Bike Lanes

Special lanes for bicyclists can cause problems to the extent that they encourage bicyclists and motorists to violate the rules of the road for drivers of vehicles. Specifically, a bike lane continued to an intersection encourages right-turning motorists to stay in the left lane, not the right (bike) lane, in violation of the rule requiring right turns to be made from the lane closest to the curb. Similarly, straight-through, or even left-turning, bicyclists are encouraged to stay right. The photo below shows a bicyclist unlawfully making a left turn from a bike lane.

This bicyclist is turning left into the side street. He is making his turn from the bike lane, in violation of the rule requiring left-turners to merge to the center of the road before turning. He cannot safely yield to traffic ahead and traffic behind at the same time (location: North Beacon Street at Greenough Blvd, Watertown, Massachusetts, USA).

Bike lanes sometimes require bicyclists to violate normal traffic rules. For example, the bike lane pictured below, intended for straight-through bicyclists, is on the left side of a left-turn only lane. It is unsafe to go straight from this lane. However, use of this lane is mandatory in New York.

Why is this bicyclist stopped at a green light? To avoid a stream of cars turning from the left-turn only lane on the right of the bike lane. The dashed stripes indicate that cyclists are meant to continue straight from the bike lane. The cyclist in the rear is merging out of the bike lane so he can safely continue through the intersection — but this is illegal under New York law (location: Herald Square, New York City, USA).

Minimizing Bike Lane Confusion
Bike lanes cause less difficulty on roads without on-street parking and with few inter>sections. In that case they are essentially shoulders, except that they carry the legal or public expectation of mandatory use by bicyclists. Operational problems of bike lanes can be mitigating by insuring that bike lanes:

  • serve only one direction of traffic and be located adjacent to general traffic lanes, with no barrier separating the bike lane from the traffic lane;
  • are not marked adjacent to on-street parking unless the entire lane is more than 1 m (3 ft) from the edge of the cars;
  • are dropped within the last 30 m (100 ft) leading to an intersection, except that a short distance of bike lane to the left of a right-turn-only lane can be used, provided that there is merging space of 30 m (100 ft) with no bike lane stripes;
  • are not used inside roundabouts or add non-standard intersections where they lead bicyclists to the right of a right-turning lane.

Shoulders on high-speed, high-volume roads can be beneficial to bicyclists. Calling the shoulder a “bike lane” can make people think that the shoulder is the “bicycle facility,” when in fact the whole road is the bicycle facility. Although this public perception difficulty cannot be avoided when bike lanes are striped, it can be mitigated by:
• removing any legal obligations to use bike lanes;
• informing law enforcement and the public that bicyclists are not required to use bike lanes, just as buses are not required to use bus lanes.

Mandatory Bicycle Lane Use
Bicycle lane use is mandatory in the Netherlands, Denmark, Germany (if there is a bike lane sign), France (if required by local authorities), Ireland, and the U.S. States of Alabama, California, Florida, Hawaii, Maryland, New York, and Oregon (although Oregon adds, “A person is not required to comply with this section unless the state or local authority with jurisdiction over the roadway finds, after public hearing, that the bicycle lane or bicycle path is suitable for safe bicycle use at reasonable rates of speed”). Further, in jurisdictions that require bicyclists to operate generally as near to the right side of the roadway as practicable, marking a shoulder as a bike lane may create a greater restriction, since the shoulder is generally not part of the legal definition of “roadway,” but a bike lane is (except in Oregon, where a bike lane is not part of the “roadway”).

Studies of the Effects of Bike Lanes
Studies of bike lanes have established that:
• motorists give slightly less clearance when passing a cyclist in a bike lane compared to passing a cyclist in the same lane ;
• bicyclists position themselves on average in the middle of a 5 ft bike lane immediately adjacent to on-street parking, within reach of opening doors of parked cars (Hunter and Stewart 1999);
• bicyclists ride slightly further out from the curb where there is a bike lane or shoulder.
Only the last of these findings suggests a benefit to bike lanes, and that can be accomplished by striping a shoulder on higher speed roads. Many other studies have claimed to find safety benefits of bike lanes, but these compare bike lanes to sidepaths, not to ordinary roads, or look at special treatments to mitigate bike lane hazards, such as colored paint in conflict areas.

A study prepared for the US Federal Highway Administration claims that bike lanes reduce the incidence of sidewalk riding and stop sign violations (Hunter et al. 1999). However, this was not a before and after comparison of the same sites. The sites without bike lanes in the study had higher speeds (33% posted above 30 mph compared to 13%) heavier traffic (2/3 greater than 7,500 vehicles per day compared to 1/3), and less outside lane width (15 ft vs. 17 ft). Without controlling for these significant differences it is impossible to make a judgment about the effect of bike lanes themselves.

