This project's goal was to explore cyclists' visual and acoustic perception of road traffic, and to identify types and causes of perceptional errors. A literature analysis was conducted to summarize the state of knowledge. Though not a lot is known about cyclists' visual perception and even less about their acoustic perception, an increasing number of studies dealing with these research questions have been conducted over the last years. An accident analysis based on data from the German-In-Depth-Accident-Study was conducted to find out how many accidents are due to perceptional errors, and which factors contribute to it. 1232 accidents (mainly) caused by cyclists were analysed to identify type, frequency and possible causes of perceptional errors. In one of four accidents a visual perceptional error of the cyclist (not once an acoustic error!) was reported when describing the course of events. In order to identify which environmental and personal factors contributed to the occurrence of perceptional errors an explorative analysis was conducted. They occur more often: - When turning into or crossing an intersection, - At driveways and side roads, - At daytime, - With cyclists younger than 15 years of age. They do not occur more often: - In bad weather conditions (e.g. rain, fog), - With cyclists older than 55 years or older than 75 years of age, - When (unadjusted) impairments of sight were reported. This might be explained by e.g. compensation strategies or methodical artifacts. Rarely reported were distractive activities (underreporting quite likely), which could not be checked for correlation with perceptional errors due to low case numbers. The lack of useful information in many descriptions of the accidents' course of events hinders the ex post analysis of perceptional errors. A task analysis was conducted to assess the ways in which cyclists manage different traffic situations. Special interest was given to their typical perceptional and cognitive processes and the workload resulting from them. Each situation was video-recorded. Test persons were instructed to "think aloud", where or what they look at or listen to, which decisions they make, how they would act, which factors influence all this, and how demanding these tasks would be in real traffic. The results provide insight into typical perceptional processes of cyclists: e.g. the change from mainly stimulus-driven attention when certain environmental cues are noticed to focussed attention, the acoustic monitoring of rearward traffic, cyclists' awareness of the error-proneness of acoustic perception which are complemented by control glances – if there is enough time left. An expert workshop was conducted to discuss measures to increase the traffic safety for cyclists and further needs for research. Measures for preventing perceptional errors resulting from the following causes were discussed: - Inattention and distraction, - Insufficient design of the traffic environment, - Limited skills or willingness to cycle safely. During the discussion measures were identified which support cyclists’ perception, their situational assessment, their awareness of and compliance with safe cycling behaviour in road traffic. Further research needs were pointed out, e.g. the evaluation of road safety measures, and the comprehension of visual and acoustic perception of cyclists. (Author/publisher)
Samenvatting