The Michigan Department of Transportation (MDOT) desired to explore the impact that recently completed roadway projects had on automobile, pedestrian, and bicycle safety. Additionally, MDOT wanted to determine to what extent these improvements also impacted mobility for motorists, pedestrians, and bicyclists. Five recently completed roadway improvement projects, or case studies, were selected for analysis. These case studies were analysed to determine the effect of specific improvements on safety and mobility. Roadway improvements included a reduction in the number of travel lanes, also known as a road diet; the installation of raised, non-mountable medians; pedestrian refuge islands; installation of pedestrian signals; roundabouts; curb bump outs; beacons at pedestrian crossings, called rectangular rapid flashing beacons (RRFB); and high visibility pedestrian crosswalk pavement markings. Roadway improvements were implemented along the full length of the corridor and some case studies included specific improvements at select intersections. Generally, the case study analyses did not yield clear results as to the effectiveness of reducing crashes on MDOT roadways. In some instances, sufficient crash data were lacking for the time period after the installation of improvements. In others, the control site performed nearly as well the variable site in terms of reducing crashes, calling into question the effectiveness of the improvement. In one case, a spot improvement resulted in an increase in crashes. The case study analyses revealed that data collection is more difficult to perform after the installation of an improvement than as part of a specific research project. In many of the case studies, it was difficult to determine the impact that an improvement had on crashes. For example, while the road diet and continuous median installations yielded the expected crash reduction results, the improvements that consisted more of a series of spot improvements showed mixed results. In addition, a lack of meaningful before data such as travel speeds and traffic volumes, as well as information about pedestrian and bicycle traffic, made multimodal before-and-after analysis of each corridor difficult. (Author/publisher) For other reports/appendices in this research project, see http://www.michigan.gov/mdot/0,4616,7-151-9622_11045_24249-279311--,00…
Abstract