What factors influence drivers' response time for evasive maneuvers in real traffic?

Distraction and inattention contribute to 80% of traffic accidents by delaying or hindering driver responses. However, distraction and inattention are not the only factors increasing response times. In addition, the extent to which different factors-related to the driver, the vehicle, or the environment-influence response times in real traffic is still uncertain. Such knowledge may significantly help the development of countermeasures to distraction and inattention. Naturalistic driving data promises to help determine the causes of distraction and inattention by understanding driver behavior in real traffic. Further, large naturalistic datasets are now publically available from a few sources such as UMTRI (University of Michigan Transportation Institute) and VTTI (Virginia Tech Transportation Institute). However, analysis of such data is made difficult by the intrinsic nature of the data: it is large and complex and the variables of interest are hard to control. This study used the public 100-car and 8-truck naturalistic data from VTTI to show how the NatWare toolkit developed at SAFER (Vehicle and Traffic Safety Center at Chalmers) can be used to determine the influence of several factors on response time. Among these factors, attendance to secondary tasks and eyes-off-road, which are indicators of driver's distraction and inattention, significantly delayed response times; the type of incident and response maneuver also affected response times; and finally, truck drivers responded more quickly than car drivers.