Staging at the Curb: Evaluating the impacts of shared automated vehicle fleet operations under curb usage restrictions

Shared automated vehicle (SAV) ridehailing services are now operating in several metropolitan regions in the United States. While providing benefits, SAV services may exacerbate issues related to curb usage and vehicle kilometers traveled (VKT) in urban areas. The objective of this study is to provide guidance to cities by evaluating the impacts of SAVs’ short-term curb usage for staging between serving ride requests, under different curb restrictions and SAV operational strategies. We focus on the following performance metrics: VKT, curb productivity, customer wait time, and customer matching rate. To perform the analysis, we use a high-fidelity commercial simulation tool that models the dynamics of SAV fleet operations. We use high-quality, high-resolution data, including synthetic ridehailing trip data and forecasts of curb availability at each curb front in San Francisco, California. Our baseline scenario assumes a hypothetical fleet of 1700 vehicles serving 68,000 daily trips. We construct scenarios that vary in whether, where, and when SAVs can stage at curbs, as well as whether they strategically reposition to high-demand areas. We also vary the day of the week. According to our simulation results, excluding SAVs from staging at the curb would increase daily VKT by more than 200,000 km, a nearly 60 percent increase compared to scenarios in which SAVs can stage at the curb. In a separate analysis, we find that prohibiting SAV curb staging in residential areas and on curbsides with metered parking would increase empty VKT by 5.4%. We also present key performance metrics that are both temporally and spatially resolved, providing additional policy-relevant information. Simulation modeling is supplemented by expert interviews (n = 14) with practitioners, regulators, and policymakers in curbside management and innovative mobility to gain additional insight into policy considerations related to SAV curb access, staging, and parking.