One of the five most common crashes on Australian roads are when vehicles run off the road on a curve, and in several of these cases the vehicle rolls over. This type of crash is usually caused by drivers going to fast.
To make matter worse, the higher the speed, the higher the rollover force. Comparatively, travelling around a bend at 90km/h compared to 30km/h increase risk of rollover by eight times. In general terms, double the speed means four times the amount of cornering forces. Speed is also an issues when travelling in a straight line, so at 100km/h, any little correction would have a rollover force at four times what the same manoeuvre would have at 50km/h.
In addition to speed, other cause of rollovers include: worn-out or faulty brakes, driver distraction, fatigue, loads shifting, and the type of vehicle.
This issue is not specific to any type of vehicle, however, it is more common for trucks. Drivers of cars, SUVs and vans typically feel when the vehicle’s wheels lift off the ground as a rollover starts and have an opportunity to correct it. This isn’t the case for heavy vehicles. Contrary to popular belief, a heavy vehicle’s trailer will usually start rolling before the prime mover does. The driver is usually not aware that their trailer has started rolling over and by the time that they become aware and start trying to correct and brake, it is too late.
In Victoria, from 2003-2007, 10% of all truck crashes were rollovers, with 47% of these occurring on a bend. The National Transport Institute (NTI) indicated that from 2003-2007 in Australia: 60% of rollovers involved semi-trailers, 41% of rollovers involved inappropriate speed, and 30% of rollovers involved fatigue. Research has shown that fatalities and significant injuries are more likely in rollovers rather than other crashes involving bulk tankers.
There are several new safety technologies which can assist with rollovers. Electronic Braking and Stability Control Systems have been shown to drastically decrease the likelihood of rollovers.
The best way to avoid a rollover is to slow down around curves, and ensure you drive to a speed suitable for your vehicle.
For more information of these issues, see the following NRSPP resources:
- Quick Fact: Get Around Vehicle Rollovers
- Q&A: Bulk Tanker Rollovers
- Q&A: Road Crashes and Trauma to the Human Body
- NRSPP Case Study: VicRoads — Electronic Braking And Stability Control System Eliminates Rollovers