Separated Bike Lanes Means Safer Streets, Study Says

A 13-year study of a dozen cities found that protected bike lanes led to a drastic decline in fatalities for all users of the road.

A protected bike lane in Seattle
A protected bike lane in Seattle

Cities that build protected lanes for cyclists end up with safer roads for people on bikes and people in cars and on foot, a new study of 12 large metropolises revealed Wednesday.

Researchers at the University of Colorado Denver and the University of New Mexico discovered cities with protected and separated bike lanes had 44 percent fewer deaths than the average city.

“Protected separated bike facilities was one of our biggest factors associated with lower fatalities and lower injuries for all road users,” study co-author Wesley Marshall, a University of Colorado Denver engineering professor, told Streetsblog. “If you’re going out of your way to make your city safe for a broader range of cyclists … we’re finding that it ends up being a safer city for everyone.”

Marshall and his team of researchers analyzed 17,000 fatalities and 77,000 severe injuries in cities including Denver, Portland, Dallas, Seattle, San Francisco, Kansas City and Chicago between 2000 and 2012. All had experienced an increase in cycling as they built more infrastructure. (Update: All of those cities also have varying rates of gentrification, which needed to be factored into the results, specifically because of “the safety disparities associated with gentrification.” Researchers said safety improvements in largely gentrified areas “suggest equity issues and the need for future research.”)

Researchers assumed that having more cyclists on the street was spurring drivers to slow down — a relic of a 2017 study that found that cities with high cycling rates had fewer traffic crashes. But it turned out that wasn’t the case.

Instead, researchers found that bike infrastructure, particularly physical barriers that separate bikes from speeding cars as opposed to shared or painted lanes, significantly lowered fatalities in cities that installed them.

After analyzing traffic crash data over a 13-year period in areas with separated bike lanes on city streets, researches estimated that having a protected bike facility in a city would result in 44 percent fewer deaths and 50 percent fewer serous injuries than an average city.

In Portland, where the population of bike commuters increased from 1.2 to 7 percent between 1990 and 2015, fatality rates fell 75 percent in the same period. Fatal crash rates dropped 60.6 percent in Seattle, 49.3 percent in San Francisco, 40.3 percent in Denver, and 38.2 percent in Chicago over the same period as cities added more protected and separated lanes as part of their Vision Zero plans.

“Bike facilities end up slowing cars down, even when a driver hits another driver, it’s less likely to be a fatality because it’s happening at a slower speed,” Marshall said.

Perhaps even more important: Researchers found that painted bike lanes provided no improvement on road safety. And their review earlier this year of shared roadways — where bike symbols are painted in the middle of a lane — revealed that it was actually safer to have no bike markings at all.

*We found they’re worse than nothing. You’re better off doing nothing,” Marshall said. “It gives people a false sense of security that’s a bike lane. it’s just a sign telling cyclists it might just be there.”

Not all protected bike lanes provide the same level of security for cyclists and drivers. In Denver, for instance, some protected lanes have plastic bollards that are interspersed along the roadway, allowing cars and trucks to park in the bike path and forcing cyclists to swerve into the street.

“When you have them designed like that, even if it’s a protected lane, that might create a more dangerous situation because cyclists are merging in and out of the road versus places with foot-wide concrete planters,” Marshall added.

New York was not included in this longitudinal study because the high number of cyclists and lanes would have overwhelmed their models, but will be a focus of a future study, Marshall said. New York’s Department of Transportation consistently touts how its protected bike lanes improve safety for all road users — but often denies neighborhoods the full protection of such infrastructure when some car owners complain of lost parking.

Sometimes, it’s not always “safety first.” 

21 thoughts on Separated Bike Lanes Means Safer Streets, Study Says

  1. How does this tally with the sharp increase in pedestrian/cyclist fatalities since 2015 in cities where most “protected” bike lanes have been built in the last four years?

  2. Study authors suggest no markings are best when protected lanes cannot be built. But those markings help cyclists after being hit in court, something that the study doesn’t address. The driver’s attorney always argues that the cyclist was negligent by riding there in that location. What a painted “sharrow” says is that the cyclist has a right to be there. This can help the cyclists beat back a claim that she was negligent.

    Sharrows should be painted on all lanes where protected lanes cannot be built for that reason alone.

  3. @Stephen Simac do you have a study to provide for that claim? im not inclined to believe an antivaxxer

  4. Edge: cycling is allowed on pretty much all surface streets, so that negligence argument is pretty piss-poor.

  5. @Edge Sharrows have been shown to decrease safety for cyclists and basically an abject failure.

  6. @Edge: yes, pavement markings might help in court AFTER THE FACT but do not help to prevent injuries.

