Measuring bike traffic increases after infrastructure installation

By Sam Sklar

A recently released report from the City of St. Paul, MN, noted a jump in observed bicycle use after installation of bike lanes. This observation suggests that upgrading or adding infrastructure for bikes has a positive impact on attracting new riders. Other cities have similarly found that mode split and overall bicycle use numbers collected before and after infrastructure investments show important changes to both the safety of the corridor and willingness to use the street for active transportation.

St. Paul measured five locations before and after bike lane projects, and found that all five had at least a 63 percent growth rate, with the largest increase at the intersection on the south side of Cleveland Avenue and Marshall Avenue— an increase of 160 percent between 2014 and 2017.

Intersection of Cleveland and Marshall Aves, 2014 (Source: Google Earth)

Intersection of Cleveland and Marshall Aves, 2017 (Source: Google Earth)

The two images above show before (left) and after (right) treatment. By removing a strip of parking along Cleveland Avenue, and replacing it with a bike lane, St. Paul was able to provide a more comfortable biking environment that didn’t require sharing the lane with cars, using the sidewalk, or even any parallel route options.
St. Paul is not the only city to notice an increase in biking and walking as a result of new infrastructure that reconfigures the street to be more equitable and comfortable for all modes of transportation. The City of Oakland noticed a similar effect on Telegraph Avenue, between 20th and 29th Streets.
The Intersection of Telegraph Avenue and 20th Street, before (9/2015), during (10/2015), and after (3/2017) (Source: Google Earth)

After Telegraph Avenue underwent a reallocation of the right-of-way, the city documented the effects, which included an increase of 70 bike trips compared to a decrease of 150 car trips between 2014 and 2017.
In a peer reviewed study in the Journal of Physical Activity and Health Professor Barbara Brown at the University of Utah documented the effects of infrastructure investment in Salt Lake City, UT. Her statistical findings are consistent with the changes found in St. Paul’s report and Oakland’s plan update, and show that infrastructure changes affect more than travel patterns. She found “[…] the increased active travel after the community intervention [was] consistent with the idea that complete streets can encourage more active transportation and should not be considered just a transportation intervention but a potential health benefit to communities (Brown et. al. 2016).”
Finally, the City of Boston released a memo a few weeks ago that summarized an intervention at the intersection of Washington Street and Blue Ledge Drive. While bicycle activity remained relatively low, the memo noted that this is due in part to the fact that, despite the addition of bike lanes, this intersection is not connected to a larger bicycle infrastructure system. But the infrastructure provided the means for fewer bicycles to travel along the sidewalk: reduction to 14 percent after the lanes were added versus 25 percent before. In an area with limited bike transportation, the fact that Boston measured bicycling and analyzed the results of the infrastructure changes gives the city an example for project development in a similarly constrained location. The improvement in safety and comfort was documented for both bicyclists and pedestrians rather than for a total number of users. This type of measurement, while less obviously quantitative, is nevertheless essential to measure.
Intersection of Washington Street and Blue Ledge Drive, Before (Source: City of Boston)

Intersection of Washington Street and Blue Ledge Drive, After (Source: City of Boston)

What makes these examples compelling is the focus on data collection before and after the infrastructure investment and street reconfiguration. Understanding to what extent an investment alters bike usage and mode split in the corridor allows planners and engineers to make a stronger case for similar projects in the future and helps to demonstrate simple and tangible results to taxpayers. And conversely, it is difficult to demonstrate meaningful bike safety and capacity impacts of projects without robust, consistent, and accurate data collection.
Sam Sklar is a Program Associate at SSTI.