This paper considers how human factors affect the perception, recognition, and decision process that governs reaction time, with particular regard to the manner in which drivers assess the distance and closing speed to an approaching object. It proposes that such judgements are made in a contextual manner, by relating the position of the object to a perceived frame of reference around it, which can be affected by the texture of the object or its surroundings. This is because we have difficulty recognising or comprehending a change in the angle subtended by a fast approaching object. Therefore we are probably not able to distinguish range solely from the angle subtended by a fast approaching object. The paper then considers situations where driver judgement is made difficult by road features or geometry. This paper aims to assist designers, safety auditors, network maintenance managers and safety inspectors, by making them aware of how drivers make decisions, and what enables them to make better judgements. (Author/publisher)
Abstract