Which Matters More — A Bike Network’s Connectivity or Its Density?

The "connectivity" of bike infrastructure a city has matters, but not as much as some other aspects. Image: University of Minnesota
Adding to total bike lane mileage without creating a denser network does not seem to affect ridership. Image: University of Minnesota

What’s the secret to designing a bicycle network that will get people riding?

A pair of researchers at the University of Minnesota recently set out to test the theory that a connected bike network — where bike lanes provide continuous routes between many possible destinations — is a major determinant of how many people bike. What they actually found was a little unexpected. Connected bike infrastructure matters, according to the study [PDF], but not as much as the density of bike infrastructure.

UMN’s Jessica Schoner and David Levinson used GIS software to map cities’ bike networks and rank them according to connectivity, size, density, and other factors. (“Connectivity” is basically a measure of the degree to which bike lanes intersect within a city, and “density” is a measure of bike lane mileage within a given area.) Then, using Census data, they determined the relationship between each factor and the number of people who commute by bike.

Bike lane density was the most important factor, with each standard deviation (about 1 kilometer of bike infrastructure per square kilometer) associated with an additional 150 bike commuters per 10,000 commuters. For connectivity, one standard deviation correlated to an additional 37 bike commuters. Other factors — the overall size of the bike network, the directness of routes within the system, and fragmentation (separate clusters of bike lanes within the same city) — were not shown to have a statistically significant effect.

Schoner and Levinson caution that correlation does not equal causation, so it’s unclear whether the dense networks enticed more people to bike, or if higher numbers of cyclists helped create denser bike networks. The study also did not distinguish between protected bike lanes, painted bike lanes, and off-street paths, so it does not account for the degree of separation between cyclists and traffic.

But the study does indicate that the density of bike lanes within a city could be an under-appreciated factor in getting more people to ride. “These findings suggest that cities hoping to maximize the impacts of their bicycle infrastructure investments should first consider densifying their bicycle network before expanding its breadth,” the authors concluded.

ALSO ON STREETSBLOG

There’s Safety in (Bike-Specific) Infrastructure

|
Today on the Streetsblog Network, Bike Portland looks at a new review of the scientific literature on the relation between bicycle infrastructure and injuries to cyclists, conducted by researchers at the University of British Columbia. While the study points up the need for more data, it finds that dedicated bicycle infrastructure is associated with a […]

Bike Infrastructure Where You Live

|
This path on New York’s Randall’s Island gives cyclists plenty of space. (Photo: Bicycles Only) Get ready for another Streetsblog Network slide show. This time, in honor of National Bike Month, we’re looking for pictures of bicycle infrastructure that you love. Lanes, trails, paths, signs, signals, parking, you name it — we want to see […]

Bike Infrastructure Where You Live

|
This path on New York’s Randall’s Island gives cyclists plenty of space. (Photo: Bicycles Only) Get ready for another Streetsblog Network slide show. This time, in honor of National Bike Month, we’re looking for pictures of bicycle infrastructure that you love. Lanes, trails, paths, signs, signals, parking, you name it — we want to see […]

Bike and Ped Infrastructure Depends on Federal Funds, Too

|
With all the kerfuffle in Washington right now over the federal transportation law and the crisis in the Highway Trust Fund, it seems like an appropriate time to be reminded of the role that federal dollars play in funding bicycle infrastructure. Today, Streetsblog Network member DC Bicycle Transportation Examiner has a post doing exactly that: […]