中文摘要：

机动车污染排放评价是交通项目决策的重要依据,但目前研究方法难以揭示交通空气污染在不同空间尺度上（宏观-中观-微观）的影响。采用传统的四阶段交通需求仿真工具,整合最新的污染排放模型,以美国马里兰州高速公路车道改造项目为例,示范了项目实施前后空气污染变化。结果发现虽然在大空间尺度（州域和郡域）上空气污染水平变化几乎可以忽略,但通道沿线的污染排放量有可观增加。研究结论可为我国交通污染排放评价提供技术与方法借鉴。

英文摘要：

Vehicular emission evaluation is an important basis for transportation project decisions, but existing study approaches are limited in revealing multiscale （ maerocosmic, mesocosmic, and microcosmic） impacts of ve hicular air pollution. Traditional fourstep travel demand simulation approach is adopted and integrated with the latest mobile emission model. A case study is given to illustrate the air pollution changes before and after highway lane con versions in Maryland, USA. The results show that although the emission impacts of the project are minor at the state wide and county levels, they are observable at the corridor and lane levels. The study provides guidance to Chinese researchers in developing and applying the new vehicular emission evaluation technologies.