Micromobility services (e.g., bike share, e-bike share, e-scooter share) are often considered good options for reducing vehicle miles traveled (VMT) and related greenhouse emissions. The expected benefit of using micromobility services assumes that most users substitute bike and scooter trips for personal car and ride-hailing trips. If a major mode shift comes from other sustainable transportation options like walking and bicycling, the benefits of micromobility services may be more limited. The researchers’ prior studies show that micromobility users substitute micromobility services for car use and occasionally use the services to connect to transit at the trip level. These substitution and connection effects are important for estimating the overall environmental sustainability of micromobility services. However, quantifying metrics to monitor the impact of micromobility services on travel behavior change and transportation emissions is a challenge. Data on transit connections either requires integrated payment systems or invasive travel behavior data collection (e.g., Global Positioning System(GPS) travel diaries), and because travel mode substitution is inherently counterfactual in nature, estimating sustainability metrics from counterfactual survey responses raises numerous validity concerns. Since it is not feasible to conduct a randomly controlled trial of the effects of micromobility services on travel behavior, to estimate valid metrics, triangulation (convergence) of multiple metrics is likely the most prudent approach.
In this project, the research team will quantify the magnitude of micromobility service effects on vehicle miles of travel (VMT) through triangulation and synthesis of three primary travel behaviors: mode substitution, transit connection, and driving/ride-hailing behavior. The team will also explore the factors that lead to greater VMT reduction within micromobility services, what the barriers and accelerators are for people to use micromobility services (particularly as a car replacement), and what these factors mean for planning and policy as micromobility services continue to rapidly change in terms of vehicle form, application (app) design, and monitoring technology.
