The European MASTER project (MAnaging Speeds of Traffic on European Roads) aims to provide recommendations for speed management strategies and policies and develop guidelines for the development of innovative speed management tools. This document describes a driving simulator experiment carried out within Workpackage 3.2 (Evaluation of in-car speed limiters). The University of Leeds Advanced Driving Simulator was used to test two speed control systems against an advisory system and a baseline control (no system). The speed control systems were both designed to prohibit exceeding the external speed limit; one of the systems additionally applied further speed reduction in hazardous situations, such as sharp horizontal curvature and poor weather conditions. The advisory system provided information to the driver regarding appropriate speeds via an in-car display. A road environment incorporating urban, rural and motorway scenarios allowed the comparison of the systems across road types. Driver behaviour under the two control systems was compared to that in the advisory and baseline conditions. Behavioural parameters measured include speed and its derivatives, time headway, overtaking manoeuvres, traffic light violations and collision measures. Subjective measures of workload were taken to monitor any possible underload or overload effects, and an acceptability questionnaire was administered to ascertain driver opinion about the systems. Results indicate that there are safety benefits of control systems including a reduction of maximum speed, speed variance and inappropriate speed at hazardous locations. In addition it was found that the advisory system performed well, especially where the driver could perceive the relevance of that information. However, there were observed secondary effects of the speed control system which may compromise any safety benefits. Such effects included a higher incidence of short time headways, delayed braking and a higher incidence of collisions. Subjective mental workload scores did not differ between the conditions, but it was shown that drivers found the advisory system more acceptable than the control systems. (Author/publisher)
Samenvatting