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Evaluating the Safety and Emissions Impact of Converting One-Way-Stop Intersections to All-Way-Stop Intersections
Molly Behan, Luis Miranda-Moreno, Bismarck Ledezma-Navarro

Last modified: 2019-07-19


Pedestrians and cyclists represent a large portion of sustainable transportation. In order to encourage the usage of these modes, we must ensure users are safe. This research will evaluate the safety and emissions effects on a connected network of the conversion of One-Way-Stop (OWS) intersections to All-Ways-Stop (AWS) intersections with a particular focus on these vulnerable users. For such purpose, a network of 22 intersections in a central borough of Montreal is evaluated through computer microsimulation. Ten of the 22 intersections are part of a before and after study where OWS were replaced with AWS. For the intersections that are part of the before and after study, users’ trajectories were obtained from video data collected. From the second by second information of the video trajectories, speed values (mean, median, 15th percentile and 85th percentile), volumes, and turning ratios were obtained. In order to evaluate the effects of these modifications, the information from the video trajectories was used to calibrate two scenarios of a microscopic model in Vissim. One scenario represents the network before modifications were made, and the other represents the network following the implementation of additional stop signs. Manual traffic counts were used to gather data on intersections required for the microsimulation model where stop control treatments were not made. The outputs from these models were used to run analysis of surrogate safety measures between high-risk users and motorized vehicles using the FHA’s Surrogate Safety Assessment Model (SSAM). Hazardous interactions between motorized vehicles were found to increase in all scenarios evaluated. Hazardous interactions between motorized vehicles and cyclists were found to decrease in medium and high hazard scenarios. An additional aspect of this research involves using data gathered in Vissim to evaluate the additional stop signs’ impact on vehicular emissions. Preliminary results show an increase of all pollutants evaluated due to increased time vehicles spend braking and decelerating. Emissions of Primary Exhaust PM10 and PM2.5 were found to increase nearly 30%. The EPA’s Motor Vehicle Emissions Simulator (MOVES2014b) is being used to complete this portion of the analysis.

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