Traffic Speeds Under 20 MPH Make Cyclists Feel Safe to Bike to Work, Study Finds

A new study finds that after hills, speeding traffic is what scares cyclists.

Commuters on bikes in London
Commuters on bikes in London.

Dan Kitwood/Getty Images

While a Daily Mail contributor complains in an unhinged rant that "transport policy has been captured by single-issue, anti-car fanatics, hell-bent on bankrupting businesses and causing the maximum possible inconvenience to the travelling public," The Times of London reports that in some parts of Britain, bikes outnumber cars. Duncan Dollimore, head of campaigns at Cycling UK, told The Times:

“London shows that when you start to build a network, and not just individual schemes, you see increased levels of cycling across the whole network or town or city,” he said. “We are seeing similar increases in pockets across the rest of the country where there is a commitment to separated space. People will cycle if the conditions feel safer.”

A new study from the University of Surrey confirms more people bike when they feel safer on the roads. Surrey is a district covering 656 square miles (1,700 square kilometers) with 1.1 million inhabitants and a few separated bike paths along key commuting routes. The study examined riders doing short commutes under three miles on 35,000 different routes.

Andy singer cartoon

Andy Singer

The study found hills were the biggest impediment and "the findings show that a commuter is more likely to travel by bicycle if their shortest route to work has a greater proportion of separated cycle paths." However, cyclists did not tend to go out of their way for cycle paths, and generally took the shortest path to their destination. This reminded me of that great Andy Singer cartoon that pointed out that everyone wants a straight line.

But after hills, the biggest impediment was the speed of traffic. Surprisingly, large numbers of trucks did not seem to be a bother and busy streets were less of a concern. In fact, cyclists actually seemed to like busy streets. "It may even be a reflection of the enjoyable sensation experienced by cyclists as they pass stationary traffic—motivating those commuters concerned with arriving at work on time and providing reaffirmation they have made the right choice by cycling," reads the study.

The researchers conclude:

"Above-average traffic speeds along the cycling route are shown to be the dominant traffic-related factor deterring commuters from cycling to work. Above-average traffic volumes in combination with above-average traffic speeds across the route also act as a noticeable deterrent. The results suggest that 30 km/h [20 MPH] zones would be beneficial in encouraging commuter cycling levels, even in congested areas. Since traffic speeds are found to be particularly discouraging for female commuters, low-speed zoning may also help redress some of the gender imbalance in commuter cycling levels."

The study also concludes the design of intersections is important: "Consideration of how cyclists interact with traffic at junctions should continue to be a focus for transport planners. This study emphasizes that well-designed junctions may be just as important as dedicated cycling infrastructure."

Dr. Susan Hughes, one of the researchers, is quoted in the University of Surrey press release, noting that the Daily Mail types might not like these conclusions.

“Cutting speeds may be unpopular with drivers, but our research shows it does encourage people onto their bikes. It’s a change which, if implemented strategically, may encourage more people to cycle, with the added benefit on people’s health from reduced carbon emissions. Hence, there are opportunities to make towns more attractive to cyclists.”

Twenty miles per hour speed limits are unpopular with drivers everywhere, but they are spreading. Paris recently imposed them, and drivers complained that "it's one of those tiny, slightly stupid measures, that means French people are sick of politics," even though it cuts pedestrian deaths in half. London has a 20 mph limit for much of the city. Toronto is rolling out lower speed limits and noted that it doesn't significantly affect travel times:

"Studies have shown travel time is more dependent on congestion, roadway design and geometry factors than on the posted speed limits. Under medium congestion levels (where traffic is periodically able to travel at or near the speed limit), a lower speed limit may actually reduce overall travel time by allowing a smoother traffic rhythm because lower speeds reduce safe space required between vehicles."

Back in the Daily Mail, our curmudgeon columnist rages against the politicians who are making their cities safer for cyclists, calling them "polar-bear huggers in thrall to the cult of the great god cycling."

But all over the world, people are getting the message that getting people out of cars and onto bikes and e-bikes reduces carbon emissions quickly and inexpensively. The 20's Plenty for Us and Streets for Life groups have known for years that lowering speed limits saves the lives of people walking and biking; Now the University of Surrey research demonstrates it makes a big difference in peoples' willingness to ride. It's time to make 20 mph the speed limit in cities everywhere.

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