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SECTION V
BICYCLE/MOTOR-VEHICLE ACCIDENTS:
PROBLEM TYPES AND
EDUCATIONAL COUNTERMEASURES

Part 2

[This long section has been divided into three parts
for Internet publication]

CLASS C PROBLEM TYPES: MOTORIST TURN -- MERGE/DRIVE THROUGH/DRIVEOUT

Problem Class C consists of five problem types that together accounted for 2.4% of the fatal cases and 18.7% of the non-fatal cases. The Class C problem types are listed in Table 16 along with the proportions of fatal and non-fatal cases classified into each problem type. All Class C accidents occurred as the motorist entered an uncontrolled roadway from a driveway, alley, or from a controlled leg of an intersection. Except for Problem Type 12, all the motorists stopped or slowed significantly at the junction before proceeding into the intersecting roadway. In nearly every case, the motorist entered the intersection without having observed the bicyclist who was approaching the junction. The motorist's failure to observe the bicyclist was often the result of the bicyclist's unexpected location -- on the sidewalk or on the wrong side of the roadway. Many of the bicyclists involved in Class C accidents observed the motor vehicle soon enough to have avoided the accident, but failed to initiate evasive action because of the erroneous assumption that they had been or would be observed by the motorist.


TABLE 16

PROBLEM CLASS C --
MOTORIST TURN-MERGE/DRIVE THROUGH/DRIVEOUT

    FATAL
(N=166)
NON-
FATAL
(N=753)
TYPE 8 MOTORIST TURN-MERGE: COMMERCIAL DRIVEWAY/ ALLEY --- 5.3%
TYPE 9 MOTORIST TURN-MERGE/DRIVE THROUGH: INTERSECTION CONTROLLED BY SIGN 1.2% 10.2%
TYPE 10 MOTORIST TURN-MERGE: INTERSECTION CONTROLLED BY SIGNAL --- 1.9%
TYPE 11 MOTORIST BACKING FROM RESIDENTIAL DRIVEWAY --- .8%
TYPE 12 MOTORIST DRIVEOUT: CONTROLLED INTERSECTION 1.2% .5%
TOTAL CLASS (N: FATAL = 4; NON-FATAL = 141) 2.4% 18.7%

The vast majority of collisions occurred shortly after the motorist accelerated from a stopped position. This fact accounts for the low incidence of fatalities for Class C accidents. When the motor vehicle struck the bicycle, the impact velocity was low and the bicyclist usually careened off the front of the motor vehicle. When the bicyclist struck the motor vehicle, the impact velocity was solely a function of the bicyclist's speed. Apparently, the bicycle speed was not often great enough to produce fatal injuries. Because of the low incidence of fatal accidents, Class C accidents must be considered less important than other types of accidents that account for fewer accidents but more fatal injuries.

PROBLEM-TYPE DESCRIPTIONS

Problem Type 8 (5.3% Non-Fatal; No Fatal)

All of the cases classified into Problem Type 8 occurred as the motorist was entering a roadway from a driveway that served one or more commercial establishments. In a slight majority of cases, the motorist was entering a street with four or more lanes (55%); most of the remaining cases occurred as the motorist was entering a two-lane street (40%). Only five percent of the cases occurred on a rural roadway. Ninety-three percent of the accidents occurred during the daytime; 88% occurred between 11:00 AM and 7:00 PM.

It was found that 82% of the motorists came to a complete stop at the roadway junction. Eighteen percent of the motorists slowed to a low speed when approaching the junction but failed to bring their vehicle to a complete halt before proceeding into the roadway. In every case of this type, the motorist failed to observe the approaching bicyclist even though it was judged that the search function was performed in a manner that would be considered normal for motorists in this situation. As is explained below, the reason for the motorist's failure to observe the bicycle was found to differ somewhat for each of the subtypes illustrated in Figure 15.

