The Science and Politics of Bicycle Driving

It’s been ten years since I wrote this, as a sort of manifesto for the NC Coalition for Bicycle Driving effort that we kicked off then.  Although I would word some things differently if I were to write it today, it still rings true, and so I thought I’d post it here for posterity on the new site.

-Steve

The Science and Politics of Bicycle Driving

09/26/2001

Introduction

Bicycles are human-powered vehicles capable of significant speed. Bicycle driving is the operation of a bicycle according to the laws and scientific principles that apply to the operators of all vehicles on public roads. These “Rules of the Road” represent our society’s best understanding of how to minimize collisions while maximizing mobility and access for all citizens. Bicyclists have the legal rights and duties of drivers of vehicles when operating on public roadways according to traffic laws in every US state. Bicycle drivers who operate according to traffic rules for vehicles enjoy travel that is much faster and much safer than those bicyclists who do not.

Despite the history, laws, and traffic science that support vehicular-style operation of bicycles, there is a common belief that bicyclists cannot travel safely with motor vehicles. People who believe bicyclists are inferior to other road users often want to prohibit bicyclists from using roadways, and force cyclists to operate at slow speeds among pedestrians on sidewalks and trails. The motives for this prohibition are to improve convenience for motorists traveling on inadequate roads and to reduce the level of traffic competence currently expected of lawful drivers of motor vehicles. Such changes would drastically increase the dangers and reduce the convenience of travel by bicycle, as has been demonstrated everywhere it has been tried.

Many well-meaning groups, who believe they are acting on behalf of cyclists’ best interests, wish to add special markings to roads and change the Rules of the Road in order to channelize traffic by vehicle type. The motives for these changes are to increase the political visibility of bicycling and reduce the level of traffic competence currently expected of lawful bicycle drivers. But such markings and law changes have not been scientifically shown to improve conditions for cyclists, and can actually make cycling more dangerous by increasing the complexity of traffic movements and violating the scientific principles of crash prevention that led to the existing Rules of the Road. If anything is to be done to improve conditions for cyclists and the motorists who share the roads with them, such actions should be based on scientifically sound principles known to reduce collisions while preserving cyclists’ right to travel efficiently. Treating cyclists as drivers of vehicles is the most successful and feasible approach known, yet much of the treatment of bicycling and bicycle operators in the United States has been based on the assumption that cyclists are inferior users of roadways. It is long past time to debunk this myth in favor of a scientifically and constitutionally sound approach that provides for the safety and convenience of both motorists and cyclists.

Historical Background

Human beings have been constructing roadways for over six thousand years. Early roadways carried pedestrians, hoofed animals, and simple wheeled vehicles such as wagons. As traffic volumes grew, it became apparent that traffic regulations would be necessary for safety and efficiency. In ancient Rome, Julius Caesar banned wheeled traffic within the city during certain hours of the day to alleviate congestion. But because most traffic moved at the slow walking speed of humans or animals, collisions between road users could be avoided through observation and negotiation without official rules to establish right of way. In areas of high traffic, roadways would sometimes become unsuitable for pedestrians due to congestion, mud or animal waste. This led to the construction of sidewalks along the sides of urban roads to provide better conditions for walking.

The invention of the bicycle in the nineteenth century allowed sustained travel speeds much higher than was possible on foot or by horse. Bicycles were convenient and less expensive and time consuming to maintain than horses. As bicycling grew very popular, bicyclists promoted the paving of smoother roads for faster and more efficient travel. Meanwhile, pedestrians and people traveling by horse power complained about collisions and near-misses with bicyclists traveling at high speeds, and called for bicycles to be banned. Bicyclists also collided with one another, especially at intersections, because they often did not see one another in time to stop. As traffic increased in the cities, travel by any mode became quite hazardous, but it would soon become worse. Near the turn of the century, horseless carriages constructed using bicycle technology and powered by steam, electric motor, or internal combustion engine began to appear on roads. These “automobiles,” traveling even faster than bicycles, created much more severe injuries for those involved in a collision. In the early decades of the twentieth century, fatalities from automobile crashes in the cities reached epidemic proportions. Cities began to create traffic rules to reduce crashes, and traffic signals and police officers were used to direct right of way at major urban intersections.

One of the problems with the first traffic rules was that the rules were different from one city to another, or even from one street to the next. Sometimes road users would forget which rules applied in which city or on which street. Traffic signals meant different things in different places, but vehicle users would often travel between places with different rules. The resulting confusion would often create much worse crashes because each participant on a collision course would believe they had the right of way, and not slow down until it was too late. Some traffic rules were different from one type of vehicle to the next, but drivers would sometimes change between vehicles, and other drivers would often not know how to predict the actions of the driver of an unusual vehicle.

It quickly became apparent that uniform traffic laws would be needed across the country (and in fact across most of the world) so drivers could travel from place to place without needing to learn new rules. The rules would have to be simple enough for ordinary human beings to follow reliably, and would be designed to prevent, or at least minimize, crashes given the operational constraints of wheeled vehicles. All vehicle drivers would have to follow the same rules, regardless of vehicle type or maximum speed, in order for the system to work. The rules would also provide for efficient travel by making optimum use of the available roadway capacity. All drivers would need and want to cooperate by following these rules in order to travel safely and efficiently. Drivers who failed to cooperate could be punished by law.

A great deal of trial and error in those early years determined which rules worked, and which did not. Eventually the discipline of traffic science evolved to explain the abilities and limitations of human cognition and vehicle operation in traffic. It was determined that in order for vehicle drivers to avoid crashes, they needed to be able to see and predict those road users to whom they would be required to yield right of way. This information would need to come early enough for the driver to react appropriately. Because human drivers can see very well within a narrow field of view in front of them, but not well to the sides or behind, drivers of vehicles would have to yield to traffic already on the roadway ahead of them. Explicit right of way rules for junctions and lateral movements would be closely matched to the abilities of human drivers of wheeled vehicles, and head-turns would only be required in specific situations where drivers would know to expect traffic conflicts at either side. Over time, these rules were slowly and carefully updated using scientific analysis of crashes in order to minimize collisions between vehicles by addressing every potential conflict that anyone could think of.

