TRL has conducted a set of experimental trials on behalf of the UK Department of Transport with the aim of directly comparing individual drivers' performance of the same driving tasks in an instrumented vehicle and in a driving simulator. Over fifty members of the public drove in each environment for two half-hour sessions, alternating between the real TRL test track and a computer-generated simulation of it. Forty-seven subjects produced useable results in both environments. The set of simple driving tasks chosen for this experiment included speed estimation and maintenance with and without a speedometer, lane-keeping, headway maintenance and reaction to an in-vehicle display. In addition to set tasks, drivers' estimations of safe speed and safe headway were recorded in both environments to compare personal perceptions of risk. Braking tests were also conducted in both environments, to test drivers' ability to brake smoothly to a specified position under normal and harsh braking conditions. The majority of experimental effects observed on the real track were also detected in the simulated environment, although between-subject variation was larger in the simulator. The visual distraction task, in particular, appeared to cause greater degradation of steering performance in the simulator due to the more demanding nature of the steering task. The results of a post-experimental questionnaire confirmed the objective findings by identifying tasks which feature lateral or longitudinal acceleration, such as curve-following and smooth braking, as the most demanding aspects of driving the simulator.
Samenvatting