3 research outputs found
Redesigning Large-Scale Multimodal Transit Networks with Shared Autonomous Mobility Services
Public transit systems have faced challenges and opportunities from emerging
Shared Autonomous Mobility Services (SAMS). This study addresses a city-scale
multimodal transit network design problem, with shared autonomous vehicles as
both transit feeders and a direct interzonal mode. The framework captures
spatial demand and modal characteristics, considers intermodal transfers and
express services, determines transit infrastructure investment and path flows,
and designs transit routes. A system-optimal multimodal transit network is
designed with minimum total door-to-door generalized costs of users and
operators, while satisfying existing transit origin-destination demand within a
pre-set infrastructure budget. Firstly, the geography, demand, and modes in
each clustered zone are characterized with continuous approximation. Afterward,
the decisions of network link investment and multimodal path flows in zonal
connection optimization are formulated as a minimum-cost multi-commodity
network flow (MCNF) problem and solved efficiently with a mixed-integer linear
programming (MILP) solver. Subsequently, the route generation problem is solved
by expanding the MCNF formulation to minimize intramodal transfers. To
demonstrate the framework efficiency, this study uses transit demand from the
Chicago metropolitan area to redesign a multimodal transit network. The
computational results present savings in travelers' journey time and operators'
costs, demonstrating the potential benefits of collaboration between multimodal
transit systems and SAMS.Comment: 44 pages, 15 figures, under review for the 25th International
Symposium on Transportation and Traffic Theory (ISTTT25