The Rules of the Road

The Rules of the Road that all drivers follow to prevent collisions are very simple. They are based on tested theories of human perception, human cognition, and wheeled vehicle maneuverability. These principles are the same everywhere in the world, so as a result, the basic rules are similar wherever they are based on science. (In some countries the rules are mirrored because the decision of which side to drive is arbitrary.) The written laws and traffic signs may vary slightly from place to place (although in the United States they are somewhat unified by the Uniform Vehicle Code and the Manual of Uniform Traffic Control Devices) but these specifics are mostly enhancements upon the basic principles.

The basic principles that all drivers of vehicles follow (as adapted from [1]) in order to prevent collisions are listed below:

  1. First come, first served. Each driver on the road is entitled to a “safety zone”, i.e. the space their vehicle occupies, plus reasonable clearance behind and to each side, and reasonable stopping distance in front of them. Other drivers who want to use this space must first yield to the driver already entitled to it. This principle applies both between intersections and at intersections. Yielding to traffic already on the road ahead requires driving slow enough to stop if traffic just beyond view is slow or stopped, and not following too closely in case traffic ahead stops suddenly.
  2. Drive on the right-hand side of the roadway.
  3. Yielding to crossing traffic. Drivers on less important roads, and that includes driveways and alleys, yield to traffic on more important roads. Yielding means looking and waiting until the movement can be made without violating the right of way of other highway users. Drivers turning left must also yield to thru traffic traveling in the opposite direction on the road. Traffic signals or signs often indicate which road has priority.
  4. Yielding when moving laterally. Drivers who want to move laterally on the roadway must yield to traffic in their new line of travel. Yielding means looking behind, to the side, and in front and waiting until the movement can be made without violating the right of way of other highway users.
  5. Destination positioning at intersections. Drivers must approach intersections (including driveways) in the proper position based on their destination. Right-turning drivers make their turns from the right side of the roadway, left-turning drivers do so from near the center line, and straight traffic goes between these positions.
  6. Speed positioning between intersections. Drivers park on the rightmost edge of the highway. Drivers travel in a portion of right side of the road that is wide enough for them to maneuver safely and is available for thru-traffic. Where safe and practical, slower drivers operate far enough to the right to allow faster drivers to see past them and perhaps pass when it is safe to do so. Drivers should overtake slower traffic on the left, not on the right. (There are exceptions when vehicles are turning left, on multi-lane roads, and on one-way roads).

Following these six rules can prevent virtually all collisions on ordinary roads. The remaining special cases, mostly involving convenience enhancements, special facility designs, and resolution of ambiguities that arise when all parties have already stopped, are included in the traffic laws and taught as part of driver education. The Rules of the Road are simple to follow and limit the viewing area that a driver is required to watch except during special maneuvers that the driver expects. The Rules of the Road work for drivers of every vehicle type and make those drivers predictable to others.

Pedestrian Rules

Pedestrians follow somewhat different rules from drivers because pedestrians have much better maneuverability. Pedestrians can stop and change direction almost instantaneously, but drivers of wheeled vehicles cannot. Pedestrians also travel at speeds an order of magnitude slower than typical vehicle speeds, which means that merging pedestrian and vehicle traffic into the same travel lanes would severely reduce the convenience of vehicle travel. For these reasons pedestrian travel is segregated onto sidewalks on the side of those roads where vehicle speed is important. On roadways where there are no sidewalks and vehicle operators wish to pass, pedestrians are usually required to yield sufficient passing space on the roadway surface by stepping sideways. This is most important in darkness, where motorists may have difficulty seeing pedestrians who are not ordinarily equipped with lights or reflectors. Pedestrians walking on narrow roads without sidewalks must walk facing vehicular traffic in order to know when it is necessary to yield, especially at night. Note that the slow travel speed of pedestrians walking toward traffic does not significantly reduce the available reaction time for motorists or pedestrians.

Rather than expecting pedestrians to utilize destination positioning at intersections, which would require pedestrians to merge with vehicle traffic, traffic law requires pedestrians to turn at right angles and cross streets by yielding to thru-traffic, by waiting for priority from a traffic signal, or by using crosswalks (marked or unmarked). But without the benefits of destination positioning, many conflicts are created between the paths of drivers and the paths of pedestrians. Drivers turning to or from cross streets and driveways often interrupt the paths of pedestrians walking straight on the sidewalk or crosswalk. Drivers or pedestrians must often stop suddenly when a conflict appears and someone must yield. This can be frustrating to both drivers and pedestrians, and can also be very dangerous. The danger is mitigated somewhat because the straight-traveling pedestrian is moving slowly enough to see vehicles and be seen by drivers for what is usually an adequate period of time for either party to react in advance of a potential collision, and because pedestrians can yield quickly. Segregation of vehicular and pedestrian traffic is therefore a compromise that allows vehicle traffic to move with relative convenience, while also allowing pedestrians to utilize their maneuverability and stop at any time to interact with other people or facilities in the streetscape.

 

Figure 1: Classes of Road Vehicles Regulated by Traffic Law

Vehicles and Motor Vehicles

Motor vehicles are a special class, or subset, of vehicle, as shown in Figure 1. Motor vehicles include cars, trucks, buses, motorcycles, and motor scooters. Non-motorized vehicles include bicycles, tricycles, and horse-drawn carriages. Traffic law in every US State either explicitly defines bicycles as vehicles or defines bicycle operators as having the rights and duties of drivers of vehicles. All vehicle operators are legally required to obey the basic Rules of the Road as described above. These rules are codified in the state laws with language such as “The driver of a vehicle shall (or shall not) do X.” However, there are some special legal restrictions for drivers of motor vehicles given the potential dangers that motor vehicles can pose to other road users and the wear and tear that motor vehicles can cause to roadways. Such laws are usually worded as “The driver of a motor vehicle shall (or shall not) do Y.” The most obvious special restriction for drivers of motor vehicles is the legal requirement of an operator’s license.

