Effects on driver behaviour of the RTI (Road Transport Informatics) system CAROSI (Car Roadside Signalling) providing roadside information on a display inside the car, were studied in a field test. Drivers' opinions about different system aspects were also obtained. Nine subjects between 22 and 59 years, relatively experienced as drivers, participated in the study. Each subject drove a test route in Gothenburg, both in a CAROSI equipped car, and in a conventionally equipped car. Generally, the subjects' attitudes to CAROSI were positive, because the system seems to fulfil a need without bringing too much of disturbance. The subjects found the presented information easy to detect and recognize, even if problems could occur due to low visibility in heavy sunshine. The majority also believed that traffic safety, for instance in terms of their own tendency to follow posted speed limits, could be positively influenced by the introduction of a CAROSI-type system. At the same time the subjects denied that CAROSI had influenced their speed choice during the experiment. They also expressed some safety related worries, as they experienced that they, compared to the conventional dashboard, looked at the CAROSI dashboard more often and for longer periods. This experience was confirmed by a recorded increase in the number of fixations to the CAROSI dashboard (on the average 204 during a test route lap), compared to the (on the average 93) fixations to the conventional dashboard. No speed level differences could be detected, and subjects obeyed the posted speed limits very closely. Subjects' knowledge about passed road signs revealed that the information presented via CAROSI was read and interpreted. To conclude, the possibilities for a CAROSI-type system to be accepted and used by drivers seem to be good. However, CAROSI seems to have an impact on drivers' visual behaviour that can influence traffic safety negatively. Suggestions that can improve the situation were discussed.
Samenvatting