Equity Impacts of Public Transit Network Redesign with Shared Autonomous Mobility Services

TL;DR

This paper investigates how integrating shared autonomous mobility services into transit redesign can improve equity in access, especially for underserved and vulnerable populations, using Chicago as a case study.

Contribution

It compares equity-focused and equity-agnostic transit network redesign strategies incorporating SAMS, highlighting their impacts on accessibility and equity.

Findings

SAMS reduces transit access gaps across zones.

Equity-focused redesign improves access for underserved populations.

Suburban and city areas benefit differently from SAMS integration.

Abstract

This study examines the equity impacts of integrating shared autonomous mobility services (SAMS) into transit system redesign. Using the Greater Chicago area as a case study, we compare two optimization objectives in multimodal transit network redesign: minimizing total generalized costs (equity-agnostic) versus prioritizing service in low-income areas (equity-focused). We evaluate the achieved accessibility of clustered zones with redesigned transit networks under two objectives, compared to driving and the existing transit network. The transit access gaps across zones and between transit and driving are found to be generally reduced with the introduction of SAMS, but less so with the subsequent improved infrastructure under budget. Differential improvement in equity is seen across suburbs and areas of the city, reflecting the disparity in current transit access and improvement potential. In particular, SAMS bridges the transit access gaps in suburban and city areas currently underserved by transit. The City of Chicago, which is also disproportionately home to vulnerable populations, offers an avenue to improve vertical equity. These findings demonstrate that SAMS can enhance both horizontal and vertical equity in transit systems, particularly when equity is explicitly incorporated into the design objective.