Many people fail to understand the distinction between rules for all vehicles and special restrictions for motor vehicles. They may erroneously believe that if a vehicle does not have a motor, the operator is not required to obey the traffic laws for vehicles. Others erroneously believe that if the vehicle does not have a motor, the operator is not allowed to drive it on the road according to the normal Rules of the Road. Inspection of the traffic laws in every state makes it very clear that drivers of non-motorized vehicles have the rights and responsibilities of drivers of vehicles when traveling on every public road, except in the special case of controlled access freeways with minimum speed limits that cannot be sustained by non-motorized propulsion and which do not service local destinations. This preserves bicyclists’ constitutional right to access every destination served by public roads while still allowing a redundant system of expressways to be built exclusively for high-speed motor travel.

Bicycle Driving, AKA Vehicular Cycling

A bicycle driver follows the vehicular Rules of the Road in order to safely and efficiently take advantage of the convenience of facilities designed for vehicular travel. The bicycle driver knows that she is an equal user of the roadway, and acts like it, cooperating with other drivers and asserting herself where necessary. Cycling down a street with wide lanes, she uses the right side of the lane to allow overtaking vehicles to pass easily, then looks behind to merge with traffic when approaching an intersection, and smoothly moves into the middle of the left turn lane in preparation for a left turn. She patiently awaits a green light before proceeding, looking carefully for other road users whose paths may conflict with hers as she turns. The bicycle driver cycles down a side street taking care to stay four feet away from parked cars in order to avoid being doored. On a street with lanes that are too narrow to safely share side-by side with a motorist, she drives in the middle of the lane to provide herself room to maneuver and to avoid being squeezed off the road. When traveling straight through an intersection, she uses the through lane, never the right-turn lane, and does not pass on the right side of other drivers who might turn right. On narrow two-lane roads with heavy traffic in each direction, she occasionally pulls off the road to disperse traffic if and when it backs up behind her. When cycling at night, she equips her bicycle with a white headlight in front and a bright red reflector, and perhaps a red light, on the back. A bicycle driver is not afraid of traffic; a bicycle driver is traffic.

Bicycling in travel lanes as the driver of a vehicle is standard operating procedure for many experienced cyclists in the United States. It complies with traffic law and the scientific principles of collision prevention. Most bicycling education programs run by cycling organizations, such as the League of American Bicyclists, teach this type of vehicular-style bicycle operation. In Britain, the vast majority of cyclists drive bicycles this way. Yet many – if not most – American teenagers and adults operate bicycles very differently. Many ride on sidewalks, or in the gutter, and often against traffic. They make left turns from the right edge of the road. They run red lights, ride straight from right turn lanes, and ride at night without a headlight, all while the police look the other way. When Americans do drive bicycles in a lawful, vehicular manner, they are sometimes harassed by police and motorists. Why is this? The reason is because popular American notions about appropriate behavior by adult bicyclists have nothing to do with science or the best interests of people who travel by bicycle. Instead, American perceptions of bicycle operation are based on a taboo promulgated for the convenience of motorists.

America’s Taboo Against Bicycle Driving

American society circulates many negative messages about bicycling in traffic. Bicycling in traffic is considered by many to be reckless, foolhardy, and sometimes rude. The most common advice given to cyclists is to avoid busy roads that provide convenient access to important places; presumably cyclists should only go to unpopular destinations on undesirable and inconvenient roads. Another popular idea is that cyclists should stay as close to the edge of the road as possible in order to stay out of the way of cars. Getting in the way of cars is supposedly an invitation to certain death, because car drivers are often expected to run into anything that is slower or more vulnerable. The rules of the road that apply to bicyclists are considered obsolete because they involve merging with motor traffic, which is thought to be suicide. Roads are believed to be designed for cars and not for bicycles, which are tolerated at the pleasure of motorists, who really own the roads. Inferior bicyclists may have an obsolete legal right to use the road, but they had better stay out of the way of superior users or they will be “dead right.”

As a result of these “common-sense” beliefs, American bike-safety programs developed by motoring organizations and “pedestrian-style” bicyclists during the twentieth century attempted to teach cyclists to provide a clear path to motorists at all times by hugging the edge of the road, riding on sidewalks where present, and even riding facing traffic so cyclists can see when to get out of the way. Some towns and states tried to prohibit bicyclists from operating on important roads or roads without shoulders. Engineering projects designed for “bicycle safety” have usually involved construction of mandatory sidepaths to get cyclists off of roads and mandatory bike lanes to keep cyclists out of the way of motorists. The publicized benefit of these efforts is to protect cyclists from collisions from behind, which are widely believed to be the greatest danger to cyclists and caused by cyclists’ sinful failure to keep up with the desired speed of motor traffic. This is the taboo that afflicts American bicycle transportation policy: that bicyclists must be kept out of the paths of motorists or they will surely be killed.

From Webster’s Dictionary:

Taboo: -n 1. a. A prohibition excluding something from use, approach, or mention because of its sacred or inviolable nature. b. An object, word, or act protected by a taboo. 2. A ban or inhibition attached to something by social custom or emotional aversion. 3. Belief in or conformity to religious or social prohibitions. 4. A proscription devised and observed by a group for its own protection. -adj. Excluded or forbidden from use, approach, or mention.

We can see that the fear of bicycling in traffic meets all the definitions of a taboo. Like most taboos, it is not based on scientific understanding. Some taboos provide protection to those who cannot comprehend the complexities of the issues involved. Young children are often given bicycles as toys long before they develop the perception and judgement necessary to negotiate traffic. Teaching young children to fear traffic and get out of the road when they see cars is probably the safest way to address their cognitive limitations. This is acceptable because young children’s travel privileges are restricted to very short distances by their parents. But older children, teenagers, and adults can develop sufficient understanding of traffic principles to follow the rules of the road. They do exactly this when they learn to drive cars. Why then is the taboo allowed to persist among older cyclists, motorists, and transportation professionals? Because American bicycle transportation policy is not about improving the safety and efficiency of bicycle travel. Bicycle driving is taboo in American society because it involves occupying lane space on roadways. Failing to provide a clear path to faster motorists has become a social taboo in our pro-motoring society. This selfish interest is so powerful that promises of certain death were invented as punishment for its violation. Almost everything taught to cyclists by those who do not use bicycles for transportation has been based on reinforcement of this taboo to support the convenience of motorists.

