The high vehicle congestion is the main contributing factor to air pollution originated from the engine's combustion in many urban areas. Grade separation projects have been used to solve this problem and have resulted in overall air pollution reduction in many cases. Many grade separation projects are constructed near sensitive urban locations accommodating susceptible individuals. This research argues that in such cases in addition to the overall air pollution reduction, air pollution concentration near sensitive locations is an influential factor for deciding the appropriate scenario. This research proposes a complementary simulation-based method for assessing the resulting pollution concentration of the new grade separation projects near sensitive locations. In this method, traffic congestion and air pollution of the different available project scenarios were simulated and compared. The recommended scenario was selected as a trade-off between the resulting traffic congestion, the amount of air pollution, and air pollution concentration near sensitive locations. The proposed method was applied to an actual grade separation project in Dezful, Iran using VISSIM and EnViVer traffic and air pollution simulation software packages. It was shown that air pollution concentration near sensitive locations could be reduced by up to 40% with no significant change to the overall air pollution and the average vehicle speed. The achieved results in the case study uphold the pollution concentration near sensitive locations as a possible influential factor in the grade separation projects. The proposed method targets a new aspect of the grade separation projects assessment. As a result of the proposed method implementation, unintentional adverse impacts of air pollution can be avoided on the susceptible groups of citizens. The similar method proposed for the grade separation projects in this project can be adapted for other types of urban transportation projects.

高度的车辆拥堵是导致空气污染的主要因素，在许多城市地区，空气的污染源于发动机的燃烧。等级分离项目已被用来解决这个问题，并在许多情况下导致总体空气污染的减少。许多等级分离项目是在敏感城市地区附近建造的，以容纳易感人群。这项研究认为，在这种情况下，除了总体上减少空气污染外，敏感位置附近的空气污染浓度也是决定适当方案的影响因素。这项研究提出了一种基于补充模拟的方法，用于评估敏感位置附近新等级分离项目的污染浓度。用这种方法 模拟并比较了不同可用项目场景的交通拥堵和空气污染。选择推荐的方案是在导致的交通拥堵，空气污染量和敏感位置附近的空气污染浓度之间进行权衡。使用VISSIM和EnViVer交通和空气污染模拟软件包，将该方法应用于伊朗Dezful的实际等级分离项目。结果表明，敏感位置附近的空气污染浓度最多可降低40％，而总体空气污染和平均车速没有明显变化。案例研究中取得的成果表明，敏感区域附近的污染浓度可能是等级分离项目中可能的影响因素。所提出的方法针对等级分离项目评估的新方面。通过提议的方法实施，可以避免空气污染对易感人群的意外影响。为该项目中的等级分离项目建议的类似方法可以适用于其他类型的城市交通项目。