Bike share both reduces use of other modes and induces new trip-making

By Eric Sundquist

The transportation literature on mode choice is robust, though not complete. One emerging issue is the bike share system, a mode that is not only new to the scene, but one that is purposely designed to work in concert with other modes as a first- or final-mile solution.

Fortunately, the Capital Bikeshare system, which opened in 2010 in and around Washington, has made a particular effort to gather and analyze travel data. The system gathers both mechanically- tracked information on usage and survey-generated information on users.

Evidence on mode choice comes from the latter. It is intuitive to suspect that the emergence of a new mode would both substitute for other modes and induce new travel. And that is what the Capital Bikeshare survey finds.

As a substitute, the Capital Bikeshare members reduced driving, walking and transit use. The report estimates the VMT reduction at an average of 198 miles per year per member, or 4.4 million annually for the 22,200-strong membership as a whole. About half of that reduction comes in reduced driving for work. According to the survey, 5 percent of the members sold a car, or one of their household’s cars, after joining.

The report did not similarly quantify reductions in the use of other modes. It points out that more than half of the members used bike share to come from or go to a transit stop in the previous month, indicating a strong link between these modes. Overall transit use among members fell, however, as bike use was substituted for some generally short bus or train rides.

The survey indicated that members saved an average of $800 a year by making these changes.

Capital Bikeshare also induced some travel, according to the survey. Forty percent of respondents reported at least one trip that they would not have taken otherwise in the month before the survey. Most of these trips were for non-work purposes.

The survey was conducted in November 2012. The analysis is based on 3,731 responses.

Eric Sundquist is Managing Director of SSTI.