Micro Traffic Simulation Approach to the Evaluation of Vehicle Emissions on One‐way vs. Two‐way Streets: A Case Study in Houston Downtown

摘要

Vehicles that run on one-way or two-way streets may generate totally different emissions. One3way streets can reduce the amount of conflicts between vehicles going to different directions, butsometimes create circuitous routes which may increase Vehicle Miles Traveled (VMT) andtravel times, thus may increase emissions. Two-way streets can avoid circuitous routes, butcreate slower traffic due to the existence of more moving conflicts between vehicles, which maylead to increased stop, acceleration-and-deceleration activities, thus may also increase emissionsbut at a different degree. Further, regularities of such emission increases may be different forpeak vs. non-peak hours. This paper intends to evaluate vehicle emissions for one-way and two10way streets for peak vs. non-peak hours to investigate which street configuration producesrelatively lower emissions, attempting to help traffic engineers decide whether a conversionbetween one-way and two-way streets contributes to the improvement of air quality. The micro13traffic simulation model—VISSIM—is utilized to output the second-by-second speed andacceleration data for the purpose of emission estimation. The operating mode binning approachis used to calculate emission factors, and differences of generated emissions are adopted as themeasure of effectiveness. The analysis shows that the two-way street network produces loweremissions, thus can better improve the air quality during non-peak hours. However, suchimprovement will be weakened during peak hours. Further, emissions from the two-way streetnetwork may eventually exceed those from the one-way street network when the traffic demandincreases to certain level.