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This report presents a comprehensive picture of the type and frequency of bicycling accidents common to adult bicyclists using America's streets and highways. The estimated 500,000 to 1,000,000 bicycle accidents that occur on our roadways each year have never been fully understood. Much of the data is elusive. This report attempts to "crack" at least a part of that wall, developing accident frequencies by type, offering profiles of accident versus non-accident riders, listing primary and secondary accident causes, and showing the interrelationship between cyclist behavior, motorist influence, roadway conditions, and bicycling accidents.

This detection is made possible as a result of the operation of the Bikecentennial event, a well-documented, summer-long inauguration of a bicycle route across the United States. During the summer of 1976, 4,065 cyclists, who rode 10.4 million miles through 10 states on all types of roadways, served as a source of detailed information on riding habits, highway conditions, and accident experiences.

Throughout, and immediately following the event, stringent and probing records were kept of all accidents, providing Bikecentennial with a unique set of data to study the hazards of riding on shared roadways, and to learn ways to improve facilities, education programs, and enforcement in the future. This report is in response to the National Highway Traffic Safety Administration's Order Number NHTSA-7-3200, requesting a complete analysis of Bikecentennial's findings.


1.) Effective Class III Route Design Reduces Accidents. Bicyclists riding along the TransAmerica Bicycle Trail experienced only 50-75% of the accidents anticipated based on the number of accidents normally encountered in 10.4 million miles of exposure. In a study of proficient adult bicyclists by Jerry Kaplan (FHWA study of League of American Wheelmen bicyclists), a base rate of 113 accidents per million miles was established. In contrast, Bikecentennial riders experienced an average of 80 accidents per million miles. When riding off the trail, the accident rate often doubled, or even quadrupled. In a few states, where route selection was considered excellent, the accident rate dropped to lows of 29-35 accidents per million miles. Route design criteria leading to these low accident rates are included in the Appendix of this report.

2.) Accident Versus Non-Accident Rider Profile Established. By studying characteristics differentiating accident riders from non-accident riders, a typical profile was established for each. Youthful riders between 16-20 accounted for 41% of all accidents, although they only made up 27% of the population. Safety messages targeted to this group should be strengthened.

Accident Riders. This group rarely had a set plan of action for handling specific hazards, did not have a set riding technique, produced greater wear to their bikes and carriers, were less likely to obey traffic regulations, often rode alone, rarely wore bright clothing, and failed to make periodic safety checks of their bikes.

Non-Accident Riders. In contrast, this group typically was older (26 to 35 and 46 to 55) and married. They established definite riding technique, normally obeyed traffic regulations, always wore bright clothing, made periodic safety checks to their equipment, normally rode with care, and seldom needed to make any repairs.

3.) Bicyclists Need Set Plan of Action. As shown by the profile, bicyclists who have anticipated and developed plans for dealing with road hazards and other crises are much less likely to have an accident than those bicyclists who have not thought about or do not have established procedures for hazards. Practicing techniques such as emergency braking, abandonment of road, riding through a patch of gravel, and other hazard avoidance can reduce the frequency and seriousness of accidents.

4.) Accurate Accident Base Rates Established. On the average, a bicyclist using the TransAmerica Trail, or similar roadways, can anticipate having an accident requiring first aid treatment every 12,500 miles. An accident leading to a permanent injury can be anticipated every 250,000 miles and a fatality every 5.2 million miles. This report explores differing accident base rates, demonstrating how women, bicyclists carrying their own equipment, different age groups, and bicyclists using different portions of the trail have markedly different accident rates. These base rates allow a standard for future program or facility improvements in safety.

5.) Frequency of All Accident Causes Established. Due to the extreme accuracy of reporting, it was possible to establish the major and minor causes of all bicycle accidents common to this group. Motor vehicles were involved in 17.5% of the total accidents, and resulted in a 10% higher rate of injury seriousness. The single most frequent cause of accidents was one bicyclist running into another, producing 20% of all accidents.

A breakdown of the most common major accident causes appears as follows:

Bicyclist hit bicyclist


Pothole or broken pavement


Car hit bike


Loss of control


Bike crashed trying to miss car


Loose gravel on roadway


Rider fell off bike


Slipped on gravel road


6.) Downhills Are High Risk Areas. Between 50 and 75% of the accidents involving a bike hitting a hole, skid or crash, bike hitting animal, and loose gravel on pavement occurred on downhills. The majority of all lacerations and 80% of all fractures occurred on downhills. Improved highway maintenance on hilly terrain and extra caution on descents can dramatically reduce bicycle accidents. Cyclists should be made aware of the hazards of increased speed in all situations, and receive special training in braking techniques for high-speed descents.

7.) Road Condition Blamed for 27% of All Accidents. Bicyclists listed faulty roadway design or maintenance as the direct or indirect cause of roughly one out of four accidents. Major problems include potholes, broken pavement, steep road edge, loose gravel, and lack of signs or other warnings notifying users of hazards. Roadway design and maintenance is credited for primary reduction of accident rates in such states as Missouri and Montana (30 and 38 accident victims per million miles). In contrast, poor maintenance and design is largely responsible for the high accident rate in Kentucky (101.5 accident victims per million miles).

8.) Fatigue Contributes to Accidents. On the days bicyclists were scheduled to ride more than 75 miles, 75% of the accidents occurred after they had ridden 70 miles. Bicyclists should be cautioned on the hazard of pushing beyond safe limits.