  • Bicyclist on sidewalk approaching from the right (32.5%) -- It was found that the motorist's view of the bicyclist was obstructed in over half of these cases. In the remaining cases, the motorist failed to search far enough along the driveway to observe the approaching bicyclist. Apparently, the motorists searched in a manner that they considered adequate to detect approaching pedestrians. That is, they judged that a pedestrian located more than a few feet from the driveway junction could not possibly arrive at the junction before they had passed, so considered it unnecessary to scan the sidewalk more than a few feet from the junction. Because of the search pattern of motorists in this situation, it is probable that the removal of visual obstructions would have little effect on the incidence of accidents of this type.

  • Bicyclist on roadway approaching from the right (30%) -- It was found that the motorist's view of the approaching bicyclist was obstructed in about 25% of the cases. In the remaining cases, the motorist failed to search in the bicyclist's direction because he did not expect a hazard to be approaching from that direction. This pattern was found to be particularly prevalent when the motorist was intending to make a right- hand turn. Again, it is unlikely that the removal of visual obstructions would effect a reduction in accidents such as these.


Figure 15

Illustration of Problem Type 8,
Motorist Turn-Merge: Commercial Driveway/Alley.

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(NOTE: The building was drawn in the above illustration to indicate that this type of accident occurs at the junction of a commercial rather than a residential driveway/alley. Although a building sometimes obstructed the operator's view in accidents of this type, buildings were not the most frequent type of obstructing object.)

  • Bicyclist on sidewalk approaching from the left (5%)--This variation of Problem Type 8 occurred so infrequently that it is not possible to draw valid inferences about the reasons for the motorist's failure to observe the approaching bicyclist. However, it is probable that the reasons are the same as for the cases in the next paragraph.

  • Bicyclist on street approaching from the left (22.5%)--In slightly over half of these cases, the motorist searched in the bicyclist's direction but failed to observe the bicyclist even though he was clearly visible and the lighting conditions were good. Apparently, the bicyclist's image appeared in the motorist's field of view (on motorist's retina) one or more times but was not consciously perceived. This phenomenon is sometimes referred to as "selective perception." In about one-fifth of the cases, the motorist's failure to detect the bicyclist was because of darkness, inadequate bicycle lighting, or both. In the remaining cases, the motorist failed to search in the bicyclist's direction. Surprisingly, not a single case was found in which the motorist's view of the bicyclist was obstructed.

  • Bicyclist in far lane approaching from the right (10%)--This variation of Problem Type 8 occurred infrequently. However, in every case of this type, it was found that the motorist searched in the bicyclist's direction but failed to observe him. Only one-fourth of the cases of this type occurred at night and involved inadequate bicycle lighting. Judging from the characteristics of the traffic context in which accidents of this type occurred, it seems reasonable to assume that information overload and/or attentional conflict would be contributing factors in a substantial number of cases. Information overload is particularly likely in cases in which the motorist was attempting to turn left across a busy multiple-lane roadway.

The finding that fewer sidewalk accidents occurred when the bicyclist was approaching from the motorist's left is a significant finding. There is no reason to expect that bicyclists ride on the sidewalk in one direction more frequently than another, so it seems reasonable to conclude that accident likelihood is less when the bicyclist is traveling in the same direction as traffic in the adjacent traffic lane. The apparent reason for this finding is that motorists must search almost 90 degrees to their left in order to check for traffic that may be approaching in the near traffic lane. Since the bicyclist is often only a few feet from the traffic lane, he is likely to be detected, even though the motorist is mainly concerned with checking for approaching motor vehicles.

The bicyclist's preview time was critically limited by a visual obstruction in about 15% of the cases. In all but one of these cases, the bicyclist was riding on the sidewalk. In 25% of the cases, the bicyclist failed to search in the direction of the motorist until an accident was imminent. In 60% of the cases, the bicyclist observed the motor vehicle early enough to have easily avoided the accident but proceeded with the assumption that the motor vehicle would not enter the roadway until he had passed. Many of the bicyclists reported that they temporarily slowed their speed until they observed the motorist scanning in their direction. The eye contact with the motorist led the bicyclist to assume that he had been detected by the motorist when, in fact, he had not.

The data revealed that the bicyclist's decision to ride facing traffic was based upon convenience rather than ignorance of the law. Every bicyclist was questioned about this matter, and every bicyclist reported that he knew -- before the accident occurred -- that it is unlawful to ride facing traffic.

