The effect of lead vehicles on speed choice under restricted sight distances

This study deals with the effect of restricted sight distance on drivers speed choice. It is hypothesized that speed choice is dependent on uncertainties with respect to road way preview. In two experiments the importance of uncertainty about the ability to respond adequately to a slow moving lead vehicle on speed choice is explored. In the first experiment the effects of lead vehicles' speed and sight distance were investigated because both factors might affect the ability to respond adequately. In the second experiment both the preview distance towards lead vehicles and the sight distance with respect to the road geometry were varied independently. Thus, the information relevant for the uncertainty about lane keeping was varied and the relative contribution was established.