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About bike lanes

Alan Wachtel

Here's a summary of what I see as the advantages and disadvantages of bike lanes.

On the positive side, bike lanes can add space to the roadway that, as a matter of practical politics, sometimes can't be obtained without them--for instance, by persuading a city to restripe lanes or remove parking on an existing road. This space usually makes both cyclists and motorists feel more comfortable, and, by allowing motorists to pass with less delay at a greater distance, may reduce bad feelings on both sides. (Note that this isn't the same as making the road safer.) In principle, a bike lane stripe serves the same engineering purpose as any other lane stripe, and should be employed under similar circumstances--to delineate travel paths that could otherwise be ambiguous, providing for more predictable movement. Many cyclists, for instance, might find it intimidating to share an undivided 16-foot lane with 60-mi/hr traffic.

Often a wide curb lane or a striped but undesignated shoulder would do the job just as well as, or better than, a bike lane. John Allen has observed that widening a road, painting a stripe, and signing a bike lane should be independent decisions. But the engineering standards for wide curb lanes and for shoulders are vaguer than for bike lanes; bike lanes can be readily implemented just by following AASHTO standards or the equivalent.

Just as bike lanes may be politically easier to attain than wide curb lanes or shoulders, they may also provide better protection against hijacking roadway space by restriping it for additional traffic lanes. And many people believe that bike lanes remind motorists that bicycles belong on the road, and to expect them there.

But bike lanes also have significant drawbacks. Even with the recommended dashed striping pattern, they can create conflicts at intersections. The AASHTO Guide for the Development of Bicycle Facilities (1999) states (pp. 25-27)

"Bike lanes sometimes complicate bicycle and motor vehicle turning movements at intersections. Because they encourage bicyclists to keep to the right and motorists to keep to the left, both operators are somewhat discouraged from merging in advance of turns. Thus, some bicyclists may begin left turns from the right-side bike lane and some motorists may begin right turns from the left of the bike lane. Both maneuvers are contrary to established rules of the road and may result in conflicts. . . "

I found the following startling claim in the Pedestrian and Bicycle Information Center's Bike Lane Design Guide (p. 4)

"When bike lanes are considered for streets with channelized intersections the curb lane is designated with markings and signs indicating 'Right Turn Only Except for Bikes'. This improves safety for cyclists by preventing through motorists from passing on the right while still allowing through cyclists to use the lane. . . .When the width allows, the bike lane is dotted to encourage right-turning vehicles to merge right. The bike lane then continues for a minimum of 30 feet until the stop bar."

Such deliberate channelization of right-turning vehicles to the left of through bikes is a recipe for collisions. The AASHTO Guide has it right (p. 27)

"At intersections, bicyclists proceeding straight through and motorists turning right must cross paths. Striping and signing configurations which encourage crossings in advance of the intersection, in a merging fashion, are preferable to those that force the crossing in the immediate vicinity of the intersection."

The bike lane stripe may keep bicyclists too far right in other situations, too, like avoiding car doors or traffic pulling out of side streets, and even when beginning a left turn. Again from the Bike Lane Design Guide (p. 45)

" . . . Bike lanes help to calm and organize the traffic. That means fewer accidents. That's because bike lanes help create a buffer zone at the edge of the traffic lane. This buffer improves safety for people entering or exiting their parked cars . . ."

Space between moving and parked cars is desirable, but it is not where cyclists should be riding.

Moreover, the flip side of bike lanes teaching motorists that bicyclists belong on the road is teaching them that bicyclists belong only on roads with bike lanes, and in the bike lane--leading to motorist and police harassment of bicyclists who are anywhere else, especially in states with a mandatory-use law. These beliefs often persist even in the absence of such a law; but, to be fair, they can also occur to some extent with shoulder stripes as well as designated bike lane stripes.

Because they exclude most vehicular traffic, bike lanes also tend to be magnets for debris, and are easily overlooked in road maintenance and repair.

But are bike lanes at least beneficial for inexperienced cyclists? Design standards like the AASHTO Guide and the Bike Lane Design Guide generally avoid statements about the expected skill of bicycle operators, though the AASHTO Guide does include a sketchy couple of pages on education programs (pp. 13-14; hand signals seem to be awfully important). The guideline that notoriously does talk about cyclist skill is the 1994 FHWA Selecting Roadway Design Treatments to Accommodate Bicycles, with its classification of "design bicyclists" as Group A (advanced), Group B (basic), and Group C (children). Group B and C cyclists (or their parents) are said to prefer, and to be best served by, bike lanes, shoulders, and bike paths, and a set of six tables--made up, as far as I can tell, out of whole cloth--specifies which facility to use for which bicyclists for given traffic speed, volume, and mix and sight distance.

This document says (p. 22)

"Except on residential or low-volume streets, wide outside lanes are not generally sufficient to provide the degree of comfort and safety required by less skilled bicyclists or children and will do little to encourage them to ride."

The implication seems to be that bike lanes, which are recommended for these cyclists on urban streets at all but the lowest traffic speed and volume, do provide that degree of comfort and safety. (Group A cyclists get a wide curb lane or shoulder. By the way, no facilities are deemed good enough to recommend in urban sections with parking where the operating speed is greater than 50 mi/h, even for Group A cyclists, though many of us get along fine in such conditions.)

But it's pedantic of me to cite technical standards to prove that inexperienced or casual cyclists prefer bike lanes, even though their safety benefits are questionable. Look at the activities of the majority of local and state advocacy groups, or national groups like the Thunderhead Alliance, National Center for Bicycling and Walking, or America Bikes. Most organized cyclists prefer bike lanes, and some insist the roads are dangerous without them.

Does this imply that cyclists who refuse to ride on a certain road without bike lanes, or ride there reluctantly, will be happier once the stripe has been painted? Of course it does. Will those cyclists in fact be safer--or safe enough--on the road with the stripe? That depends on whether the roadway cross section has been modified, whether the stripe serves a valid engineering purpose (like narrowing an excessively wide lane), whether the cyclists possess the necessary skill but were merely uncomfortable before, and whether the stripe changes motorist and cyclist behavior for better or worse. Those are not easy variables to control empirically. But I contend categorically that painting the stripe does not, in general, reduce the level of cyclist skill needed to navigate the road, and that if its presence attracts cyclists who lack sufficient skill, the bike lane has degraded safety.

Bike lanes don't cause me any trouble personally, and I don't see eliminating them as practical, for the pragmatic reasons I described above; they can often be useful in creating roadway width, though many of them should be wide curb lanes or shoulders instead, and current standards for bike lanes with parked cars are too narrow. The problem is the implicit and nearly universal view that engineering, important as it is, can take the place of acquiring vehicular cycling skills.

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