Problem Type 8 involved bicyclists whose ages varied widely. The median age of the bicyclists was 15.4 years. Only five percent were seven years of age or younger, and five percent were 49 years of age or older. About 50% of the bicyclists were between 13 and 17 years of age.

Problem Type 9 (1.2% Fatal; 10.2% Non-Fatal)

Problem Type 9 was one of the two most frequently occurring problem types, but only 1.2% of the fatal accidents were classified into this problem type. The reason for this large difference, as was explained earlier, is the generally low motor-vehicle speeds and resultant impact velocities for accidents that occur in this manner. The nature of the accident-generation process for Problem Type 9 is highly similar to that defined above for Problem Type 8. The main difference is that all the cases in Problem Type 9 occurred at a signed intersection rather than at the junction of a roadway and a commercial driveway. For Problem Type 9, the bicyclist approached the junction on an uncontrolled leg of the intersection, and the motorist approached the junction on an orthogonal leg that was controlled by a stop sign (97%) or a yield sign (3%). Accidents of this type occurred in both urban and rural areas and occurred on a variety of roadway types. The characteristics of the uncontrolled roadways are as follows: (a) a two-lane urban street (46%), (b) an urban street with more than two lanes (43%), (c) a two-lane rural roadway (8%), and (d) a rural roadway with more than two lanes (3%). This type of accident typically occurred during the daytime, but a significant number (17%) occurred during darkness. Ten percent of the accidents occurred between 7:00 AM and 9:00 AM, and another 66% occurred between 12:00 PM and 8:00 PM.

Ninety-four percent of the motorists came to a complete stop before entering the intersection, and 95% of the motorists entered the intersection without having observed the approaching bicyclist. When the motorist observed the bicyclist before entering the intersection, the accident occurred because the motorist misjudged the bicyclist's intended path. Usually, the motorist incorrectly assumed that the bicyclist was going to turn before intersecting the intended path of the motorist. The reasons for the motorist's failure to observe the bicyclist before entering the intersection are described below, within the context of the four subtypes illustrated in Figure 16.


Figure 16

Illustration of Problem Type 9,
Motorist Turn-Merge/Drive Through: Intersection Controlled by Sign
.

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  • Bicyclist in near lane(s), approaching from the right (54%) -- Although not illustrated in Figure 16, about one-fifth of these cases involved a bicyclist who was riding on the sidewalk before entering the roadway. In the remaining cases, the bicyclist was in the roadway riding facing traffic. However, the reason the motorist failed to observe the bicyclist was the same for all of these cases; namely, the motorist failed to scan in the direction of the bicyclist because he did not expect a hazard to be approaching from that direction. In this context, the typical motorist searches to his right for traffic approaching in the far lanes and to his left for traffic approaching in the near lanes; motorists seldom search 90 degrees to their right because they have seldom, if ever, encountered a threat approaching from that direction.

  • Bicyclist in near lane(s), approaching from the left (22%) -- When the motorist failed to observe the bicyclist approaching from the left in the near lane, it was most often due to inadequate search or selective perception. However, about one-third of these cases occurred during darkness and involved a bicyclist with inadequate bicycle lighting.

  • Bicyclist in far lane(s), approaching from the right (16%) -- In these cases, the motorist's failure to observe the bicyclist was usually due to inadequate search, but about one-fourth of the cases occurred during darkness and involved a bicyclist with inadequate lighting.

  • Bicyclist in far lane(s), approaching from the left (8%) -- More than half of the accidents of this type occurred during darkness and involved a bicyclist with inadequate lighting. In the remaining cases, the motorist failed to search in the bicyclist's direction because he did not expect a hazard to be approaching from that direction.

