Earlier work within the project had identified three major areas of application that should be subject of safety-related evaluations, namely (i) inter-urban traffic management, (ii) travel and traffic information and (iii) driver assistance and co-operative driving (see Rothengatter et al., 1993). Within the area of travel and traffic information, route guidance systems were identified as relevant and feasible for evaluation. Consequently, route guidance evaluation studies were designed (Grayson & Carsten, 1994), which can divided in two major categories, i.e. on-road experiments and observations, and simulator studies. This report describes the simulator studies that were carried out within this framework. The aim of the experiments was to study the effects of route guidance systems under closely controlled circumstances, as a complement to on-road studies where this is not achievable. The route guidance systems were modelled as closely as possible. Display messages and timing were modelled after operational units and in one experiment the experimental route was modelled after the route driven in the on-road experiments to ensure optimal compatibility. Three separate experiments were carried out. The objectives of the first study were to determine the effects of driving with route guidance information on the visual search of drivers and to determine the effects of display complexity. Drivers had to drive with a route guidance system that displayed simple or complex geometrical information and with or without landmark information. Indicators used included (i) variables concerning glance duration; (ii) navigation errors and (iii) subjective preferences. The objectives of the second study were to determine the effects of driving with route guidance information as compared to map-based information on vehicle control and driver workload. Drivers were required to drive a 25 km route modelled after the on-road studies. Indicators used included (i) navigation errors; (ii) speed choice and variation; (iii) lateral position control; (iv) workload measures and (v) general assessment scales. The objectives of the third study were to determine the effects of different types of route guidance systems on driver interactions and conflicts. Drivers had to drive with route guidance that either did or did not present lane information. Indicators used included (i) workload measures; (ii) driver comfort measures and (iii) driver interaction and conflict measures. (A)
Abstract