Vehicles measuring 7.5m or more display a sign reading ‘Do not overtake turning vehicle’ – you know, those red and yellow ones you might have noticed on the back of long trucks or buses.

According to the law, you must not overtake a vehicle displaying a ‘Do not overtake turning vehicle’ sign if it’s signalling, and in the process of turning. Here’s why.

Trucks need space

You’ve probably noticed occasionally that a long vehicle will take up more than one lane when turning. This is perfectly legal, because sometimes they need more space to turn at corners, intersections and roundabouts due to their length.  In fact, a heavy or long vehicle displaying a ‘Do not overtake turning vehicle’ sign is allowed to use either or both lanes to turn left or right. It must be safe to complete the manoeuvre and the vehicle needs to be within 50m of an intersection.

Attempting to overtake a truck, bus or other long vehicle when it’s completing this manoeuvre could put you in danger of colliding with the much larger vehicle.

It may also be an expensive overtaking move. Passing or overtaking a turning vehicle displaying a ‘do not overtake turning vehicle’ sign may cost you $242, a $99 Victims of Crime Levy and two demerit points.

Roundabout roulette

Watch out for large vehicles when you’re navigating a multi-lane roundabout. Some long vehicles will need to stay in the left lane of a roundabout even though they’re making a right turn because they may encroach into the adjacent lane due to their size.

RAA Senior Manager Safety and Infrastructure Charles Mountain says motorists make the common mistake of attempting to overtake a long vehicle exiting a roundabout to the right.

“If a truck needs to cross into the right lane as they turn, and you’re in the lane next to it, you could collide,” he says.

Overtaking on the left

There are only a select few occasions when you can pass a vehicle on the left. For example, when the vehicle is turning right into a side street. However, it can be a particularly risky manoeuvre when a truck is turning.

As we mentioned earlier, trucks can turn left from the right lane, so ducking down the left lane could end in a collision with a much larger vehicle. Instead, only overtake on the right and be alert for turning trucks.