Even though bicycle driving is the safest and most efficient approach for cyclists, vehicular-style cycling techniques have been shunned by the majority of the US population (including government entities in charge of transportation safety) because they might create delays for motorists. It is easy to see that the public’s concern is not really safety for cyclists. If government wanted to save cyclists’ lives, they would enforce laws such as those requiring cyclists to use a headlamp and rear light or reflector at night. Cyclists operating in the dark without proper nighttime equipment account for about half of all urban bicyclist fatalities. Most other car-bike collisions are caused by cyclists violating the basic Rules of the Road, which are almost never enforced for cyclists by police. (The main exception are discriminatory laws that prohibit bicycling on part or all of a roadway, and are designed for the convenience of motorists.) But rather than teaching cyclists how to negotiate traffic safely as drivers of vehicles, American cyclists have been taught that the only things they can do to improve their safety is to avoid motor traffic at all costs.

British cyclists are more likely than Americans to operate in a vehicular manner because they do not share the American bicycling taboo. Automobile use in Britain grew in popularity much more slowly than in the United States, mostly because the dense old British cities and narrow streets made bicycle travel convenient and motoring less so. For nearly a century, many British cyclists of all ages and socioeconomic classes shared crowded streets with motorists, and it became obvious to nearly everyone that the most reasonable way to minimize collisions was for cyclists to obey the same rules of the road as motorists. Over time, more people could afford cars and fewer traveled by bicycle, but by then the tradition of vehicular-style bicycle driving was well entrenched in British culture.

In the United States, by contrast, the automobile was quickly embraced as the future of transportation destined to replace all other modes. New American cities, suburbs, and road systems were still being constructed as motoring grew in popularity, which allowed them to be designed for convenient use by automobile, and inconvenient for anyone without a car or at least a bicycle. The automobile quickly became an important measure of socioeconomic status. Anyone who traveled significant distances without a car was obviously a lower class of citizen, and the bicycle was reduced to a mere child’s toy.

The boom of American automobile use in the mid-twentieth century was also a time of horrible bigotry and brutal treatment of minorities and non-conformists. Too often, the motor vehicle was wielded as a convenient weapon against anyone of the wrong “kind” who got in the way. No one would ever question the superior motorist’s inability to avoid the victim who “appeared out of nowhere.” It is therefore not surprising that many of those who could not afford automobiles in the mid twentieth century (especially minorities persecuted by racists) were not about to turn their backs to motorists while bicycling in travel lanes – or worse, delay a motorist. Americans who learned the taboo against cycling in front of motorists later taught it to their children, and they taught it to theirs. Furthermore, anyone who violated the taboo, and behaved in a socially unacceptable manner by operating a bicycle in travel lanes as an equal driver, became an object of harassment from bigots who believed it was their job to enforce their prejudicial view of the proper social order.

The taboo against vehicular bicycling encourages a different style of cycling by many American cyclists: the pedestrian-on-wheels approach. The taboo promotes cycling against traffic or on sidewalks and crosswalks, dodging pedestrians, dogs, fixed obstacles, curbs, debris, and broken pavement, while also dealing with the hazards of motor vehicle traffic crossing at every driveway and intersection. Pedestrians-on-wheels also operate at night without proper vehicle lights, because pedestrians rely on street lamps. But unlike pedestrians, cyclists cannot stop quickly, and their speed gives them less time to see collision hazards, while also giving motorists much less time to see and avoid them at driveways and crosswalks. Ironically, the result of the taboo against cycling as the driver of a vehicle is a much higher car-bike crash rate and much higher injury rate for cyclists who act as pedestrians-on-wheels, while at the same time reducing the convenience of bicycle travel. This accident trend has been confirmed by every study of bicyclist injuries and car-bike crashes conducted in North America.

The Evidence Against the Taboo

While most American bicycle owners operate as pedestrians-on-wheels, some cyclists (especially those who participate in cycling clubs) continue to operate on US roads as drivers of vehicles. Recreational and competitive club cyclists avoid using sidewalks and most multi-use paths because they know from experience that reasonably fast and efficient cycling is impossibly dangerous on such facilities. Many of these cyclists ride in urban areas with high volumes of motor traffic. Although these cyclists represent a minority of bicycle owners in the United States, they represent about 80% of bicycle miles actually traveled. Their use of roadways allows us to judge the relative danger of bicycle driving according to the Rules of the Road compared to the taboo-based pedestrians-on-wheels approach.

In 1996, Moritz [2] conducted a survey of avid adult cyclists to determine their riding habits and crash statistics. The survey corroborated other scientific studies that showed the dangers of pedestrian-on-wheels behavior. Although most cyclists worry a great deal about car-bike crashes, especially those from behind, the vast majority of injuries to cyclists involved falls and crashes with stationary objects. These include many serious injuries (such as broken bones) and some such accidents do cause fatalities. Only 11% of crashes involved moving motor vehicles. The survey revealed crash rates for different facility types as follows:

Table 1: Adult Bicyclists’ Crash Rates for Various Facility Types in Moritz Survey

 

Facility Type

Crashes per Million Kilometers

Major road without bike facilities

41

Minor road without bike facilities

59

Road signed as bike route only

32

Road with on-street bike lane facility

26

Multi-use trail (not alongside street)

88

Off-road/unpaved

282

Other (most often “sidewalk”)

1026

 

This data suggests that the crash rate for regular adult cyclists operating on sidewalks is twenty five times that of regular adult cyclists operating on major roads without bicycle facilities.

