Constructing a routable multimodal, multi-cost, time-dependent network model with all emerging mobility options: Methodology and case studies

Abstract

Cities aiming to improve their transportation networks are integrating emerging mobility options at a rapid pace. These modes provide commuters with greater flexibility to construct more convenient trips and reach a larger set of essential service destinations. A few open-source tools allow planners to conduct multimodal routing analysis in time-dependent networks, but they do not sufficiently capture the full set of travel mode combinations and disutility factors perceived by individual travelers. To this end, we introduce NOMAD: Network Optimization for Multimodal Accessibility Decision-making. NOMAD integrates the personal vehicle, transportation network company, carshare, public transit, personal bike, bikeshare, scooter, walking, and feeder micro-transit modes into a unified routable network model. A generalized travel cost function incorporates the following disutility factors: monetary cost, day-to-day mean travel time, (un)reliability as represented by day-to-day 95th percentile travel time, crash risk, and physical discomfort. The proposed open-source tool can be used to create multimodal travel cost matrices, which may immediately serve as an input for accessibility analysis and other policy decisions related to emerging mobility options. This paper develops the network model that forms the basis of NOMAD and demonstrates four use cases in Pittsburgh, PA.