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Study says bike lanes really work

Are bike lanes a good idea or bad? On the one hand, they let cyclists ride in the road without blocking cars that might get impatient, honk, and even drive into cyclists. They clearly delineate that this space is for cycling, and make cyclists feel more comfortable. On the other hand, cars and trucks often don't expect cyclists, and turn across the lane without looking, sometimes creating tragedy. Drivers often block the lanes. Is it better for bikes to drive in the regular lane, or on dedicated bike lanes?

Photo by M.V. Jantzen on Flickr.

Portland researcher Jennifer Dill believes bike lanes are better, and has hard numbers to back it up. According to Dill's survey, which tracked 164 bicyclists for a week via GPS, most cyclists go out of their way to use bike lanes. They used the lanes for 51% of trips on the lanes even though only 8% of roads have such lanes.

Of course, just because people choose to use the lanes doesn't prove they are better or safer. But Dill found a psychological effect as well with a big gender gap. According to the article, "Women are far more reluctant than men to ride a bicycle in heavy motor vehicle traffic," with 52% of women citing traffic as an obstacle to more cycling, while only 34% of men wouldn't ride because of traffic.

Whether collisions in bike lanes are more numerous or worse than collisions outside bike lanes, there's clear evidence that lanes make more people feel safer riding. And the more people ride, the safer it is, because drivers become accustomed to seeing and avoiding cyclists. This study won't settle the ongoing debate, but it provides one more piece of evidence that more bike lanes are better for everyone.

David Alpert is the founder of Greater Greater Washington and its board president. He worked as a Product Manager for Google for six years and has lived in the Boston, San Francisco, and New York metro areas in addition to Washington, DC. He now lives with his wife and two children in Dupont Circle. 


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I've come to see bike lanes as something of a feeder system. They get people comfortable riding next to/sorta in traffic, and as these people become more confident cyclists, they'll move away from the bike lanes.

Works for me.

by MB on Oct 20, 2008 11:35 am • linkreport

Has any city tried putting up those little plastic rods along the bike lanes to better identify the lane to the drivers? Spacing them out every 30 feet or so would create the right visual effect without blocking cars from crossing the lane when they need to (to parallel park, for instance) or creating too much visual clutter.

by Reid on Oct 20, 2008 11:45 am • linkreport

I agree that bike lanes are a good thing, and I do seek them out and use them when I find them.

However, I think something that would help out would be for there to be periodic cycling instruction in elementary and middle schools, culminating with issuing a non-mandatory "bicycle license" to students that learned the curriculum.

Combine that with real lessons on driving safely around cyclists as well as cycling safely around cars during driver's ed and backed up with questions on the exam and you've gone a long way toward legitimizing road cycling, which is half the battle (I think the other half is driver/cyclist inattention).

by Michael Perkins on Oct 20, 2008 12:08 pm • linkreport

Because people feel safer in bike lanes maybe part of the reason for the number of accidents. I think this may be a demonstration of the "Peltzman effect".

by Tom on Oct 20, 2008 12:18 pm • linkreport

David "Whether collisions in bike lanes are more numerous or worse than collisions outside bike lanes, there's clear evidence that lanes make more people feel safer riding. And the more people ride, the safer it is, because drivers become accustomed to seeing and avoiding cyclists."

That's circular logic ... at best. The same argument could be used to "prove" that bike lanes make biking in the city more dangerous because there are more people out there riding around with a false sense of security.

Actually, using your logic a real argument could be made that once there is a critical mass of riders out there impeding vehicular traffic, there will be a general backlash and cyclists will be banned from more than just the Interstates.

by Lance on Oct 20, 2008 12:33 pm • linkreport

Peltzman effects and increased ridership aside, it seems like a stretch of logic to argue that bike lanes make things worse for cyclists. It's just like the adage that good fences make good neighbors. Carving up the road for bike and auto use is smart policy.