A study by Wachtel and Lewiston [3] analyzed locations of common car-bike crashes. Their results showed that the car-bike crash rate for sidewalk cyclists is about twice that of road cyclists, and the car-bike crash rate for wrong-way sidewalk cyclists is about four times that of road cyclists, normalized for traffic conditions. The remaining sidewalk crashes that account for the high accident rate reported by Moritz include falls due to poor surface conditions as well as collisions with other cyclists, pedestrians, dogs, and obstacles.

The common causes of car-bike crashes by teenagers and adults are listed in Table 2 below, adapted from Forester[4]:

Table 2: Most Common Causes of Car-Bike Collisions for Teen and Adult Cyclists

Teen cyclists Adult Cyclists
  1. Wrong-way cyclist hit by motorist restarting from stop sign
  2. Cyclist turning left from curb lane
  3. Cyclist exiting commercial driveway
  4. Wrong-way cyclist running stop sign
  5. Wrong-way cyclist head-on
  6. Right-of-way error at uncontrolled intersection
  7. Motorist entering commercial driveway
  8. Cyclist running red light
  9. Cyclist turning left from curb lane, hitting car coming from opposite direction
  10. Wrong-way cyclist hit by motorist turning right on red
  1. Motorist turning left
  2. Signal light change
  3. Motorist turning right
  4. Motorists restarting from stop sign
  5. Motorist exiting commercial driveway
  6. Motorist overtaking unseen cyclist (mostly in darkness)
  7. Motorist overtaking too closely
  8. Cyclist hitting slower-moving car

 

The most common causes of car-bike crashes involve failure of cyclists to obey the vehicular Rules of the Road and consequently operating in an unpredictable manner. Particularly dangerous is wrong-way cycling which causes the most common crashes as shown in Table 2. Wrong-way cyclists approach intersections where motorists are not looking for vehicles, and the combined speed of the motor vehicle and bicycle makes avoidance more difficult and crashes more traumatic. Of those crashes that do involve lawful cyclists and are caused by motorist error, most are caused by turning and crossing actions, not overtaking. Visible and predictable operation as the driver of a vehicle at intersections prevents crashes caused by cyclists and maximizes cyclists’ ability to avoid motorists’ errors, while behaving as a pedestrian-on-wheels greatly increases the likelihood of being in one of the most common crash types listed in Table 2.

Motorists-caused overtaking-type collisions amount to just 2% of all urban car-bike collisions in daylight, and about 0.3% of all accidents to urban daylight cyclists. However, overtaking-type crashes caused by motorists traveling at high speed in daylight are somewhat more likely to result in fatalities, resulting in much greater levels of public attention to a small number of crashes. Besides maximizing their visibility and riding straight, there is little that cyclists can do to reduce this low probability of crash without increasing the likelihood of the much more common types of crashes at intersections. The best way to effect reduction of the rare motorist-error overtaking-type crashes is to recognize the typical causes, which are:

  • Motorist impairment (drugs, alcohol, etc.)
  • Extreme motorist negligence
  • Reckless driving
  • Motorist unfit to drive due to vision or health issues

Motorists who claim that they may not be able to avoid running down a slow cyclist from behind quickly abandon that argument when they realize they are arguing the case for their own incompetence. Avoiding a rear-end collision with a slower vehicle traveling continuously in the same direction is the easiest traffic task required of drivers of vehicles. This action is performed repeatedly when driving in traffic with no difficulty, because the potential conflict is right where the motorist is looking and can be seen well in advance. Slow or stopped vehicles typically include drivers waiting to turn left or waiting for signals at intersections, traffic slowed due congestion, school buses, mail trucks, tractors, and garbage trucks. Slow traffic on ordinary roads is not dangerous; slow traffic is an inevitable part of the traffic mix in the real world. Failure to avoid rear-ending slower road users indicates a driver’s gross negligence, failure to drive within his sight distance, failure to maintain control of his vehicle, or lack of basic fitness as a driver. Such drivers are a threat to the safety of everyone else on the road and not just to bicyclists in particular. The severity of error involved in such collisions is sufficient for such a motorist to cross a double-yellow line or run a red light and kill another motorist. These drivers usually crash into trees, pedestrians, or other motorists before they get a chance to hit a bicyclist. The most effective way to remove such bad drivers from the roadways is through the existing mechanisms of traffic law enforcement designed to ensure safe drivers on safe roads, although these mechanisms may need to be given greater strength and attention.

 

As cyclists become more knowledgeable about cycling in traffic, they are less likely to behave as pedestrians on wheels and generally more like drivers of vehicles. This is reinforced by participation in recreational road cycling organizations. The relative accident rates (including falls) for children, adults who cycle at college campuses, and recreational club cyclists are given by Forester [4] and compared in Table 3.

 

Table 3: Accident Rates (All Types) for Different Types of Cyclists

 

Cyclist Type

Miles per accident

Children

1,500

College-associated adults

2,000

Club cyclists

10,000

 

Overall, the probability of injury per hour of cycling is lower than that for most sports, and the probability of death per hour is about the same as that of motoring. Cycling is not dangerous enough to discourage competent bicycle drivers from cycling wherever they want to go. The best approach to increase the safety and convenience (and thus volume) of bicycle transportation is to improve the traffic habits of bicycle drivers. Unfortunately, the benefits of vehicular bicycle driving technique and the relatively low likelihood of overtaking collisions have been largely ignored by the American public and by American bicycle transportation planners. Why? Because this evidence does not support the taboo-based pedestrian-on-wheels paradigm and does not keep cyclists out of the way for the convenience of motorists.

