National Center for Sustainable Transportation

Ride-hailing services, which allow consumers to order and pay for rides through smart phone applications, have grown to a substantial proportion of the transportation market. Today, an estimated 15% of adults across the U.S. and 21% living in major U.S. cities have used ride-hailing services. The growth of ride-hailing services has raised questions about their overall effects on the transportation system. While they clearly offer a new form of mobility, there is concern they may increase congestion and air pollutant emissions. A limited number of studies have attempted to quanitfy changes associated with the increased use of ride hailing services.

UC Davis researchers examined how ride-hailing affects the total amount of driving (measured in vehicle miles traveled, VMT) as well as greenhouse gas (GHG) emissions. The researchers developed a framework of categories for analyzing the multiple aspects of transportation that may be affected by ride-hailing. These categories are: automobile ownership; number of vehicle trips generated; choice of mode of travel; empty (passenger-less) travel between drop-off and pick-up points, known as “network travel”; and destination choice and land use. Thirteen (13) studies were analyzed using this new framework: 8 used surveys of riders or recorded data on rider and driver activity; and 5 used simulated (“modeled”) travel in and around cities by automated taxis. By compiling multiple studies in the framework, stronger and more certain conclusions could be reached.

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