Comparative analysis of grade-separated pedestrian infrastructure and at-grade treatments

Project summary:

Grade-separated intersection crossings for pedestrians have potential benefits in terms of reduced pedestrian waiting times at intersections, reduced vehicle delay, and increased pedestrian safety. However, they also have disadvantages: immediate construction costs, recurring maintenance costs including snow removal, possible personal safety concerns for underpasses, and pedestrians may dislike climbing stairs. Overall, grade-separated crossings are appropriate in some locations, but not in others. Some of the factors that might affect whether grade separation is warranted include the number of lanes to be crossed, the volume of pedestrian and/or vehicle traffic, road speeds, and/or visibility. Some locations may be more amenable to grade separation due to natural elevation. If grade separation is chosen, should overpasses or underpasses be used? Where should they be located at the intersection? The purpose of this project is to develop a guidance manual to make these decisions. Extensive simulations of vehicle and pedestrian traffic will be developed and conducted towards the writing of this manual, but researchers anticipate that the outcomes of exhaustive simulations can be reported in a manual for future reference rather than repeated by MnDOT for different intersections. These simulations will consider varying intersection geometries including numbers of lanes and turn bays. They will also vary the vehicle and pedestrian volumes, turn ratios, and speed limits to compare performance. Grade separation will be modeled as a reduction in pedestrian volumes based on the proportion of pedestrians choosing to use the grade-separated infrastructure. The performance benefits will be compared to the costs of grade-separated infrastructure to achieve a cost-benefit analysis. Based on this analysis, and cutoffs determined in collaboration with the technical assistance program (TAP), a manual focusing solely on infrastructure guidance will be written.