Preserving Convenience for Motorists

The effect of bicycle traffic on total traffic throughput on wide-lane roads and multi-lane roads is negligible, and may in fact be positive. However, on multi-lane roads with narrow lanes, bicyclists can cause motor traffic to slow temporarily as motorists merge laterally to pass. On two-lane roads with narrow lanes and heavy oncoming traffic, slow bicyclists can cause significant delay to a motorist waiting for an opportunity to pass. These are cases where the roadway is not adequate to handle the demand placed on it by users without a reduction in level of service. The appropriate response to reduce traffic congestion, when practical and desirable, is to widen the road. Wide outside lanes allow motorists to pass cyclists safely and easily while still treating cyclists as part of the vehicular traffic stream operating in travel lanes. Under no circumstances should bicyclists be prohibited from substandard roadways or required to squeeze over and use inadequate pavement space to allow motorists to pass at unsafe distance, because such discrimination and endangerment is unconstitutional. However, it is fair to expect cyclists and motorists to share equally in the inconvenience of inadequate road design. On narrow two-lane roads where traffic backs up behind a cyclist, a courteous cyclist should pull off the road periodically to allow waiting vehicles to get past.

Some states (not including North Carolina) have laws that dictate a maximum number of vehicles that may back up on a two-lane road before a slow vehicle is expected to pull off the road. The California Vehicle Code has such a rule:
CVC 21656. On a two-lane highway where passing is unsafe because of traffic in the opposite direction or other conditions, a slow-moving vehicle … behind which five or more vehicles are formed in line, shall turn off the roadway at the nearest place designated as a turnout by signs erected by the authority having jurisdiction over the highway, or wherever sufficient area for a safe turnout exists, in order to permit the vehicles following it to proceed. As used in this section a slow-moving vehicle is one which is proceeding at a rate of speed less than the normal flow of traffic at the particular time and place.

Such an approach is a much more appropriate way of addressing the convenience of motorists than discriminating against bicyclists as a class or requiring them to operate in a dangerous manner.

 

The Problem of Bikeways

Many Americans believe that segregated bike lanes and bike sidepaths – we’ll call these facilities bikeways – were invented to make cycling safe by reducing crashes and injuries to cyclists. This belief is incorrect. American bikeway designs are mostly inferior copies of rather dangerous bikeways in Holland, which were originally created to clear dense bicycle traffic from Dutch roadways for the convenience of motorists. Dutch cities are very compact, with flat topography, making bicycle travel very convenient. When automobiles first became popular in Europe, it was virtually impossible to drive them at speed in the Dutch cities due to the high numbers of bicyclists on the roads. To allow higher motor vehicle speeds, bicyclists were prohibited from certain roads or lanes, and bicycle-only paths and lanes were built alongside those roads to provide bicycle access to the same places. Unfortunately, this segregation caused dangerous conflicts at driveways and intersections. To mitigate the problem, special traffic signal phases were added at intersections to allow bike path traffic to proceed when motor vehicle traffic was stopped, and vice versa. These signal phases reduce traffic throughput because they reduce green time in half for every direction, and therefore reduce convenience for both motorists and cyclists. However, these tradeoffs were acceptable to the Dutch in order to allow greater motor vehicle speeds than would be possible with the prevalent speeds set by large numbers of bicyclists.

In the United States, traffic engineers first proposed the use of Dutch-style segregated bikeways in the early 1970s in response to concerns that the recent surge in the popularity of roadway bicycling might grow to cause congestion problems and inconvenience for motorists. The proposals of this era skipped the separate signal phases at intersections to save money and avoid delaying motorists, but as a result the designs were far too dangerous to pursue. The few sidewalk-style bike paths that were built parallel to streets generated much higher cyclist crash rates than use of the original streets, as one might predict given the data for sidewalk crashes given earlier in Table 1. In the decades that followed, traffic engineers worked to reduce the dangers of the segregated facilities until some designs were found to be almost as safe for pedestrian-style cyclists as normal roads. On-street bike lanes were determined to be the least dangerous, but problems still occurred at intersections because the bike lanes often placed straight-traveling cyclists to the right of right-turning motorists, and encouraged cyclists to turn left from the right side of the street. Bicycle lanes placed the cyclist in a less visible position away from the traffic stream watched by motorists, which increased the probability of oncoming drivers turning left in front of the cyclist or driving out from a side street in front of the cyclist. The bike lanes also generated build-up of debris, were not designed or maintained to the same standard as normal travel lanes, and were often blocked by parked cars or pedestrians. Some bike lanes forced cyclists to ride next to parked cars, inviting injury when doors opened. When cyclists rode outside the bike lanes for any reason, police would ticket them and motorists would harass them. The root of the problem was the way the white line indicated segregation by vehicle type, despite the safety requirements for destination positioning at intersections and speed positioning between intersections. Without such segregation, these problems do not occur and motorists can still pass reasonably well. The best approach is to simply treat cyclists as drivers who follow the normal rules of the road and merge with other traffic where conditions require. Thus wide outside lanes are the preferable facility design for important roadways shared by cyclists and motorists.

Some advocates for greater volumes of bicycle transportation advocate construction of segregated bikeways because these facilities are consistent with the pedestrian-on-wheels paradigm and conform to the public’s taboos about traffic. It is also incorrectly believed by some that segregated bikeways are what created the high volumes of bicycle transportation in Holland, when history shows otherwise. But transportation facility design should be based on science, which supports the principle that bicycles are vehicles. Off-street shortcuts and rail-trail bike paths are popular among novice and child cyclists and are pleasant slow-speed routes used by some commuting cyclists. The crash rate for such facilities is higher than roads, as shown in Table 1, but not unreasonably so. Construction of recreational and short-cut bike paths in some places is probably a good idea, but these routes must never be designed to run alongside streets and cross driveways and intersections like sidewalks do. Such configurations are much more hazardous and much less convenient for cyclists than using the roadway. Unfortunately, there are few places such paths can be built affordably outside highway rights-of-way. Furthermore, off-street bike paths do not promote (and in fact may retard development of) the bicycle driving skills required to negotiate vehicular traffic on ordinary roads. Bike paths and bike lane stripes are therefore unlikely to make significant improvements in the safety and convenience of bicycle transportation for the majority of miles of bicycle travel.

