Impacts of cross-sectional elements (median configurations and bicycle lanes) at urban arterial driveway location

Studies have revealed that among over 50 roadway-related features, cross-sectional roadway elements are one of the most important in affecting road safety performance. Unfortunately, quantifying the safety for urban road cross-sectional features has historically not received as much attention as it has for rural roads. This paper presents a study on the influences of select cross-sectional related design elements (specifically median configurations and bicycle lanes) and their impact on crash severity and type as well as the associated driver gap acceptance for turning maneuvers at midblock driveway locations on urban arterials. The primary goal of this proposed research is to better understand how the median and bicycle lane configurations can influence safety and operations at driveway locations. The authors utilized crash data, traffic data, and roadway information from driveway locations in Oregon, Arkansas, and Oklahoma in the United States. The project team supplemented the data with digital videos acquired during field studies of the sites. The traffic videos helped the authors better understand how road features and traffic influenced driver behavior at selected urban arterial driveway locations. As part of this effort, the authors conducted gap-acceptance studies to determine the critical gaps for driveway locations at arterial roads with and without bicycle lanes. The authors evaluated four different critical gap analysis methods to estimate the driveway operations and noted potential procedural biases associated with two of the techniques. The paper describes these field studies and summarizes how the gap acceptance varied at the different arterial driveway locations.