The safety effects of driving speed have been frequently investigated by studies based on statistical data. While statistical studies provide valuable information on the average safety effects of driving speed, they do not reveal how the driving speed influences driver behaviour, and thereby traffic safety. This may be one reason why some results of statistical studies have been unacceptable and inconceivable for some drivers. One may argue, for example, that these studies are invalid, because they do not take into account the differences between drivers. Consequently, in the present paper the safety effects of driving speed were investigated from a driver viewpoint. First, the effects of driving speed on each subtask of the driver were analysed. It is shown that each subtask becomes more difficult when the driving speed increases, which increases accident risk. Second, collision kinematics and injury mechanisms were described to show how increased driving speeds increase accident severity. Third, the argument that drivers are capable of adjusting their speed according to situational demands, even without speed limits, is discussed. (A)
Abstract