Sharing the Road Safely With Heavy Vehicles

Large, heavy trucks – such as Australia’s famous roadtrains - are a common sight on outback roads.  They move huge amounts of the country’s freight safely and efficiently.  Sharing the road with these large vehicles requires courtesy, patience and good driving behaviour from everyone involved.


Safe Overtaking

It is always better to stay behind a slower vehicle than to take an unnecessary risk. You’ll need at least one and a half kilometres to safely overtake a truck travelling at 100km/h.  Probably more if you’re unfamiliar with the road.

Remember these simple steps to help you overtake safely:

  • Leave a gap between yourself and the vehicle you are trying to overtake. This gives you more time to build up speed to complete your overtaking, and gives you a much better view of the road ahead.
  • Check you have plenty of clear road ahead to overtake safely. 
  • If you can, drop down a gear before starting to overtake.  You’ll need the extra power.
  • Watch your speed - penalties for speeding still apply when overtaking.
  • Once you are completely clear of the overtaken vehicle, safely re-join your lane as soon as you can.
Sharing the Road Safely

Western Australia’s roads are also used to transport some of the world’s largest and heaviest loads, often to remote parts of the State.  We call them OSOM loads – short for ‘Oversize Overmass’.

The routes used by these loads – some stretching thousands of kilometres - are also among the longest in the world.  Their size means they have to travel much slower than normal traffic, sometimes taking a number of days to reach their remote destinations.

Image: pic 1 OSOM load.RCN-D13^23716520.JPG 

A typical OSOM load on the move

If you travel by road in outback WA, chances are sooner or later you’ll encounter one of these large, slow-moving loads, sometimes travelling in convoy.  You will need to know how to share the road safely with them.

Image: pic 2 Escort.RCN-D13^23716521.JPG  Image: pic 3 Pilot.RCN-D13^23716525.JPG

Traffic Escort Vehicle

Pilot Vehicle​

A Traffic Escort vehicle (left) and Pilot Vehicle (right) - if you see either on the road, be prepared to stop and obey the Pilot or Traffic Escort Officer's instructions.  

OSOM loads are usually accompanied by one or more Pilot vehicles and the largest OSOM loads are also accompanied by a Traffic Escort vehicle.  Their job is to warn other road users of the presence of large, slow-moving loads.  Pilot vehicles are identified by their orange flashing lights and warning signage on the roof of the vehicle, and Traffic Escort vehicles are easily identified by their distinctive flashing red white and blue roof-mounted lights and warning signage.  If you see a Pilot or Traffic Escort vehicle, you must prepare to:

  • Reduce speed.
  • If the OSOM load is coming towards you, move as far as possible to the left and be prepared to stop completely.
  • Obey all instructions given by the Traffic Escort or Pilot.  Your safety, and that of the load they are accompanying, are their priorities.
Safety Postcards

Main Roads WA has produced a set of downloadable postcards, designed by Perth artist Hayley Welsh, which show a variety of heavy vehicles and carry useful advice for motorists.

With informative ‘Trip Tips’ on the reverse, the postcards are available free from roadhouses, Tourist Information Centres and other roadside locations throughout WA, or you can download them here:

Useful Links

Find out more about sharing the road safely with heavy vehicles on the following websites:



Modified: 05 Apr 2017