The significance of public transit in curbing greenhouse gas (GHG) emissions and reducing vehicle miles traveled (VMT) goes beyond its users. Investments in transit infrastructure, coupled with service enhancements and their consequential impacts on urban development (termed as indirect effects), have the potential to foster location efficiency. This concept encompasses the advantageous proximity of vital destinations such as workplaces and retail establishments to the residences that necessitate access. In this context, investments made in public transit systems exhibit a multiplier effect, commonly quantified as the reduction in VMT per each passenger mile of transit usage. While this topic has gained attention over the past few decades, an agreement regarding the size of the multiplier effect has yet to be reached among researchers. This study employs a multilevel structural equation model and leverages a comprehensive database of household travel survey data from 31 diverse regions. By utilizing trip-level data, this study provides results that possess external validity and generalizability, overcoming limitations identified in earlier research. Additionally, this study aims to present a simplified formula that enables transit agencies nationwide to compute their unique multipliers. The findings suggest that regions with extensive transit systems exhibit higher transit multipliers compared to regions with limited transit access. Furthermore, the impact of transit within a community extends well beyond merely the reduction in private vehicle usage by transit passengers. Rather, the alterations in the built environment in transit-served communities lead to substantial VMT savings, surpassing the effects solely attributed to transit passenger usage.

公共交通在遏制温室气体 （GHG） 排放和减少车辆行驶里程 （VMT） 方面的重要性超出了其用户的范围。对交通基础设施的投资，加上服务增强及其对城市发展的间接影响（称为间接影响），有可能提高选址效率。这个概念包括工作场所和零售场所等重要目的地与需要访问的住宅的有利接近。在这种情况下，对公共交通系统的投资表现出乘数效应，通常量化为每乘客使用一英里公交的 VMT 减少。虽然这个话题在过去几十年中受到了关注，但研究人员之间尚未就乘数效应的大小达成一致。本研究采用多级结构方程模型，并利用来自 31 个不同地区的家庭旅行调查数据的综合数据库。通过利用 trip level 数据，本研究提供了具有外部有效性和普遍性的结果，克服了早期研究中发现的局限性。此外，本研究旨在提出一个简化的公式，使全国的交通机构能够计算其独特的乘数。研究结果表明，与交通使用受限的地区相比，拥有广泛交通系统的地区表现出更高的交通乘数。此外，社区内公交的影响远远超出了公交乘客减少私家车使用量。相反，公交服务社区建筑环境的改变导致了大量的 VMT 节省，超过了仅归因于公交乘客使用的影响。