This paper presents the results of a study which examined accident modification factors for median bus lanes on urban arterials. Although taken for granted that median bus lanes will boost bus ridership and relieve traffic congestion, the full utilization of this useful design is not undertaken because highway engineers often are concerned with the increase of crashes in median bus lanes. However, the installation of the median bus lanes does not always lead to an increase in crashes and, to demonstrate that this argument is correct, this research proposes the use of accident modification factors. The following tasks were carried out: first, aliterature review of the major geometric elements of median bus lanes was undertaken. Second, both existing crash and geometric information data were gathered. Third, a statistical analysis was made to examine the effects of crash occurrences on major geometric elements. In addition, the crash models resulting from this analysis were subsequently applied in developing accident modification factors. A verification process was also carried out. As a result, it was found thataccident modification factors for median bus lanes could be successfully developed, and that crash occurrences were very sensitive to the widths of the bus lane, the travel lanes and the shoulders, in that order. The findings from this research should be useful in comparing several safety design alternatives in the future. (Author/publisher)
Abstract