    Hell, it might be cheaper for a DOT to simply give out free front and rear video recorders to cyclists. Then tell everyone that they’ve done this so they’d better behave.

  7. Protected bike lanes are an excellent idea along streets where few driveways exist, such as in central cities. But in suburbia, where driveways may exist every 50 feet, protected bike lanes only encourage cyclists to ride heedlessly through an unending series of these little intersections. It’s all very well to talk enthusiastically of protected bike lanes, but whether this advocacy is warranted depends entirely on the existing built environment.

  8. Concerned Citizen- when you know nothing about a subject, why bother bringing up another you know nothing about? Do your own research and come to your own conclusions. A simple search on Streetsblog will pull up the evidence I’m referring to. Cycling pedestrian deaths are spiking in the last four years, even in the cities that have installed the most “Protected” bike lanes, mostly in the last few years. You’re always welcome to debate the vaccination issue when it’s brought up, but first get your booster shots.

  9. The issue in many cities is that unprotected bike lanes are used for truck deliveries, cars lining up to turn into parking lots, people stopping to take a phone call or to text, police giving out traffic tickets, service vehicles, etc.. All illegal but impossible to ever hire enough police to enforce. Protected bike lanes don’t have to be the entire length of a bike lane but can be done strategically.

    It’s also amusing when someone claims that bicycle injuries or fatalities have gone up but they don’t factor in the increase in cycling that is caused by the new infrastructure.

    There’s also the issue of poorly designed protected bike lanes. In one eastern city, protected bike lanes increased cycling on that road by 75% but they did a two-way protected bike lane on a one-way street and they also didn’t really do proper protection. Bicycle injuries went up even more than the cycling levels, though in context were still low.

  10. I appreciate that protected bike lanes may make it easier, but they aren’t a replacement for enforcement. Reason I say this is because in Washington, DC where I live, I see even protected bike lanes used for truck deliveries, parked cars, etc.

  11. @Chris, if it’s possible to do deliveries or to park in a protected bike lane then they did a bad job in the design.

  12. I do drive to work daily and don’t bike but I strongly support the bike lanes (WHEN WE NEED THEM) Why can’t we come up with a solution so that we open up bike lanes for 5-6 months of the year during the warm months and convert them back into a full scale roadway in winter? There is no point of keeping them open and servicing them for those few cyclists who choose to bike during the winter period. I am sure that assembling and disassembling bike lanes (given we come up with a good solution) is more efficient than spending resources on cleaning them (and around them) in winter.

  13. Nick Streetsblog doesn’t have an easy way to search its stories as far as I can tell,(having attempted to do so on the SF site) but there have been numerous stories about the rise in bicycle and pedestrian fatalities over the last 3-4 years, both in Streetsblog and in numerous media and government reports. These are more easily searchable, so if you’re interested spend an hour confirming this. This fatality rise is national, but even cities that have built “protected” bike lanes (mostly in that same time period) have higher rates. Steven-pedestrians are also being killed at higher rates, are you suggesting there’s more walkers in the last few years? I don’t believe increased numbers of road users can account for all the increase, certainly not for pedestrians, and probably not for bicyclists, because only a few cities have seen a significant increase in riders.

  14. Nick, I read your linked story (thanks and I thought the readers comments showed how much conflict improperly designed and dangerously used bike lanes cause). I searched bicycle and pedestrian fatalities increase nationally and locally and found this well researched article. ( and a streetsblog story (…/walking-and-biking-are-hurt-by-lack-of-national-leaders…) I’m not contending that “protected” bike lanes increase fatalities, but noting that this national rise has been mirrored in cities that have built them, negating the conclusions of the study ending in 2012, when there were far fewer such lanes, because most lanes were simply painted lines until around then.

    yes there were 5 million matches, but these were on the first page.

  15. “Pedestrian and bicyclist fatalities increased by 32 percent in the ten-year period between 2008 and 2017. During that same time period, total traffic fatalities decreased by 0.8 percent” Steven- motor vehicle traffic also increased during that time, but their fatalities decreased. Even in the most bike friendly cities, or walkable communities user numbers did not increase by 32%, while nationally their numbers barely budged. So the cause is definitely more than user increase, while a few dozen miles of protected lanes can’t make much difference either.

  16. 60% of pedestrian deaths are the pedestrian’s own fault. Bring back individual responsibility and accountability.

  17. @Stephen Simac Absolute increases don’t paint an entire picture. How many more people are biking in these cities with better infrastructure? How many of those killed are killed while using protected lanes?

  18. Just a friendly reminder that Tom McCarey is a member of the National Motorists Association, an anti-accountability fringe group. Victim blaming is their thing, and they only believe in responsibility when it means people using cars can do whatever they like, regardless of the consequences.

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