This study's main objective was therefore to examine whether the presence of a FCW system affects driver response times in emergency braking scenarios, and if there is an effect, whether it is moderated by repeated scenario exposure.
A critical lead vehicle braking scenario was implemented in a moving-base simulator, and the effects on driver response times of FCWpresence, two different initial time headways at visual distraction task onset and repeated scenario exposure were examined.
Overall, the study shows that when measuring the effects of a FCW in an emergency lead vehicle braking scenario, the effect size is governed by on one hand the saliency and timing of the warning, and on the other hand by the transparancy of the scenario for drivers who do not receive a warning. Also, the study shows that previous experience of the FCW system has a huge influence on driver behaviour; the unknowing driver responds only to the scenario and not at all to the FCW, while the trained and trusting driver responds primarily to the FCW and to a lesser extent to the scenario.
Ljung M., Engström J., Viström M., Andersson A., Bolling A., Hjort M., Jansson J., Källgren, L. (2009). Effects of forward collision warning, initial time headway and repeated scenario exposure on driver response in emergency lead vehicle braking scenarios. VIP Rapport (in-print), Linköping, Sweden.
Photo: Katja Kircher