No study has shown that bike lanes improve safety. Since few car-bike collisions are the result of improper overtaking by motorists, it is not surprising that this is so. However, if there is increased danger from bike lanes, it is not large enough to show up clearly in the studies performed to date. The increased risk of sidepaths, on the other hand, is large enough to be consistently documented in many studies.

More Information and References
• John Allen on Barrier Bike Lanes.
• William W. Hunter et al. 1999. A Comparative Analysis of Bicycle Lanes vs. Wide Curb Lanes: Final Report (FHWA-RD-99-034). Full Report in PDF.
• William W. Hunter and J. Richard Stewart. 1999 An Evaluation of Bike Lanes Next to Motor Vehicle Parking (pdf)
• Wayne Pein, William W. Hunter, and J. Richard Stewart 1999. Evaluation of the Shared Use Arrow (pdf)
• Wayne Pein on bike lanes.


  1. The bicyclist in the photo is not on Charles River Road, but on North Beacon Street eastbound, turning left onto Greenough Boulevard. This location is particularly dangerous for a left turn from the right side of the road because the arched bridge (in the background of the photo) restricts sight lines. As it takes more time to cross from the right side, there is not time to yield to a motor vehicle coming across the bridge when turning left, other than by turning left in the vehicular style from the center of the roadway. See other examples of unsafe crossings at the same location at and the following two pages in my photo album.

  2. I believe bike lanes encourage use by less-experienced bicyclists, and therefore are to be encouraged generally. I don’t believe we have sufficiently developed the design of bike lanes, however, to account for all the potential dangers, such as the ones discussed on this page. Positive innovations must be developed and tested, such as the colorization of bike lanes, dotted-line lanes through intersections, etc. to advance the safety and usefulness of bicycle transportation.

    I don’t believe disappearing bike lanes at intersections is a such a positive innovation, however, as it appears to me to be a response to the legal liability faced by otherwise responsible municipal authorities.

    Let’s keep improving bike lanes to encourage use by bicyclists of all ages and abilities.

  3. Slight correction for your statement above “a bike lane should not be adjacent to on-street parking unless the entire lane is more than 1 m (3 ft) from the edge of the cars.” Since car door “stickout” can be slightly in excess of 4 feet, 3′ is not enough separation (although this is more than is usually provided).

    The comment by Jerry Foster is typical of “bicycle advocates.” He may as well have said “forget safety, cyclists are pawns and we need more of them.”

    A more responsible way to encourage cycling is to teach cyclists how to do it properly. This will enhance the safety, the effectiveness and the enjoyment of cycling. People taught properly will want to do it more.

  4. I like to give my 2 cent worth. The general bashing of bike lanes, is dated and result of some decades old designs. Much has been learned.

    In area of Sunnyvale, CA, newer bike lanes are marked and signed that near intersections cars are to merge into the wide bike lane to turn right. IN fact at Fremont Ave and Hwy 85 the bike lane is left of the right turn lane, where it should be.

    The real value of bike lanes is to segregate modes of traffic by their speed. In every state of the union, being picky it is unlawful to impede traffic, be you in a tractor, car or bike, if you have some many behind your vehicle (be it car, tractor or bike), you are to pull over. Bike lanes avoid that necessity. The safety issue for all is lane changes especially brought out with impatience cause all type of accidents, especially in cars and trucks blind spots, not just affecting bikers. Bike lanes of busy streets improves car traffic volume capacity.

    Another issue about bike lanes is in areas of high curb activity as in a commercial strip mall street, car drivers just do not notice someone in bike lanes. That is a street design issue, that perhaps some areas should not have bike lanes, till the street layout is fixed. If there is high curb activity, then speed limits, should be fairly low, 30 MPH, more conducive to taking the lane, and safer merging of cars into car traffic too..

    To claim that bike lanes are wrong and bad because local designs and driver familiarity is not up to date, or well thought out enough is folly. It leaves bikers with stone age facilities. In our area there are many excellent bike lanes, with very few curb entrances, designed well that right hooks are very rare on these well designed bike lanes.

    (frankly I have more concerns about right hooks even taking the lane with impatient drivers on some 6 lane streets without bike lanes we have here – for those bad drivers the only solution is for all bikers to get their tag numbers and call the police, our police are very good in talking with those who drive unsafely, it seem to work for the most part.)

    The best resource on appropriate deign of bike lanes I have seen so far (there are likely better ones) is the London Cycling Design Standards

    P Grant Sunnyvale ,CA, USA

  5. Hi

    You say: “The UK has both advisory cycle lanes (use not required) and compulsory cycle lanes (use required)”. This is incorrect.

    With mandatory (not compulsory) cycle lanes it is mandatory for motor vehicle to keep out of the lane – not for cyclists to use them. Mandatory cycle lanes are marked by solid lines.

    Advisory cycle lanes are marked by dashed lines and motor vehicles can enter them if a cyclist in not in them.

    In the UK it is not compulsory for cyclists to use any cycle facilities such as cycle lanes. Cyclists have the right to use any road (except motorways).

