A critical lead vehicle braking scenario and an FCW system was developed and pilot tested in Saab’s fixed based driving simulator in Trollhättan. After piloting, the scenario was implemented in VTI’s moving base simulator in Linköping, and the effects, of FCW presence, two different initial time headways at visual distraction task onset and repeated scenario exposure, on driver response times were examined. The study showed significant effects of FCW and repeated scenario exposure on response times. Moreover, these effects were not additive i.e. a significant interaction between the two was found. There was also a significant effect on response times of initial time headway at onset of the visual distraction task. In addition, an interaction between initial time headway and repeated scenario exposure was found for drivers with FCW, but not for drivers without FCW. Overall, the study shows that when measuring the effects of an FCW in an emergency lead vehicle braking scenario, the effect size seems to be governed by on one hand the timing of the warning, and on the other hand by the transparency of the scenario for drivers who do not receive a warning (how easy it is to understand that something critical is about to happen). If the warning comes late and the scenario is easy to predict, effects of FCW on response times will be small, and vice versa. Also, the study shows that exposure to the FCW system has a large influence on response times. The unknowing driver seems to respond only to the scenario and not to the warning, but the first exposure is enough to teach the driver to respond to the FCW in the following scenarios. A second objective of the project was to compare the extent to which the VTI moving base simulator with motion cues generates similar driver responses (quantitatively and qualitatively) as the static simulator set-up at Saab. As the number of pilots in Trollhättan was limited to 11 people in total, of which 6 were baseline drivers with complete data sets, these comparisons are to be considered tentative and qualitative rather than quantitative and absolute. On that level the data seem to indicate that baseline drivers in the fixed base simulator show the same type of improvement, in response time and reduction in maximum brake pressure over exposures, as drivers in the moving base simulator, but not the same response difference between the long and short initial time headway conditions. (Author/publisher) This report may be accessed by Internet users at http://www.vti.se/en/publications/effects-of-forward-collision-warning-…
Abstract