Surrogate in-vehicle information systems and driver behaviour in an urban environment: A field study on the effects of visual and cognitive load

This field study was designed to investigate and compare the potential or sensitivity of the selected HASTE assessment methods to reflect the effects of different surrogate in-vehicle information systems (S-IVIS) on driver behaviour in an urban environment. Two types of S-IVIS were used, an auditory one representing cognitive tasks and a visual one. The interaction with other vehicles in yielding situations changed somewhat when conducting the secondary task compared to normal driving. Both S-IVIS tasks tended to decrease the proportion of proper yielding of the right-of-way to other vehicles at urban intersections. In addition, the interaction with vulnerable road users was affected by secondary task performance as well. The S-IVIS tasks tended to produce increases in speed before the intersection in cases when there were vulnerable road users present at the urban intersection compared to driving without the secondary task. However, the cognitive task seemed more frequently to cause observed inappropriate behaviour towards vulnerable road users at urban intersections than the visual task. For both S-IVIS tasks, the percentage of correct responses was highest for the static situation and lowest when conducted in urban environment and the percentage of correct responses decreased with increasing task difficulty. In general, the results suggest that driving with a secondary task in an urban environment caused some changes in driving behaviour. In particular, proper interaction with other road users suffered when the driver had a secondary task.