9.) Equipment on Bike Dramatically Increases Accident Rate. Bicyclists who had their equipment transported for them had only a third the number of accidents of those riding fully loaded bicycles. Although this rate difference can be accounted for, in part, by the slightly different and older group of riders making up this group, this added equipment load stands out as a dramatic added safety risk and should be explored further.

10.) Educators/Students at Opposite Extremes in Safety Record. Educators comprised nearly 15% of all bicyclists on the TransAmerica Trail and held the greatest safety record. Students, who made up the greatest percentage of riders by class (34%), held the poorest safety record, perhaps associated with age. Study should be given to having educators who ride actively take special bicycle courses and teach bicycling in community education programs.

11.) Injury Types, Frequency, Severity Established. Scrapes and cuts occurred in 51% of all accidents. Other major injury types include 13.2% bruises, 7.2% lacerations requiring stitches, 4.9% sprains, 3.3% fractures, 3.3% concussions, and 11.8% miscellaneous injuries or combinations of injuries. Motor vehicle-related accidents resulted in a slightly higher percentage of serious injuries (50% requiring more than first aid as opposed to 40% average of all accidents). Hospital treatment was required in 28.5% of all accidents, and 5% of all accident victims were kept in the hospital overnight or longer. Permanent injuries were reported by 6.2% of all riders injured or .01% of all riders. Of these, roughly one out of four were serious enough to be considered disabling. There were two fatalities along the TransAmerica Trail, both resulting from an overtaking automobile.

12.) Most Accidents Go Unreported. As few as 10% of the bicyclists reported their accidents to law enforcement officials, and only 32% reported the accident to medical or insurance officials. Accidents most often reported include motor vehicle-related injuries and other injuries requiring more than first-aid treatment.

13.) Leaders and Groups Shift Nature and Seriousness of Accidents. The presence of trained leaders and small heterogeneous group involvement had the effect of lifting even inexperienced riders into an experience level normally achieved by cyclists who have been bicycling for five or more years. Group riding, with specific use of a buddy system, may have increased the number of bike/bike accidents but is felt to have reduced the risk of motor vehicle-related accidents and other more serious incidents.

14.) Improved Carrier, Pack, Bike Systems Needed. Although the lightweight, multigeared, ten-speed bicycle was proven to be particularly suited to the needs and requirements of the long-distance bicycle tourist, attention must be paid to design and selection of equipment. The nearly triple accident rate of those carrying equipment can be answered, in part, due to the need to alter bike requirements, and to use carriers and packs of superior design to those being commonly used today. Carriers and packs recorded failure rates of 14% and 15%, respectively. Bikes designed primarily for racing, of large frame size, and thin-gauge tubing are prone to a hazardous shimmy effect on fast downhill descents. Ill-designed carriers and packs create a whiplash effect, activating this shimmy, increasing the number and seriousness of downhill-related accidents. Additional study is suggested.

15.) Helmets, Bright Clothing, Safety Triangles, Accessories Can Reduce Frequency and Seriousness of Accidents. Bicyclists using helmets experienced a reduced number of head and facial injuries. In several instances, helmets are believed to have prevented serious or fatal concussions. It is estimated that 25% of the helmets carried on the trip were not in use while riding, due to inadequate ventilation. Bright clothing and safety triangles are credited in having reduced the frequency of motor vehicle-related accidents. Cyclists using rearview mirrors were not involved in any motor vehicle overtaking accidents.

16.) Motor Vehicle Air Blast or Suction Serious Cause Factor. Large vehicles traveling at high rates of speed can produce an air blast or suction knocking cyclists from roadway, or under vehicle. This factor is especially serious with small riders and on narrow roads with frequent crosswinds. Semi-trucks were involved in 50% of all such incidents.

17.) Shared Highway Use Compatibility Demonstrated. Although 54 bicyclists were injured (2 fatalities) through shared use of roadways, an unusually high degree of shared responsibility and courtesy dominated motorist and bicyclist behavior. Law enforcement officials and motorists mentioned incidents of some bicyclists causing traffic to back up. However, the predominant attitude was one of great cooperation, through proper use of bicycles, use of bright clothing, demonstrated courtesy, and helpful and friendly attitudes. In Eastern Kentucky, where heavy coal truck traffic could not be avoided, the two groups of users worked out effective communication systems (truckers used CB's to warn of bicyclist location); and there was extra courtesy on the part of the bicyclists.

18.) Laws, Rules of the Road, Local Enforcement. There is significant disparity between bicycling laws of different states or towns, causing confusion and noncompliance. Adherence of national uniform laws is suggested. Bicyclist behavior was tied to their understanding of what is right and wrong in shared highway use, based on gut feelings, respect, and desire for acceptance. Officials seeking compliance with specific laws issued warnings to bicyclists, which has positive but often local effect. Law enforcement officials are reluctant to arrest bicyclists, due to lack of support at the judiciary level. This failure appears to weaken the entire enforcement and, hence, education efforts of local communities.

Concluding Remarks. Throughout the analysis of the event and study, we have been impressed with the tremendous potential for reducing accidents through the encouragement of preferred bicycle roads. By selecting and improving potentially popular bicycling corridors, initiating an effective education and enforcement program, we believe it is possible to reduce bicycling accidents in America by up to 50% of the current rate. Bicyclists must be alerted to the major causes of accidents, taught standard rules of the road and defensive riding techniques, and become aware of the importance of bright clothing, safety accessories, and correct use of equipment. This system must be backed up with greater uniformity in laws, stern enforcement, and judicial support. Bicycling safety in America must be viewed as a system.

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