Influence of Human Behaviour on Geometric Road Design

AbstractRegarding the annual accident statistics, it becomes evident that the amount of deadly accidents decreased steadily throughout the last decades, whereas the amount of accidents itself remained fairly constant. Therefore one can draw the conclusion that the improvement of passive safety systems is the crucial, impact-inhibiting factor. Hence the next step should take us to the contemplation on how we can eliminate the occurrence of accidents. Taking the psychology into account may be one possible approach on this subject.The content of the thesis, which is the foundation of this abstract, is a capacious, international literature research. More than 450 sources have been analysed, containing the scientific fields of road design, behavioural psychology, gestalt psychology, ergonomics and the evolution of the technical codes.First and foremost, it is necessary to understand the concept of decision-making during a driving-task. The idea of a conscious and rational decision-making while driving is merely wishful thinking and has nothing to do with the actual processes. When we take the performance-model of Rasmussen into consideration, then we have to admit that the actual human performance is taking place in the skill-based area (Rasmussen, 1983), i.e. human operators do not think deliberately about every single action by considering every single possible input, but rather scan unconsciously their environment for hidden signals, which are supporting a certain type of action – human operators are always prone to errors (Kahneman would call this conceptual pair “heuristics and biases”). As a consequence, the road space should be designed according to the expectation the driver has about the forthcoming characteristics. In order to describe gestalt-psychological weaknesses of spatial road alignments, the driver's perspectival view was analysed and divided into several key points and key directions, whose arrangement allow conclusions on how the imperfections emerge and how they influence the driver's evaluation of the road space ahead