Safe Driving of Heavy Vehicles and Sharing the Road
Managing a heavy vehicle's physics
The safe-driving questions test whether you can translate mass into time and space. A loaded heavy combination has much longer stopping distances than a car, and the gap must be measured in seconds, not metres. In good conditions, aim for at least a four-second following gap; increase it in rain, at night, or when carrying a high or shifting load. Brake progressively and avoid sudden steering, which can cause rollover or trailer swing.
Seeing and being seen
Heavy vehicles have large blind spots directly in front, along both sides and behind the trailer. Use your mirrors repeatedly, signal early and check a blind spot before changing lanes. When turning, allow for off-tracking: the rear wheels and trailer cut inside the path of the front wheels, and the rear of the vehicle can swing out. Never overtake a heavy vehicle that is indicating a turn, especially on the left, because a cyclist or car may be in the space the truck needs.
Sharing the road
Give cyclists and pedestrians room. When passing a cyclist, leave at least 1.5 metres at speeds over 50 km/h and at least 1 metre at 50 km/h or less. Heavy vehicles are limited to 90 km/h on the open road, so plan overtakes and let faster traffic pass safely. Secure loads before moving; a shifted load changes stability and can fall onto the road.
Worked example
You are driving a 40-tonne truck-and-trailer at 90 km/h. A car pulls into your four-second gap and slows. Do not close up. Ease off, re-establish the gap, and if the car brakes, brake early and progressively. Your loaded combination may need more than twice the distance of the car to stop; the gap is your safety margin, not an invitation to tailgate.
Traps
Do not assume mirrors show everything. Do not cut back in front of a heavy vehicle after overtaking, because the driver needs stopping space. Do not treat the 90 km/h limit as a target in poor conditions.