In 13% of the cases, the bicyclist failed to search in the motorist's direction until it was too late to avoid the accident. The bicyclist proceeded through the intersection without searching because he knew he had the right of way and assumed vehicles on intersecting roadways would yield to him. However, in 83% of the cases, the bicyclist observed the motor vehicle soon enough to have easily avoided the accident. The bicyclist's failure to initiate evasive action was due to his faulty assumption that he had been or would be detected by the motorist, and that the motorist would remain stationary until he had passed through the intersection. Surprisingly, nearly all the bicyclists who were riding facing traffic observed the motor vehicle long before the collision. All of these bicyclists were aware that riding facing traffic was unlawful, but still assumed that they would be observed by the motorist. The faulty assumption that they would be detected by the motorist was also prevalent among bicyclists who were riding during darkness.

Problem Type 9 involved an older group of bicyclists than any problem type discussed previously. The median age of the bicyclists involved in this type of accident was 16.3 years, and few of the bicyclists were very young. For instance, it was found that less than five percent of the bicyclists were younger than ten years of age; slightly over 50% of the bicyclists were between 13 and 20 years of age.

Problem Type 10 (1.9% Non-Fatal; No Fatal)

Problem Type 10 occurred infrequently and is simple and straightforward to explain. In all cases of this type, the motorist came to a complete stop at a signalized intersection, searched for traffic approaching from the left in the near traffic lanes, and proceeded to make a right turn on red. In every case, the motorist failed to observe the bicyclist before entering the intersection. Figure 17 illustrates that 85% of the Type 10 accidents involved a bicyclist who was riding facing traffic. The motorist failed to observe the bicyclist because he did not search in the bicyclist's direction. In 86% of the cases, the bicyclist observed the motor vehicle but proceeded through the intersection with the faulty assumption that he had been or would be detected by the motorist.

Although the sample size was too small to provide an accurate indication of the age distribution of bicyclists involved in Type 10 accidents, it was found that the small number of bicyclists who were involved in this type of accident varied in age from ten years to over 70 years of age. Very young bicyclists are probably involved in this type of accident only infrequently because they seldom ride in the types of locations in which such accidents occur.


Figure 17

Illustration of Problem Type 10,
Motorist Turn-Merge: Intersection controlled by signal.

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Problem Type 11 (.8% Non-Fatal; No Fatal)

Accidents classified into Problem Type 11 occurred when a motorist backed from a residential driveway into the path of an approaching bicyclist (see Figure 18). All of the bicyclists were riding in the street, and only one bicyclist was riding facing traffic prior to the collision. The motorist's view of the bicyclist was degraded in every case. One-third of the accidents occurred during darkness; the motorist's view of the bicyclist was obstructed by vegetation or parked motor vehicles in all of the remaining cases.

One of the main reasons for including this problem type is to show the infrequency with which it occurs. Since bicyclists must encounter motor vehicles backing from residential driveways very often and since the motorist's view in this situation is often obstructed by external objects or parts of the motor vehicle's structure, one would expect that Type 11 accidents would occur quite frequently. However, the research findings showed that this type of accident occurs far less often than accidents in which motorists are exiting a driveway in a forward direction (Problem Type 8). Although the reason for this large difference is not known for certain, it seems reasonable to assume that bicyclists perceive backing vehicles as potential threats and seldom make the erroneous assumption that they have been detected by the driver of a backing vehicle. It is also possible that motorists recognize the hazardousness of this situation and exercise more caution when backing from a driveway than when exiting a driveway in a forward direction.


Figure 18

Illustration of Problem Type 11,
Motorist Backing from Residential Driveway.

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The age range of the bicyclists who were involved in Type 11 accidents varied from five to 25 years of age.

Problem Type 12 (1.2% Fatal; .5% Non-Fatal)

As is illustrated in Figure 19, Problem Type 12 occurred when the motorist passed through a stop sign without making any attempt to stop or slow. This type of accident occurred infrequently, but is likely to result in fatal injuries to the bicyclist when it does occur. No inferences can be made about the nature of the accident-generation process for this type of accident because of the small sample size. However, it is interesting to note that three out of four motorists in the non-fatal sample failed to observe the stop sign; the remaining motorist in the non-fatal sample was unable to stop because of faulty brakes. All of the fatal cases involved an intoxicated motorist.


Figure 19

Illustration of Problem Type 12,
Motorist Driveout: Controlled intersection.