One caveat is that you need to place and stripe the lanes intelligently. Broken lane lines for areas where cars can pull over for turns. No bike/bus lanes like they have on 7th and 9th streets northwest. Those are death traps, with cyclists playing frogger with the buses and the many weaving scofflaw motorists who can't pass up a car-sized empty lane while they wait in traffic.

by Ward 1 Guy on Oct 20, 2008 1:10 pm • linkreport

I'm a big fan of DC's bike lanes and I use them as much as possible. I do think that they are safer overall. I still don't understand the minority of drivers who insist on riding 1/2 to 2/3 into the bike lane when everyone else in front of and behind them are in the correct lane. I've been known to tap them on the hood or side as I go by. I think as time goes on and more bicyclists use the lanes regularly, drivers will be more accustomed to seeing them and actually stay out of the bike lanes.

by Matt on Oct 20, 2008 1:24 pm • linkreport

Matt, I think only more enforcement will work to keep the bike lane reserved to bikes. One problem though is that the reason you're seeing cars in that lane now is that most drivers (or even the District officials who allowed the bike lanes to go in, I'd bet) don't realize fully what the bike lanes mean from the viewpoint of cyclists (i.e., that cars shouldn't be going into them under any circumstances other than where there are broken lines.) From talking with motorists the solid lines are generally not viewed as "uncrossable" by them. And from a logical/practical standpoint that makes a lot of sense. If you are not a motorist, you might not realize that if traffic cannot ever cross these solid lines than it cannot avoid a parked (or stopped or turning) car on the non-bike lane side of the road; it cannot cross the line to park in parking spaces that lie on the other side of the bike lane; it cannot stop on the bike lane to drop off/pick up elderly/children/heavy packages; it cannot do a lot of the things that let traffic circulate in a normal way. I'd bet a lot of the folks who allowed the bike lanes to be installed didn't quite think through the impact uncrossable lanes will have on vehicular and pedestrian traffic in a myriad of ways. And I'd bet once it does realize the impact (i.e., once strict enforcement starts), you'll find immense pressures from the motorist/pedestrian majority to change things.

by Lance on Oct 20, 2008 1:40 pm • linkreport

I think Reid is on to something, for straight roads.

Rubber/plastic barriers (which 'slap' your car without denting it) would prevent the sliding out of the lane & into the bike lane that occurs as a safety-focused instinct in a minority of drivers.

by Squalish on Oct 20, 2008 4:44 pm • linkreport

Experience in the Netherlands shows that bike lanes are safer, just because cars tend not to venture into them as much. However, painting them in a different color (red in stead of asphalt black) makes the psychological barrier even larger. It is best though to have a physical separation between cars and bikers.

If you want their data, just give 'm a call, and I am sure they'll be happy to send you a bunch of paperwork.

They even have a website in English, so I am sure they'll have some info in English as well (they probably need to, to be able to send stuff to the EU).

by Jasper on Oct 21, 2008 9:15 am • linkreport

In many parts of Germany, bike lanes are built not on the street, but on the sidewalk. In such cases, they are often recessed and inch or two lower than the sidewalk, and separated from both the street and the sidewalk by a curb. (they also tend to have their own crossing lights). Usually the lane is situated between the sidewalk and the parking lane.

While this requires a much larger investment than simply painting stripes on a road, it also avoids a number of problems. In particular, cars can't park in the bike lane, buses don't need to straddle the lane at bus stops, and bicyclists are in a much more predictable place for cars making right turns.

The one place I have seen this in use around DC is on Wayne Ave in Silver Spring, between the Metro and Whole Foods. It's not grade separated, but it is demarcated clearly by a different color of brick and asphalt. I think this sort of thing should be done everywhere. :-)

by Andrew on Oct 21, 2008 1:41 pm • linkreport

What about experiment with putting in the center of the road, with those little plastic barriers? Yes, it would separate the double-yellow line, but a)the driver can see the cyclist before making a left turn, b)it is possible to put up those aforementioned little barriers without annoying parkers, c) cars pulling out of the curb lane avoid sending cyclists into the air.

by Adam on Oct 24, 2008 10:13 pm • linkreport

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