, so drop your speed and increase your gap.
Rule of thumb
Speed sets your stopping distance; conditions decide whether that distance is safe.