RAPID: Fare Free Public Transportation - A Full Scale Natural Experiment in Alexandria, Virginia

这项快速反应研究拨款（Rapid）项目将评估免费公共交通和改善网络连通性对乘客人数、私家车行驶里程、温室气体和常规污染物排放、拥堵和交通的影响，并将研究其对不同收入群体和种族的分配影响。该项目基于在弗吉尼亚州亚历山大市进行的全面自然实验，当地交通机构DASH （Driving Alexandria safety Home）决定在其服务区域内实施免费公共交通计划，主要是出于公平和公平的考虑。这样的自然实验将基于从研究区域和一个或多个控制地点收集的数据-当项目到位时，并对其实施前的适当时期进行回顾性分析-以适当评估其成就和效果。调查计划将包括DASH系统的用户以及处理地点的普通公众，以了解实际或潜在的旅行，一般的旅行模式，以及免费是否取代了私家车旅行和排放，或其他交通方式。数据收集计划将辅以对管制地点的公共交通用户和一般公众的平行调查，以获得类似的信息，以及如果公共汽车免费，他们打算使用公共交通的情况。这项研究及其结果可能会影响政策建议和基础设施投资决策，这将影响我们未来的交通系统和美国公民的生活质量。这个项目的影响在目前尤其重要，因为过境使用正在从大流行中缓慢恢复，尚未达到大流行前的客流量和出行方式比例，而且本届政府和国会正在考虑为基础设施提供大规模资金。从方法学的角度来看，该研究涉及到从概率和非概率样本中抽样、分析和建模数据的统计程序。挑战包括采样权的构建，控制位置的选择，匹配处理对象和控制对象以确保有效的统计推断等等。一个由工程、经济学、调查方法论和数学等学科的教师和学生组成的多学科团队将在调查设计、数据链接、计量经济模型估计、旅行行为和政策分析等方面进行合作。该项目有望成为其他地方类似项目的概念证明，并将成为许多交通机构实施创新政策计划的参考，以增加客流量和可达性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This Grant for Rapid Response Research (RAPID) project will assess the effects of free public transit and improved network connectivity on ridership, miles driven by private vehicles, emissions of greenhouse gases and conventional pollutants, congestion and traffic, and will study its distributional effects on different income groups and ethnicities. The project is based on a full-scale natural experiment conducted in Alexandria, Virginia, where the local transit agency DASH (Driving Alexandria Safely Home) has decided to implement a fare-free public transportation program over its service territory, motivated primarily by fairness and equity considerations. Such a natural experiment will be based on a data collection the study area and from one or more control locations—while the program is in place, and retrospectively for a suitable period before its implementation—for a proper assessment of its accomplishments and effects. The survey plan will involve both users of the DASH system as well as members of the general public at the treatment location to understand actual or potential travel, general travel patterns, and whether the fare free has displaced private car travel and emissions, or other transportation modes. The data collection plan will be complemented with parallel surveys of transit users and members of the general public at the control locations to elicit similar information and their intended use of transit if the bus became free. This research and its results may influence policy recommendations and infrastructure investment decisions that will impact the future of our transportation system and the quality of life of citizens in America. The impacts from this project are especially relevant at this time, when transit use is slowly recovering from the pandemic and has not yet reached pre-pandemic ridership and travel mode shares, and when large-scale funding to infrastructure is being considered by this Administration and the Congress.From a methodological perspective, the study involves challenging statistical procedures in terms of sampling, analyzing, and modeling the data from both probabilistic and non-probabilistic samples. Challenges include the construction of sampling weights, the selection of control location, matching treated and control subjects to ensure valid statistical inference, and many others. A multi-disciplinary team composed by faculties and students in engineering, economics, survey methodology and mathematics will work collaboratively on survey design, data linkage, econometric model estimation, and travel behavior and policy analysis. The project is expected to be serving as a proof of concept for similar programs elsewhere and will be a reference for the many transit agencies implementing innovative policy schemes to increase ridership and accessibility.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.