Stability safety technologies
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Preventing heavy vehicle loss of control and rollover crashes
Every road crash fatality in Queensland costs an estimated $2.7 million. Every hospitalisation costs an estimated $239,000.
Twenty per cent of road fatalities in Queensland involve heavy vehicles. Around 30 per cent of those are related to a loss of control or rollover.
The Department of Transport and Main Roads is continually searching for methods to reduce the road toll. For this reason, we investigated new and emerging heavy vehicle stability systems that offer potential to prevent, or reduce the severity of, loss of control and rollover crashes.
Our recommendation for stability systems
When purchasing new vehicles, we recommend you:
- choose electronic stability control (ESC) for prime movers
- choose roll stability control (RSC) for trailers and semi-trailers
- consider electronic stability control (ESC) for rigid trucks depending upon whether their configuration or freight task makes them more likely to crash.
Below is a summary of our findings. We encourage you to read the full report.
When heavy vehicle stability systems can help you avoid a crash
Heavy vehicle stability systems detect when a vehicle is approaching its handling limits. They then apply the brakes on individual wheels or axles to help the driver maintain control.
ESC and RSC are claimed to be highly effective in potentially dangerous situations like:
- overestimating curve speed limits (for example, narrowing curves, highway exits)
- obstacle avoidance manoeuvres with sudden steering input (for example, steering from the shoulder back onto the road and skidding)
- laden semi-trailer in narrow curves on slippery surface (jack-knifing on turns).
The economic benefits of heavy vehicle stability systems
We analysed 440 Australian crashes to find out if heavy vehicle stability systems are cost-effective.
Not only are heavy vehicle stability systems effective in reducing the road toll, they are economical investments for prime movers, and particularly for trailers and semi-trailers.
Benefits are measured in lives, injuries and money saved by preventing or reducing the severity of some rollover and loss of control crashes.
Systems for prime movers
Our analysis shows you will see the greatest economic benefit for articulated vehicles if you use a combination of ESC (prime mover) and RSC (trailer) systems.
We calculated a benefit-cost ratio of 1.43 for combined systems.
This means, when spending money on stability systems for prime movers and trailers, the total benefits are predicted to outweigh total costs by a factor of 1.43 to 1.
Systems for trailers
Simply equipping trailers with RSC is even more cost effective than fitting ESC to prime movers.
Analysis shows the total benefits are predicted to outweigh total costs by a factor of 2.38.
Trailer-only stability systems achieved the highest benefits for a given cost because:
- trailer-only systems are cheaper than prime mover systems
- articulated vehicles are more likely to be involved in a rollover crash than heavy rigid vehicles.
Systems for heavy rigid vehicles
Our research showed that while heavy vehicle stability systems are effective in articulated vehicles, they are less effective in heavy rigid vehicles.
However, our investigation did not identify if particular heavy rigid vehicles might benefit more than others, for example a truck and dog trailer. Likely reductions in the cost of these systems over the next few years will make them more favourable across the whole fleet.
The limitations of heavy vehicle stability systems
No technology can defy the laws of physics. Heavy vehicle stability systems are limited by how well the tyres grip the road.
The following crash types will still occur despite heavy vehicle stability systems:
- Rollover crashes where the vehicle enters a curve so fast it cannot be slowed sufficiently to prevent a rollover.
- Fatigue-related crashes or similar where the driver simply does not perceive a curve and drives straight ahead.
- Crashes where the vehicle is tripped, causing a rollover.
Buying heavy vehicles stability systems
A number of heavy vehicle equipment manufacturers offer stability systems. Consult your dealer for a list of models that offer these systems.
Be aware manufacturers refer to vehicle stability systems by different names.
The most effective systems target overall instability and can therefore help with preventing both loss of control and rollover crashes. This is best achieved by equipping trucks and prime movers with ESC and trailers with RSC.
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