Implications of Universal Access Principles for Bicycle-Specific Roadway Markings
The universal access paradigm promotes preservation of legal, safe, and efficient bicycle transportation to all destinations served by the public road system. The fundamental principles that define the performance goals of universal access as related to bicycling are as follows:
1. Universal Access to Destinations
All destinations served by the public road system shall be accessible to cyclists.
2. Equal Rights of Use
People's right to use that portion of a street designed for travel is not diminished by less weight, less size, or less average speed associated with their travel mode.
3. Integration of Modes
Travel by different modes shall not be segregated by law or facility design unless there is compelling, objective, scientifically valid evidence of operational advantages of segregation that outweigh the disadvantages.
4. Uniformity and Simplicity
Use of a transportation facility must be simple and intuitive based on uniformity with other facilities.
5. Accessible Surfaces
Roadway surfaces should be as clear as possible of hazards for narrow tires such as bicycle wheels.
6. Crossable Roadways
Crossing distances at non-signalized access locations must not exceed the distance that can be covered at slow cycling or walking speed before traffic can arrive from beyond sight distance. Traffic signal timing should provide adequate clearance intervals for safe crossing by pedestrians and slow vehicles.
7. Appropriate Space for Use
Adequate space for maneuvering and recovery should be incorporated for all vehicle operators; Overtaking activities should take place at distances appropriate for the difference in speed, maneuverability of modes, and vulnerability of users.
Discussions of roadway design related to bicycle transportation frequently turn to the controversial subject of bicycle-specific lane markings. Although many people automatically believe that such markings are helpful to bicyclists in some way, there is widespread dissent from this belief among experienced cyclists who point out a multitude of operational disadvantages caused by adding such markings and segregation rules to roadways. Such disadvantages include debris accumulation, inadequate width, improper positioning, and confusion of the public about the ordinary rules of the road. Although research studies have attempted to show a net safety benefit from the addition of bike lane markings to a given width of pavement, none has succeeded to date, and the few that purport to do so use faulty data gathering or analysis [Pein 2003]. This is because the only type of collision a bike lane stripe could prevent - improper motorist overtaking of cyclists - is so rare that the effects of the markings on collisions have been impossible to measure. In one study [Harkey and Stewart (1997)], motorists were observed to overtake cyclists in marked bike lanes at closer distances than on unmarked roads, suggesting that the striping may generate a false sense of security among motorists. More investigation is needed to determine if there are any conditions under which bike lane striping does reduce crashes. Without the support of direct safety evidence, proponents of bike lane stripes use a number of other arguments to support bike lane striping. These include the following:
Unfortunately, the validity of each of these arguments is difficult to test, and as yet they are unproven. Given the emphasis on social merit and cultural influence associated with the promotion of bike lane striping, it is useful to compare the compatibility of bicycle-specific roadway striping with the social, legal, and operational principles of universal access. Six of the enumerated principles are relevant to bicycle-specific lane markings.
Appropriate Space for Use (Principle 7)
One of the arguments made in support of bike lane striping is that it supposedly creates roadway space for cyclists. Striping opponents point out that it is the pavement width that provides space for cycling, not the bike lane markings. Bicycles are narrower than many other vehicles on the road and so they require less space for travel - somewhere between four and eight feet of pavement width for balance and recovery depending on bicycle speed. When traveling at slow speeds uphill, a cyclist needs less space than when descending at high speeds, where adequate shy distance from the pavement edge and improved sight lines are necessary for safety. All roadways designed to accommodate wheeled vehicles provide adequate space for cycling (a road designed to accommodate 8ft wide 20 ton vehicles clearly accommodates a 2ft wide 25lb bicycle.) What is typically an issue of concern is the availability of remaining roadway space for same-direction overtaking by other vehicle operators.
If a marked travel lane is too narrow for the driver of an automobile or similar wide vehicle to overtake a cyclist at safe and legal distance completely within that lane, then overtaking drivers must move into adjacent lane space to pass. The convenience and safety of changing lanes in order to pass cyclists depends on the volume of traffic in the adjacent lane, the direction of that traffic, the available sight distance, and the travel speeds involved. In many cases, such as slow residential access streets and congested downtown streets, passing is not necessary or can be postponed without significant inconvenience. On roadways that carry more traffic at higher speed, adequate width for same-lane passing of bicycles by wider vehicles may be warranted. This requires about 14' of pavement width for automobiles passing cyclists, or about 16' if shy distance to curbs or opposite direction traffic is included. On very high-speed roads or where truck traffic is heavy, even more space may be preferable.
