The environmental benefits of demand-responsive transit and microtransit depend on the types of trips and vehicles they are replacing and generating. In theory, microtransit programs could pool passengers and thereby reduce emissions relative to drive-alone private vehicle trips [1], particularly if they use zero-emission vehicle technology. On-demand microtransit services tend to use vans that seat between four and twelve passengers. But empty vehicles [2], combined with vehicle miles lost to deadheading (trips with no passengers), can in some cases generate more emissions than private driving tips. Microtransit programs function as paratransit in some regions, and are notoriously expensive to provide in large part because they are often underutilized.

Demand responsive transit/microtransit programs in areas with limited public transit may offer a first- last-mile connection to transit, and thus enable less intensive car use. One study of suburban microtransit programs found that the majority of microtransit trips could not have been made with fixed-route public transit, and so microtransit largely either replaced ride-hail and private driving trips or generated new trips [3]. In particular, the study identified that microtransit induced trips among people without access to their own cars, and thus generated new vehicle miles traveled. More research is needed on the emissions and energy impacts of demand responsive transit and microtransit programs.