In this paper it is argued that the effects of in-vehicle information systems (IVISs) on traffic safety risk depend on the pacing factor of both the primary driving task and the secondary IVIS task. The effects on traffic safety will probably be lowest when: the driving task is self-paced, in the sense that the driver is able to adjust speed or headway to secondary task demands; and when the secondary task is also self-paced, allowing the driver to process information if and when it suits best. However, traffic safety risk is highest when: the driving task is forced-paced, in the sense that the driver is not able to adjust the driving task being performed; and when the secondary task is also forced-paced. This principle is illustrated by an experiment with a PC test that was designed to evaluate IVISs effects on traffic safety and driver behaviour. The test resembles driving a car in some important aspects: subjects are required to drive on a simulated winding road using a steering wheel, an accelerator and a brake pedal. While driving the subjects interact with an IVIS. The most important indicators of driving performance are vehicle speed and minimum Time-to-Line-Crossing (TLC). (A) See also C 12562 (IRRD E201349).
Abstract