Preventing and dealing with truck fires

Directly or indirectly, we’re all paying for the damage caused by heavy vehicle fires – in non-delivery of goods; in higher insurance premiums that trigger higher freight rates; through costly traffic delays; and via tax-funded repairs to infrastructure.

Much more difficult to evaluate is the cost to the health system of trauma experienced by truck drivers, their families, other road users and first responders.

NTI Insurance is the major heavy vehicle insurer in Australia and the company's 2020 report stated that more than 10 per cent of major vehicle losses were due to fire. Of those incidents, 32 per cent were in the engine bay and truck cabin areas. Significantly, more than half of those fires were caused by electrical system failures and the remainder were mainly caused by wheel and tyre issues.

In 2019, the National Heavy Vehicle Regulator awarded the then Australian Road Transport Association – now the ARTSA Institute (ARTSA-i) – and the National Bulk Tanker Association (NBTA) a Heavy Vehicle Safety Initiative Round 4 Grant to investigate truck fire prevention strategies.

In undertaking this work, ARTSA-i and the NBTA enlisted the technical expertise of the Truck Industry Council (TIC).

The experts compiled a list of the most common causes of truck fires.

Some of the more common causes of fires in trucks include:

• Arcs at the starter motor or in battery cables, mainly due to poor electrical installation and poor design practices, with alternator cables or positive-feed wires into the cabin causing sparks. Heavily loaded circuits overheat terminals, causing insulation to burn.

• Other heat creators are aftermarket fuse holders and minor electrical components.

• Fuel-line abrasions or failures can result in leaks or sprays of fuel onto the exhaust, or the location of lubrication and hydraulic oil lines too close to the exhaust system can cause pipe rupture. Engine head and block operating temperatures aren’t high enough to ignite hydrocarbon liquids, but fuel and oil are easily ignited by exhaust pipe and turbocharger temperatures.

• Turbocharger failures cause excessive temperatures in the air intake. Typically, the turbo centre bearing fails, causing a lubricating oil fire to start and spread towards the boost side, where the fire burns through the boost-side tubes or elbows.

• Flammable material, often vegetation, collects beside the turbocharger or the exhaust system. Modern exhaust systems with DPFs are very hot.

• Tyres catch fire because they are flat or poorly inflated, or they are rubbing on hard mudguard surfaces. Overheated tyres can catch fire after a vehicle stops.

The ARTSA-i report also provides some hints on how to avoid serious truck fires. It points out that engine compartment fires, where a fuel leak, engine failure or a turbocharger malfunction occurs, often result in a minor explosion that can be heard.

Performance issues leading up to a fire-causing failure may also occur and should be reported. For example, a fuel leak can result in rough running and under-fuelling the engine because fuel is escaping elsewhere. Electrical fires are often considered silent, because they don’t create any noise before the fire has started, but a clue could be sudden electrical disturbance noise in the radio.

Trailing equipment was found to cause fewer electrical-fire incidents, mainly because of their much lower-powered electrical circuits. Trailer fires were found to be caused mainly by wheel-related issues.

Wheel bearing failure results in bearing grease catching fire. Wheel bearing failure also occurs on trucks, but less commonly.

‘Dragging’ brakes are often caused by damage to the pneumatic spring-brake system. If there’s insufficient air supply and pressure to restrain the springs, the shoes or pads will ‘drag’. If a brake friction surface becomes red hot, a fire at the tyre rim can result.

Tyres also catch fire because they are under-inflated or rubbing on hard mudguard surfaces.

A surprising cause of some trailer fires is friction at mezzanine support brackets, generating hot filings that can ignite flammable freight.

In case of fire

The ARTSA-i report includes the procedure a driver should follow, in the event of a fire:

• Assess the situation, making sure you and others around you are safe.

• Shut down the vehicle and disconnect the batteries, if possible, using the isolation switch fitted to Dangerous Goods Vehicles.

• If practical and safe to do so, attempt to fight the fire. If using a fire extinguisher, it should be used with controlled release, with short movements from the bottom of the fire to the top, while avoiding breathing in the fumes.

• If practical and safe to do so, uncouple the prime mover, to separate it from the trailer(s).

• Call 000.

• Call your office, explain the situation and start the reporting process.

A driver should not rely on memory of the incident, because an investigation can take several months or even years to conduct. A driver may not be contacted for a long period of time and investigators rarely inspect the burnt vehicle at the scene. Therefore, drivers should record all their observations.

Related reading:
The importance of clean air
How to reverse a B-double
The real cost of mismatched tyres

As most phones are equipped with cameras, photos should be taken as soon as practical, after all fire-fighting efforts have finished and authorities have been notified.

A driver should record observations from the pre-trip inspection and note any abnormal smells, noises, vibrations or visual observations prior to and during the fire. Each observation should be recorded against an approximate time of day or night, so that a chronological order of events can be established.

In July 2022, the Preventing Fires-Truck Inspection Manual was published on-line by the NSW Environment Protection Authority (EPA). Its aim is to give truck drivers the inspection skills to identify and correct faults that have the potential to cause heavy vehicle fires.

The manual shows truck operators how to inspect their vehicles and identify problems before they result in a fire. It also helps drivers identify faults, such as overheating brakes and electrical troubles, while in transit and what to do if a problem develops on the open road.

The manual and checklist can be downloaded here.