Abstract Many US metropolitan areas have undergone dramatic shifts in socioeconomic organization.. As urban areas gentrify, many low-income residents and communities of color have transitioned towards the exurban periphery. These suburban neighborhoods tend to have fewer employment opportunities and are fairly disconnected from public transportation networks serving the urban core. Using regional transportation plans (RTPs) for three California MPOs, we show that the transportation accessibility and environmental health issues affecting these exurban communities are unique and inadequately captured by the MPOs' current equity metrics. MPOs performance evaluation is regional and achieving equity within the urban core communities will not address emerging equity, accessibility and air quality concerns for exurban communities. With a brief history and a focused case study of RTPs for the San Francisco Bay Area, San Diego, and Fresno, we examine how air pollution, equity, and transportation interact in three different types of 21st century cities. We find that when allocating limited transportation funds, California metropolitan planning organizations (MPOs) prioritize the improvement of existing public transportation in urban core areas over expansion of transit networks towards disconnected exurbs. This approach is an effective way to reduce vehicle miles traveled (and thus, air pollution) at the regional level due to high population concentrations in urban cores. However, this approach also concentrates the air quality benefits of VMT reduction in these same urban core areas. Exurban residents' on-road and near-road exposure to Traffic-Related Air Pollution (TRAP) will not be reduced by improving public transit within the urban core. We argue that although these suburban and exurban communities are a small percentage of the regional population, they have a right to share in the benefits of transportation investments, particularly given the historical and ongoing patterns of displacement and economic exclusion from urban core areas.

中文翻译：

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我们跟上了吗？区域规划中的可达性、公平性和空气质量

摘要 美国许多大都市地区的社会经济组织发生了巨大变化。随着城市地区的高档化，许多低收入居民和有色人种社区已向郊区边缘过渡。这些郊区社区的就业机会往往较少，并且与服务于城市核心的公共交通网络相当脱节。使用三个加州 MPO 的区域交通计划 (RTP)，我们表明影响这些郊区社区的交通可达性和环境健康问题是独一无二的，并且 MPO 当前的公平指标没有充分体现。MPO 的绩效评估是区域性的，在城市核心社区内实现公平不会解决郊区社区新出现的公平、可达性和空气质量问题。通过对旧金山湾区、圣地亚哥和弗雷斯诺的 RTP 的简要历史和重点案例研究，我们研究了空气污染、公平和交通如何在 21 世纪三种不同类型的城市中相互作用。我们发现，在分配有限的交通资金时，加州大都会规划组织 (MPO) 优先考虑改善城市核心区现有的公共交通，而不是向不连贯的郊区扩展交通网络。由于城市核心区的人口高度集中，这种方法是在区域层面减少车辆行驶里程（从而减少空气污染）的有效方法。然而，这种方法也将 VMT 减少的空气质量优势集中在这些相同的城市核心区。远郊居民 通过改善城市核心内的公共交通，不会减少道路和近道路对交通相关空气污染 (TRAP) 的暴露。我们认为，虽然这些郊区和远郊社区只占区域人口的一小部分，但他们有权分享交通投资的收益，特别是考虑到历史和持续的流离失所和经济被排斥在城市核心地区的模式。