Effects of forward collision warning, initial time headway and repeated scenario exposure on driver response in emergency lead vehicle braking scenarios

Mikael Ljung Aust
Johan Engström
Matias Viström
Arne Nåbo
Anne Bolling
Laban Källgren

To address the research questions, acritical lead vehicle braking scenario and anFCW 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 simulatorin Linköping, and the effects,of FCW presence, two different initial time headways at visual distraction task onset and repeated scenario exposure, on driver response timeswere examined.The study showed significant effects of FCW and repeated scenario exposure on response times. Moreover, these effects were not additivei.e. a significant interaction between the two was found. There was also a significant effect on responsetimes ofinitial 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. 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. In general, theresults from this project have important implications for the interpretation of driver performance in experimental settings, particularlywhen aiming toevaluate safety-related in-vehicle information and warning technologies. For onething,they pose a general question markaround the generalizabilityof results to real world events. Second, a future prerequisite for FCW studies should probably be that test drivers have a previous level of system exposure level which matchesthat of real world drivers encountering typical critical events. Also, tuning the initialtime headwayat distraction task onsetin the experimentalsetting to real world conditions is of critical importance.



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