Non-Discriminatory Engineering

The design of ordinary roadways (unlike controlled access freeways) must start with the assumption that bicyclists will operate on those roads in travel lanes as drivers of vehicles, following the ordinary Rules of the Road (including use of proper lanes based on destination). Bicyclists should not be segregated into “separate but equal” paths, bike lanes, or shoulders because these facilities are never really equal. Segregation violates the safety principle of destination positioning at intersections, encourages accumulation of debris, substandard surface conditions, parked cars, pedestrians, and other obstacles in the segregated facility, and places cyclists where other road users are not ordinarily looking for vehicles. Bicycle drivers operate in travel lanes because everyone knows how traffic ought to operate in travel lanes, everyone knows to look for vehicular traffic in travel lanes, and the use of travel lanes by motorists means that their maintenance and continuity will be given reasonable attention (unlike paths, bike lanes, and shoulders.) At first, a wide paved shoulder may seem like a wonderful facility for bicycling, but the benefits of extra space are often wasted. Poor maintenance or debris can make the shoulder too hazardous for cycling, and right turn lanes or other stripes at intersections require the cyclist to merge into the through lane to avoid the turn lane and traffic exiting or entering the roadway. Cyclists should never be expected to ride straight in right turn lanes, or worse, to the right of right turn lanes. In most cases, the same width of asphalt is better used as wide outside lanes, where cyclists will position themselves based on speed or destination as necessary.

Every roadway where bicycling is permitted is, by law and in practice, a bicycle facility. Contrary to popular belief, every travel lane of every roadway provides sufficient space for bicyclists. What?!! Yes, every travel lane of every roadway that is wide enough to accommodate normal-width motor vehicles is wide enough to accommodate bicycles. What is missing from some roads is the space for motorists to overtake bicycle drivers at safe and legal distance without the overtaking motorists moving into the adjacent lane, partially or completely. Additional roadway width is not a bicycle facility; the bicycle facility is already there. Additional roadway width is a convenient passing facility. This analysis of how roads currently operate agrees with traffic law and constitutional principles that protect the travel rights of bicycle drivers, unlike the discriminatory, taboo-based bikeway system.

Additional road width probably provides subtle improvements in safety to cyclists, as suggested by data in Table 1. This has not been proven conclusively by any study at the time of this writing, because the overtaking crash rates are so low that they are hard to measure accurately for different road types, and because nobody promoting segregated bikeways ever cared enough to study the actual effects of road width on cyclists’ crash rates. But under no conditions should the lack of a clear path for motorists to pass cyclists without delay be construed as an unreasonably unsafe facility for cyclists. Overtaking drivers are obligated by the rules of the road to drive within their sight distance and respect the right of way of those users already on the road ahead of them. Enforcing this principle for the benefit of cyclists also benefits every other user of roadways. Obedience of this principle occurs because those motorists who ignore it inevitably crash into slow or stopped motor vehicles. In any event, overtaking-type collisions represent a tiny fraction of injuries to urban daylight cyclists. Bicycle drivers will inevitably use every roadway regardless of its design. The decision of road width should be based on the relative importance of reducing friction between bicyclists and motorists, the desired operating speed of the roadway, and the costs of the facility.

Bicycle drivers should be expected to obey all traffic signals. In return, all traffic signals that require sensing of the vehicle in order to operate properly should also sense bicycles. Otherwise, bicyclists are encouraged to ignore red lights that will never turn for them, which perpetuates the myth that cyclists do not or need not obey the traffic laws. Bicycle drivers should not be expected to proceed against a red light or wait for an automobile to arrive. Nor should bicycle drivers be expected to dismount and operate pedestrian signals, because this encourages unsafe and inefficient pedestrian-on-wheels behavior. Traffic signals that detect bicyclists operating in travel lanes as drivers of vehicles protect the safety and convenience of bicycle travel.

Empowerment through Education

Empirical evidence and analysis of the most likely causes of crashes show that bicyclists who operate as drivers of vehicles according to the Rules of the Road enjoy travel that is much safer and much more convenient than those who do not. Unfortunately, the taboo against vehicular-style cycling discourages many novice cyclists from discovering or practicing proper vehicular technique. Recreational and sports-oriented cycling clubs are one avenue through which cyclists are indoctrinated into the practice of vehicular cycling. Club cyclists are taught by other cyclists and realize through their own experience how they can optimize their safety and speed when cycling on roadways, and are thus able to unlearn the taboo. Cyclists who do not belong to such clubs are rarely taught how to drive a bicycle effectively on roads and are unlikely to discover the merits of vehicular cycling on their own. They may never develop a sense of entitlement to use roads, or to operate safely and efficiently. The social taboo is often too strong for these cyclists to give up their behavior as pedestrians-on-wheels.

It does not have to be this way. Basic instruction in bicycle driving can effectively teach older children, teens, and adults to avoid the most common causes of crashes and injuries to novice cyclists, and minimize the risk of the less common crashes, while operating with much greater efficiency. Formalized instruction that includes on-bike practice in traffic under the supervision of a competent instructor provides a rate of skill improvement faster than participation in club activities and much faster than trial and error. (It is often not enough to merely read about or see vehicular cycling; cyclists learn best by doing, and repeating the practice until they get it right.) Graduates of such programs eventually develop the confidence to travel by bicycle virtually anywhere as they extrapolate from the basic vehicular principles and improve their performance. They also go on to become better motor vehicle drivers, since their traffic skills are already developed while driving bicycles and all they need to learn are the particulars of motor vehicle operation.

