Demographic changes and shared-mobility technology have redefined the urban transportation fabric. Bike share, a public short-term bicycle rental program, has emerged around the world. Many users find bike share to be a convenient, healthy, and smart transportation option that solves first- and last-mile issues. But some are concerned that it may challenge existing rail transit systems and reduce ridership. Hence, it is important to understand the impacts of a bike share program on rail transit ridership.

The Washington metropolitan area lends itself well to studying this topic. Both the bike share and rail transit systems in this area, Capital Bikeshare (CaBi) and Metrorail, are the largest in the United States. According to the Washington Metropolitan Area Transit Authority (WMATA), which operates Metrorail service, CaBi services may challenge Metrorail ridership, especially for the short-distance trips. Based on WMATA’s concern, I explore whether CaBi substitutes for Metrorail and reduces its ridership.

An exploratory analysis finds evidence that CaBi can complement Metrorail trips in some cases and substitute for rail in others. To estimate CaBi’s impacts more precisely, three regression models—the Direct Ridership Model (DRM), the Difference-in-Difference (DID) model, and the Station-Specific Dummies (SSD) model—were applied.   

The results of the three models consistently demonstrate CaBi’s mixed impacts. CaBi may complement some Metrorail trips, but substitute for others, depending on the type and time. More importantly, the SSD results found that CaBi’s impacts vary by Metrorail station locations, whether a station is a downtown D.C. core station or a non-core station in peripheral and suburban communities. CaBi reduces core Metrorail station ridership by 4,814.4 per month for the number of AM peak exits and by 4,886.9 per month for the number of PM peak entries, but increases ridership at non-core stations by up to 2,781.2 per month, at a high statistical significance level. 

The finding that CaBi can complement Metrorail ridership is contrary to WMATA’s concern that a bike share program poses challenges for Metrorail. Policy suggestions are provided to help WMATA maximize the benefits of CaBi’s complementary effects.