Driving simulator study to support design of intersection safety application

The aim of the European research project SAFESPOT is to prevent road accidents by developing a Safety Margin Assistant that extends the drivers´ awareness in space and time. One application of the Safety Margin
Assistant is the Intelligent coopeRative Intersection Safety system (IRIS). IRIS will identify safety critical situations at intersections and generate warning messages to support road users. This paper addresses the interaction of IRIS with the driver. In order to gain knowledge about the timing of the warning messages, a driving simulator experiment was performed before implementing and testing the application in a real-life environment. The objective of the experiment was to gain insight in the time of warning and the way to warn. The examined IRIS scenarios where a normal or police car that violates the red light and a warning for a conflict with a scooter when turning right. The time of warning and the approaching velocities of the red-light violating cars were varied in the study. The study showed that the safety margin increased when the driver was warned for a red-light violator and a possible conflict with a scooter. The earliest moment of warning for the red-light violating cars was preferred when these cars both drove 30 km/h. Two moments of warning have been compared. Furthermore, the study showed perceived differences between the police car and the normal car: a normal car violating the red light was perceived as more dangerous than a police car when both drove 60 km/h, and the perceived warning time for the police car came later than for the normal car when they both drove 30 km/h. Participants indicated that they had a look at the display in 74% of the critical situations, and indicated that they understood the icon ‘a little’. Overall, the results and setting up the experiment itself produced new and valuable knowledge for the design of the system.