The Dutch Ministry of Transport, Public Works and Water Management conducts a project in the area of Lane Departure Warning Assistant (LDWA): a system that will warn the driver for unintentional lane departures, such that the driver will be able to correct the vehicle's course in time. Since effects of LDWA on traffic safety and traffic perform programme is foreseen. One work programme is foreseen. One workpackage focuses on the potential of LDWA in combination with narrow lanes. Narrowing lanes (possibly dynamically) on motorways aims at increasing the capacity, whereas LDWA might make it possible to reach this goal while maintaining or even improving traffic safety. The first step, of which this report is the result, consisted of reviewing current knowledge on the effects of lane width on driving behaviour. The existing knowledge was investigated on the basis of a literature study. The findings were categorised in effects of lane width on several driving behaviour variables: driving speed, mean and standard deviation of the lateral position, Time to Line Crossings, and line crossings. Effects of lane width on driving behaviour have been investigated in many studies. The relationships between lane width and speed and between lane width and the individual driver's standard deviation of the lateral position are quite consistent across the literature. Both variables decrease when the lane width is reduced. For other driving behaviour variables, effects are more ambiguous. Obstacles (barriers, guide rails, other traffic etc.) that are present outside the lane markings also influence driving behaviour. The effect is often a (temporary) shift of the lateral position, sometimes accepting lane exceedance in the process, and/or a reduction in speed. The more ‘threat' these obstacles impose, the stronger is the effect on behaviour, up to a level where the obstacle dominates the effect of the lane markings. In terms of workload, an additional load on the lateral task (e.g. by lane width reduction) or other tasks can be compensated for by a reduction of speed. However, adding additional tasks to the driving task has yielded effects that appear to be counter-intuitive: when adding cognitive loading tasks, lateral control improved. Furthermore, the reduction in speed due to the lane width reduction was not influencedinfluencede additional task. Such effects can be explained by an increase of total effort and/or a change in control strategy. This once again demonstrates that the effect of combined influences is difficult to predict. In the literature, an increasing number of publications in the area of LDWA has appeared the last few years. However, no results have been found concerning the specific combination of LDWA with narrow lanes. Quantitative experimental results have shown that, in accordance with observations from practice, various elements in the road design have specific effects on driving behaviour. Hence, a reliable prediction of the effect of very new elements, or a new combination of existing elements, can not be expected solely on the basis of existing knowledge. (Author/publisher)
Abstract