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: Charles River Road, 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 completely unsafe to go straight from this lane. However, use of this lane is mandatory in New York.
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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 Harm
Bike lanes cause less harm on roads without on-street parking and with few intersections. 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 observing the following requirements:
• a bike lane must 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;
• 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;
• a bike lane should not be striped 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.
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 political problem cannot be avoided when bike lanes are striped, political problems 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.
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, the Canadian Province of Quebec and the U.S. States of Alabama, California, Hawaii, Maryland, New York, Oregon (if required by local authorities), and Pennsylvania (if indicated by a sign). The UK has both advisory cycle lanes (use not required) and compulsory cycle lanes (use required).
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. John Forester’s critique
• 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.
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 http://john-s-allen.com/galleries/pdwnorth/slides/nbeaconbr.html and the following two pages in my photo album.
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.