May 10, 2017

Kayleigh Campbell, who will graduate next week from SIPA’s PhD Program in Sustainable Development, has published a paper on the relationship between bikesharing and bus ridership. The paper, which was written with Candace Brakewood, an assistant professor of civil engineering at City College of New York, appeared in the June 2017 issue of the academic journal Transportation Research Part A: Policy and Practice, and was featured in Atlantic Media’s CityLab website.

The objective of the research, the authors wrote, is to quantify the impact that bikesharing systems have on bus ridership. In addition to finding a 2.42 percent decrease in bus trips as a result of bikesharing (via the CitiBike network) near bus routes in New York City, Campbell and Brakewood found that people who are not bikeshare members may also be changing their travel behavior. (See complete abstract below.)

Interpreting the findings for SIPA News, Campbell said the high visibility of bikesharing could be helping to change the way people think about bicycling in general, prompting more bicycle rides both inside and outside the bikesharing network.

In their conclusion, the authors write that “We hope that a better understanding of the relationship between these two different modes encourages agencies who traditionally operate separately to create more integrated systems that support the reality of multimodal, shared transportation systems.”

Campbell will begin consulting for the World Bank’s Development Impact Evaluation group soon after graduating. Among other things she will help manage 22 different impact evaluations in the transport and ICT sector.

“I will miss teaching,” she told SIPA News, “but this position is a wonderful opportunity. It's a great match for me since I'll be working between the research and operational teams.  They’re doing so much, and it’s a great chance to access these types of projects.”


The objective of this research is to quantify the impact that bikesharing systems have on bus ridership. We exploit a natural experiment of the phased implementation of a bikesharing system to different areas of New York City. This allows us to use a difference-in-differences identification strategy. We divide bus routes into control and treatment groups based on if they are located in areas that received bikesharing infrastructure or not. We find a significant decrease in bus ridership on treated routes compared to control routes that coincides with the implementation of the bikesharing system in New York City. The results from our preferred model indicate that every thousand bikesharing docks along a bus route is associated with a 2.42% fall in daily unlinked bus trips on routes in Manhattan and Brooklyn. A second model that also controls for the expansion of bike lanes during this time suggests that the decrease in bus ridership attributable to bikesharing infrastructure alone may be smaller (a 1.69% fall in daily unlinked bus trips). Although the magnitude of the reduction is a small proportion of total bus trips, these findings indicate that either a large proportion of overall bikeshare members are substituting bikesharing for bus trips or that bikesharing may have impacted the travel behavior of non-members, such as private bicyclists. Understanding how bikesharing and public transit systems are interrelated is vital for planning a mutually reinforcing sustainable transport network.

Read the complete paper

Additional coverage: CCNY News

Pictured: Kayleigh Campbell // photo courtesy Kayleigh Campbell