Drivers of all types of vehicles - wide or narrow, fast or slow - determine appropriate lateral positioning not by vehicle type, but by context. A competent bicycle driver positions their vehicle within the traveled way according to the situation. When preparing to turn left, the cyclist will approach the center of the traveled way. When preparing to turn right or when facilitating same-lane passing by other through traffic, the cyclist will travel near the right side of the traveled way. Cyclists not traveling in a group will facilitate same-lane passing when conditions are favorable, including sufficient usable lane width. Otherwise the cyclist will travel near the center of the lane.
A diversity of low-speed vehicles of varied widths and power sources are legally operated on public roadways. Marking of narrow bicycle-specific lanes on roadways complicates the issue of providing appropriate space for use of a variety of vehicles driven to a variety of destinations.
Universal Access to Destinations and Equal Rights of Use (Principles 1 and 2)
Access to every destination requires travel access on every street that serves local destinations. The public must understand that cyclists have the right to travel on every street in order for society to respect and protect their safe passage to these destinations. Bicyclists currently have the right to operate on ordinary roadways and are assigned the legal rights of drivers of vehicles in all 50 states. Proponents of bike lane markings contend that bike lane markings tell motor vehicle drivers that cyclists belong on the road. Bike lane skeptics counter that that such markings convey only that bicyclists belong in bike lanes. If bike lane markings are required to symbolize the legitimacy and normalcy of roadway use by cyclists, they argue, then cycling anywhere outside of bike lanes becomes viewed as less legitimate in the minds of the public. Many or most roads cannot be easily reconfigured to accommodate even substandard bike lane markings (nor should they be); such roads must not be cast as inappropriate or unexpected places for cycling just because they are ordinary.
Integration of Modes (Principle 3)
All users deserve to have access to the best existing public facilities available for their travel mode. If a particular user group is prohibited or discouraged by government from using some part of a facility in favor of another, this raises concern over the suitability of the segregated facility for their travel. Oftentimes separate is not equal, especially if the segregated group is a minority population with limited political power. It is therefore important that users not be segregated unless there is compelling, scientifically valid evidence of operational advantages of segregation that objectively outweigh the disadvantages.
There is significant evidence that segregation of pedestrian traffic from vehicle traffic, including bicycle traffic, improves safety and comfort for all parties if reasonable walkway facilities are provided, because pedestrians and vehicle operators have fundamentally different maneuverability and pedestrians are much less visible at night than are vehicles. Segregation between different types of vehicles, however, almost always has more disadvantages than advantages because such segregation conflicts with the normal rules of the road, in particular destination positioning at intersections. As a result this makes travel less safe and/or less convenient unless extraordinary engineering measures are taken to remove the conflicts.
Bicycle-specific lane markings imply that cyclists should stay in the bike lane and other users should stay out. But safe, competent road users including motorists and cyclists must often violate this type-specific segregation in the course of their safe travel, and as a result they endure social stigmatization. The cyclist who uses a left-turn lane when making a proper left turn will inevitably face harassment from a motorist who believes that this action is not allowed. The motorist who merges into the bike lane area in preparation for a safe right turn will inevitably face harassment from a cyclist who believes that this action is not allowed.
Many skeptics of bike lane striping point out that bike lanes are often vastly inferior in design and maintenance, and thus performance for cyclists, compared to ordinary travel lanes. Poorly engineered bicycle lanes are often:
Outrageously narrow marked and signed "bike lane" beside a ditch in Carrboro, NC (Wayne Pein Photo)
Bicyclist fatality involving the opening of a car door into a marked bike lane in Cambridge, MA (Robert Winters photo)
Storm debris and sand fill this bike lane in Cary, NC, after the ordinary travel lane is swept clean (Steven Goodridge photo)
In these cases most competent cyclists will prefer to operate outside of the marked bike lane, but face potential harassment from motorists and possible ticketing by police. Some states (such as New York) and cities have laws requiring that cyclists use the marked bike lane if one is present. One must wonder why such laws were necessary to compel usage if striped bike lanes were truly superior facilities for cycling. Unfortunately, bicycle-specific lane markings can too easily result in government-sanctioned persecution of cyclists using any other part of the roadway, and as a minority the cycling population lacks the political clout to ensure that bike lanes are of equal quality to ordinary lanes.
Uniformity and Simplicity (Principle 4)
Vehicle traffic is carefully choreographed according to the Rules of the Road in order to minimize collisions. These rules are based on the maneuverability constraints of vehicles and the limited perceptual abilities of human beings. Uniformity of the Rules from one facility to another and from one vehicle to another enables more rapid and reliable user behavior.