We know that on-street bicycle driving education works to greatly reduce the crash rate per mile of bicycle travel, and promotes bicycle travel in general. Why then, with the millions of dollars government spends on bike paths, bike lanes, and enforcement or promotion of helmet use, do we not see government pursuing effective vehicular cycling education programs? Why does the government spend millions of dollars to heavily subsidize public bus systems that provide the carless slow service to a few destinations, but not help people learn to travel quickly, independently and inexpensively on bicycles anywhere they want to go? In fact, some in government do try to promote vehicular cycling education, but those who control the money still view bicycles as toys, and view bicyclists as hopelessly incompetent children who will never posess the skill to operate in traffic. (In fact, they do not believe safe bicycle operation in traffic is humanly possible.) Those government decision makers with any real power do not value the ability to travel by bicycle safely and efficiently; they are more interested in improving convenience for motorists by keeping bicyclists out of the way, and providing park facilities for their children to play on toys without worrying about traffic. Their idea of crash prevention is traffic avoidance, and any safety issue that cannot be solved by relocating cyclists they attempt to address with helmets. The idea of actually teaching cyclists to ride in traffic is politically unpalatable because it violates a popular taboo, and many people don’t believe that cyclists need or deserve to travel on important roads, because important roads are believed to be intended for exclusive use by motorists.

Transportational bicyclists are a minority, and politicians are unlikely to choose unpopular scientific conclusions over a popular taboo. Meanwhile, school systems are far too conservative to give up teaching dodge-ball and football in favor of teaching something as controversial and supposedly dangerous as vehicular bicycling. It therefore falls to avid bicycle drivers to educate the rest of society. Cycling organizations can organize vehicular cycling classes, and individual cyclists can invite beginning cyclists out to ride and teach them the basics. All cyclists must do their best to obey the rules of the road and provide a good example to those who are watching. This includes cooperating with motorists and helping them to overtake when it is clearly safe to do so and does not create unfair delay to the cyclist. Whenever a politician or other public figure spreads misinformation about cycling or perpetuates a taboo, cyclists must respond to refute this with good information and logic.

Enforcement

People whose perception of bicycling is shaped by taboo do not believe that the Rules of the Road are useful for improving the safety of bicycle travel. Rather, they believe that the Rules of the Road cannot be followed by bicyclists because the rules require cyclists to merge with motorists, and this will result in certain death. Most police share this belief and focus their enforcement efforts on those behaviors that affect the safety of others, with the exception of bicycling prohibitions and mandatory helmet laws promoted by politicians. There is little public enthusiasm for enforcing ordinary traffic laws for cyclists. The result is that many bicyclists operate in a lawless manner, running red lights, riding against traffic, operating at night without proper lights, and so forth, often with tragic consequences. This creates a negative impression of cyclists and marginalizes those cyclists who obey the law. Lawful bicycle drivers suffer backlash from citizens who blame them for the actions of others of their kind, even though individual cyclists have much less power to influence the actions of other cyclists than does law enforcement by police. By not enforcing the most basic Rules of the Road for cyclists, society perpetuates high bicycling accident rates, promotes prejudice against cyclists, and undermines the legitimacy of bicycle transportation. This must change to improve conditions for cyclists. Law enforcement must also publicly support cyclists’ right to operate on roadways in travel lanes and punish those who harass or endanger road cyclists. One way to accomplish this is for police to drive bicycles on roadways according to the Rules of the Road that apply to drivers of vehicles. This will reveal any conflicts that need to be remedied, be they inconsiderate motorists or inadequate roadways, and will educate the public about cyclists’ rights and responsibilities. Enforcement, education, and engineering must be organized to work in concert according to the same scientific and legal principles in order to improve conditions for safe and efficient bicycle transportation.

Conclusions

All drivers of vehicles must cooperate – not compete – in order to share our public highways safely and efficiently. The most effective basis known for cooperating is to follow the Rules of the Road. The Rules do not discriminate by the size, power, or weight of vehicles, and are based on simple, uniform concepts adapted to the capabilities of human drivers. Empirical evidence and scientific analysis shows that bicycles have the operational characteristics of vehicles, and that their operators fare best when they follow the Rules of the Road and are respected by other users and roadway engineers as drivers of vehicles. This is the status quo in the traffic laws of every state. Bicycle driving works because it avoids the multitude of right-angle collision hazards experienced by pedestrians-on-wheels in favor of the superior visibility and predictability afforded by traveling with the flow of vehicles.

Segregation by vehicle type violates the fundamental principles of crash prevention and unfairly discriminates against bicyclists. Bicyclists have a legal – in fact constitutional – right to travel public roads and access every destination they service. Segregation should not be permitted except where there is scientifically valid evidence that the operational advantages significantly outweigh the disadvantages, and alternative access facilities are available. On most roads, speed positioning and/or courteous behavior by cyclists is sufficient to provide adequate convenience to faster vehicle operators. Bicycle drivers have a responsibility to operate in a visible and predictable manner in order to facilitate safe sharing of roads. However, cyclists are not obligated to provide a clear path for motorists to overtake immediately. The presence of a path for overtaking is a convenience for motorists, and may be provided with the assistance of courteous cyclists under the right conditions, but must never be considered a prerequisite for crash prevention. All drivers of vehicles are required to drive no faster than their sight distance allows for them to slow or stop to respect the right of way of other users on the roadway ahead. In places where ease of overtaking slow traffic is important to motorists, the roadway should be designed with appropriate width.

Cyclists are not at the complete mercy of other users and roadway engineers for their own safety. By acting predictably, following the rules of the road, staying alert to the actions of other drivers, being assertive, and being prepared to take evasive actions in those rare occasions where they are necessary, bicycle drivers find their travel to be reasonably safe and efficient on virtually every road. Doing this requires the rejection of the taboo that casts cyclists as inferior users of roadways, and development of a sense of entitlement to travel wherever one wants to go. Understanding the scientific principles of bicycle operation and accident avoidance, followed with the successful experience of using it in practice, is the best way to build this confidence. The empowerment of bicycle driving makes travel by bicycle more enjoyable and more convenient than any other known technique.

[1] Student Notebook, Effective Cycling Road IFirst Edition, League of American Bicyclists, Washington, DC, 1996

[2] Moritz, W. Adult Bicyclists in the United States: Characteristics and Riding Experience in 1996. Transportation Research Record 1636: pp. 1-7, 1998.

[3] Wachtel, A. and Lewiston, D. Risk Factors for Bicycle-Motor Vehicle Collisions at Intersections; ITE Journal, September, 1994

[4] Forester, J, Effective Cycling, MIT Press, 1996.

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