Assessing Drivers Ability to Carry Out Headway Advice in Motorway Car Driving

Abstract

In order to improve throughput on motorways, a headway advisory system is being developed. This system could enable drivers to choose their headway differently by providing in-vehicle advice. How well are drivers able to follow a time or a distance headway advice and what effect has vehicle speed and advised headway on their ability? To test this, a group of 20 participants completed nine headway adjustment tasks in a driving simulator experiment. Half of the participants received a time headway advice and half received a distance headway advice. The absolute difference between the advised and the chosen headway acted as a performance measure. In the experiment no performance difference could be found between the driver’s carrying out target headway and those carrying out distance headway advice. Furthermore increasing vehicle speed significantly reduced the driver’s ability to carry out headway advice. This effect was not found for target headway. High inter-driver difference in headway estimation led to high standard deviations in estimation error. Apart from reducing the average estimation error, the support system under development should also focus on reducing the variance in chosen headways.