Two of the most fundamental rules of the road are as follows:
(1) Destination positioning at junctions. Drivers of vehicles must approach junctions with roads and driveways in the proper position according to their destination. Right turning-drivers make their turns from next to the curb, left turning drivers do so from near the center line, straight traffic goes between these positions.
(2) Travel positioning between intersections. Except where destination positioning requires otherwise, drivers travel near the right side of the traveled way, except when passing. Note that when lane lines are present, drivers (including cyclists) are not required to move near the right side of the marked lane that they are traveling in.
The appropriate positioning of bicycles and other vehicles on a roadway depends entirely on context. The various scenarios include
The striping of a bicycle-specific travel lane implies accommodation of just one traffic scenario: A motor vehicle driver passing to the left of a bicyclist. All of the other scenarios require operators to ignore the indications of the bicycle-specific roadway markings and position themselves appropriately. If they don't, they face greater risk of crashes. The majority of real-world car-bike crashes do not involve overtaking by motorists; they involve intersection and driveway conflicts that are exacerbated if cyclists employ improper destination positioning, attempt to pass on the right, or operate too far right for their speed. Bike lanes' segregation of traffic by vehicle type conflicts with the basic Rules of the Road because the lane designer cannot know the destinations of the users, the relative speeds of the users, or the potential danger posed by hazards at the roadway edge at a specific time and place. Bike lane stripes make traffic negotiation more confusing because of the contradictions they create, and as a result detract from the uniformity and simplicity of road facilities. Such confusion is especially harmful to novice cyclists, who if they are encouraged by the bike lane stripe to cycle may not know when it is more appropriate to ignore the bike lane stripe. A better road design would provide the same pavement space without the bike-specific markings, so that the diversity of vehicle operators can position themselves as the traffic context requires.
Accessible Surfaces (Principle 5)
Surface conditions often deteriorate at the edge of roadways due to weaknesses of the pavement near its edge and the accumulation of debris swept away from the heavily trafficked portions of the roadway by the movement of motor vehicles. Cyclists must often operate well to the left of these surface hazards to avoid potential tire and wheel damage or loss of control.
When bike lane striping is added to a roadway, bicyclists are instructed by the markings to operate close to the edge of the road, where debris naturally accumulates. Meanwhile, drivers of motor vehicles are told to operate farther from the edge of the road, regardless of the presence of cyclists. Since the movement of motor vehicles no longer sweeps the rightmost portion of the roadway, more debris often accumulates with the addition of the bike lane stripe than without. This creates a dilemma for cyclists: they can ride through the debris in the bike lane, or they can operate outside the marked bike lane and deal with increased harassment from motorists who wish to put cyclists "in their place" or face the risk of ticketing by police for not using the rightmost lane available. Although some municipalities employ maintenance crews to try to keep bike lanes swept, such maintenance is often inadequate, and is usually an early victim of budget cuts when money is tight.
Efforts to add bicycle-specific markings to roadways conflict with the principles of universal access by segregating cyclists from ordinary road users as a special interest group and creating operational problems that likely outweigh any potential operational advantages in most cases. Bike-specific markings treat cyclists as unusual road users who should operate on unusual roads, rather than as ordinary road users who are legitimate travelers on all ordinary roads. More rigorous scientific study is needed to determine what if any potential operational benefits bike-specific markings may provide compared to simply increasing the amount of pavement space available for road sharing via wider outside through lanes. In the meantime, the social and operational disadvantages of such markings should not be ignored. Communities would be wise to take pause and avoid striping bike lanes just for the sake of bike lanes, especially if the long-term goal is to provide universal access for cyclists and to mainstream bicycling into the local culture as an ordinary use of ordinary roads. Caution should always be taken in the design and employment of traffic control devices in order to avoid doing unintended harm to vulnerable members of the public.
Pein, Wayne: Critique of A Comparative Analysis of Bicycle Lanes Versus Wide Curb Lanes: Final Report (FHWA-RD-99-034), and Bicycle Lanes vs Wide Curb Lanes: Operational & Safety Findings and Countermeasure Recommendations (FHWA-RD-99-035), 2003, http://www.humantransport.org/bicycledriving/library/critique_blvswcl.pdf .
Harkey and Stewart.Evaluation of Shared-Use Facilities for Bicycles and Motor Vehicles, Transportation Research Record 1578, 1997, pp. 111-118.