Driving while under the influence of alcohol or drugs, or at excessive speeds are widely considered to be the main causes of serious accidents involving a single vehicle. However, a new in-depth on-scene study in Sweden reveals that driver fatigue, slippery roads, and inexperience could be just as important and should be factored into the design of new vehicle safety features, according to researchers writing in the International Journal of Vehicle Safety.
Jesper Sandin and Mikael Ljung of the Vehicle Safety Division, at Chalmers University of Technology, in Sweden, used the Driving Reliability and Error Analysis Method (DREAM) to dissect the cause and effect of 38 single vehicle crashes that occurred in Gothenburg. They found that the crashes could be grouped into four scenarios.
In the first scenario, vehicles drifted off road or into the oncoming traffic lane due to driver fatigue, sleepiness or distraction. In the second scenario, a loss of traction caused by an undetected slippery surface caused even experienced drivers to lose control in bends, the researchers explain.
They also found that loss of control in driving around a bend was a factor in the third scenario, but this was due partly to the vehicle's high speed. In this scenario, drivers overestimated their driving skills or had limited experience of the vehicle or the bend and so lost control. In the final scenario, panicked drivers lost control of their vehicle as they tried to steer themselves out of trouble and failed through excessive over steering.
Vehicle safety has improved considerably in recent decades with the development of driver and passenger air-bags, side-impact protection devices, wheel antilocking systems, and traction control for improved cornering. However, single vehicle crashes are very unpredictable with incidence of vehicle rollover and collision with solid objects on the roadside leading to significant injury and fatalities.
"Our study demonstrates a methodology that can be used to explain how a combination of factors may increase the risk of single vehicle crashes," the researchers explain. Such an analysis could allow vehicle manufacturers to design new features that can compensate for the causes described in each of the four crash scenarios. The development of sensors for crash prevention and detection and the activation of safety measures such as airbags and pre-tensioning systems could now take into account the many unpredictable factors involved in single vehicle crashes.