    Hope this helps.


  6. I think there should be more public awareness concerning bikes and cars. I see more and more bikes in the “left turn lane” along with the cars. Some of these people will even be in the center of the lane as if they were driving a motor vehicle. If the law allows this, than it should be known. In Southern California is happens quite often. I have to watch for motorcycles, now I have to be aware of “Bikes”. I think they should stay in the bike lane. “BANC” Bikes are not cars!!!

  7. Hi Tony, I agree there needs to be more awareness that bicycle drivers generally have the same rights and responsibilities as motor vehicle drivers. That includes turning left from the left turn lane, for example. Or having the right to use an entire lane, if it’s too narrow to share with another driver.

    All drivers should be watching for all other drivers, regardless of vehicle type. That’s much easier if all drivers are following the same rules.

  8. Bicycles are recognized in all 50 states as a legal vehicle. Yes, more education is needed to make ALL road users aware of this fact.

    When I started commuting, I used the sidewalk. Bicycle lanes were used, when available, but mostly sidewalks. I did not feel comfortable using either or “safe” for that matter.

    Most bike lanes in Orlando, FL serve as a trap for debris swept from the travel lanes or storm runoff. I would be better off taking the grassy right of way than to use the bike lanes we have.

    My story:

  9. Paul,

    I seem to recall coming across a comment you made that Somerville MA has made bike lane use mandatory, but I can’t find it.

    Is this true – does Sommerville have a MBL law?
    Are there any exceptions at all (left turns, bike lane blocked, etc.)?
    Where have they installed bike lanes?
    How well/poorly are they installed?
    Does Massachusetts let local towns impose any arbitrary restriction on bicyclists they choose?

  10. Somerville’s traffic regulations ( include the following adopted in 2006:

    “Section 13-7 Lane Use in Designated Bicycle Lanes
    Not withstanding the provisions of Section 13-6, bicyclists shall yield the right-of-way to motorists making a right turn maneuver in a bicycle lane. Except when overtaking a slower
    bicyclist or to make a left turn maneuver, or to avoid a hazard, bicyclists shall stay within marked bicycle lanes. When making a left turn maneuver, bicyclists shall move to the center of
    the roadway and execute their maneuver in accordance with the rules of the road. Bicycles shall be operated consistent with the provisions of c. 85 of the General Laws.”

    Lot’s of problems here. Despite the last sentence, it’s clearly inconsistent with state law, and therefore invalid. However, some day it might cost someone a lot of time and legal fees to find this out. Meanwhile, it’s a license for harassment.

  11. Tony, *you* need to be more aware about bikes and cars. You do have one thing right, though: BANC. Vehicles on the road (cars, tractors, bikes, whatever) need to follow the rules of the road. E.g. slower traffic keep right; make left turns from the the left-most lane; when making a left turn, yield to oncoming traffic; It doesn’t matter what type of vehicle you are, you might have to wait in a left turn lane at some point in your ride/drive.

  12. It’s important to note that most states in the USA allow for cyclist to control the entire lane when it is of insufficient width for a motor vehicle and bicycle to occupy side by side in a safe manner. In most states this width is fourteen feet.

    The concept that slower traffic should keep right does not apply to traffic in a single lane. Slower traffic keeping right applies to interstate roadways on which bicycle traffic is not permitted other than in rare exceptional cases. Surface traffic is not subject to slow-traffic-keep-right consideration because people turn left on roadways without dedicated left turn lanes.

    Bikes are not cars, but bicycles are vehicles with the same right to the use of the roadway as other vehicles, except in states (one or two) in which they are not classified as vehicles. I’m glad I don’t live in one of those states!

  13. Tony was commenting on bicycles in the left turn lane as if they were cars. In Ontario, slower traffic keeps right on all multilane streets and highways. The left lane is a passing lane (this doesn’t always happen, but that’s the rule). Through traffic, however, would not drive in a right turn lane in order to “keep right”. When there is no left turn lane, left turns are made from the left-most lane (in single lane traffic, that would be the lane – that’s what “left-most” means).

    I for one ride primarily in the right lane. When making a left turn at a large intersection with more one left turn lane, I choose the outside left turn lane as it will be much easier to get back to the right lane after making the turn.

    Happy and safe riding everyone!

  14. I bike everywhere in this city but avoid busy streets. There’s enough secondary(?) streets that parallel the busy ones that its just as fast to bike them. Even if its a bit slower, I feel safer.

    I like bike lanes, but only the type on the street. Sometimes catwalks and bike trails let you take a shortcut, so they are handy too. I don’t like bike paths up beside the sidewalk cause they have many of the same hazards for fast moving cyclists as sidewalks, drivers on the road tend to treat them like pedestrians instead of vehicles, and you have to use the crosswalks to make left turns and cross intersections and your supposed to walk a bike through crosswalks.

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