One traffic safety problem that has been observed in several studies is the wear of the windscreens. The risk of dazzling increases when driving with a worn windscreen, which may have the consequence that the driver does not discover objects or people on the road in front of the vehicle. In this simulator study driver behaviour has been studied using three windscreens, one driven 150 000 kilometres, another driven 350 000 kilometres and one unused. The experiment has a within groups design. In this case this means that all 24 test persons drive under each experimental condition, i.e. everyone with each of the three windscreens. The driver passes two obstacles during each drive. To achieve dazzling in the driving simulator a lamp was mounted in front of the windscreen in the simulator. The lamp simulated a setting sun. The sight length to a cone was measured. The results showed that the sight length became shorter with a worn windscreen. The difference in sight length between the unused and the most worn windscreen was on average 131 metres (±22 metres), implying a reduction in sight length of approximately 65 percent. When the driver had to make way for an obstacle on the road, this was more difficult with a worn windscreen. The drivers discovered the obstacles later, used a harder brake power and took a more powerful action to avoid the obstacle, despite the fact that the average speed was decreased with approximately 15 kilometres per hour. Altogether this indicates a more risky driving behaviour, in other words decreased traffic safety. Some of the drivers were not able to avoid the obstacle at all and hence collided. None of the obstacle passes, while driving with the unused windscreen, led to any collision, but four percent led to a collision while driving with the windscreen used in traffic for 150 000 kilometres and eight percent led to a collision with the windscreen used in traffic for 350 000 kilometres. However, due to the low number of observations there was no point in performing any statistical analysis. Still, the results indicate that driver behaviour and safety margins are severely effected by worn windscreens. Considering that in real traffic these events had been traffic accidents the results are alarming and show that driving with worn windscreens in dazzling conditions can be dangerous. When the drivers were asked to express their opinion about the experiment, they assessed both the simulated environment and the driving task as relatively realistic. Even though this is a simulated situation, with its limitations, the results indicate that driving with a worn windscreen has negative effects on driver behaviour. The problem may be even greater in real traffic since there are other factors, such as mud and rain that effect sight and dazzle. Already with a windscreen used during 150 000 kilometres the driver behaviour is negatively effected. Since there are probably a considerable amount of vehicles in traffic with windscreens that has been used 150 000 kilometres or more, the problem with worn windscreens should be taken seriously. (Author/publisher)
Samenvatting