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EDUCATIONAL COUNTERMEASURES FOR CLASS C PROBLEM TYPES

Bicyclists

It was found that 52% of all Class C accidents involved a bicyclist who was riding on the wrong side of the roadway (riding facing traffic). Nearly all bicyclists are aware that riding facing traffic is unlawful, so there is no need to educate bicyclists about the law. Some persons have suggested that bicyclists should be taught the techniques that are required to ride facing traffic in a safe manner. However, it is unlikely that it would be possible to teach bicyclists techniques that would be as safe as riding on the correct side of the roadway. Furthermore, it is probable that such training would serve to promote wrong-way riding and thereby increase the number of wrong-way riding accidents, even though the training reduced accident rate for this type of accident. For these reasons, it seems that the most effective alternative is to design a training program to curtail wrong-way riding. To be effective, the program must convince the bicyclists (and their parents) that riding facing traffic is a hazardous thing to do and that accident likelihood is increased greatly when a bicyclist chooses to ride on the wrong side of the roadway. At the same time, the bicyclists and their parents must be informed that riding on the correct side of the roadway will not lead to increased numbers of accidents if the bicyclist exercises reasonable caution in selecting where and when he will ride.

For every problem type in Class C, it was found that a large proportion of the bicyclists observed the motor vehicle early enough to have easily avoided the accident. This finding was the same regardless of the bicyclist's location and direction of travel. The relatively small number of cases in which the bicyclist failed to search in the motorist's direction were due mainly to the bicyclist's fundamental assumption that all intersecting traffic would yield to him. One means of preventing such accidents is to modify bicyclists' views about the infallibility of motorists. A safety-education program developed for bicyclists should teach them the typical search patterns of motorists in this type of traffic context, the limitations of the human visual system, and the types of accidents that occur because a motorist fails to observe a bicyclist that may be clearly visible. This information must be presented in a manner that will serve to modify bicyclists' assumptions that they have been or will be detected by motorists who are preparing to enter an uncontrolled roadway from a driveway or from a controlled leg of an intersection.

Many existing educational materials instruct both bicyclists and pedestrians to establish eye contact with a motorist before proceeding across a stopped motor-vehicle's path. This education is probably counterproductive; it suggests that the  bicyclist or pedestrian can safely assume that he has been detected by the motorist if he has established eye contact. This is a clearly invalid assumption that led to a substantial proportion of Class C accidents.

Many bicycling experts advocate riding in the center of the traffic lane rather than along the right-hand edge of the roadway. They claim that riding in the center of the traffic lane increases the chances of being observed by motorists who are preparing to enter the roadway from intersecting streets or driveways. Also, they argue that riding in the center of the lane provides a greater buffer zone between the bicycle's path and the position at which motor vehicles stop before entering the roadway. Thus, riding in the center of the traffic lane provides additional time for the bicyclist to initiate evasive action once it becomes apparent that a motor vehicle is going to enter the roadway. It is believed that the following important questions must be answered before it is possible to recommend that bicyclists be taught to ride in the center of the traffic lane.

  • Would riding in the center of the traffic lane increase the likelihood of detection by a margin that has practical significance?

  • Would riding in the center of the traffic lane increase the bicyclist's preview time by a margin that has practical significance?

  • How would traffic efficiency be affected if riding in the center of the traffic lane became a common practice?

  • Should riding in the center of the traffic lane be prohibited on some types of roadways and/or during certain time periods? If so, what types of roadways and what time periods?

  • Should young bicyclists and/or slow-moving bicycles be permitted to ride in the center of the traffic lane? If not, what is the cutoff age/speed?

  • Would riding in the center of the traffic lane increase the incidence of other types of bicycle/motor-vehicle accidents or the incidence of accidents involving two motor vehicles?

Motorists

An education and training program for motorists has the potential for reducing the incidence of most problem types within Class C. The main objective of an education program would be to increase the effectiveness with which motorists search when entering uncontrolled roadways from driveways or from a controlled leg of an intersection. It is particularly important to modify the typical search patterns of motorists such that they make a concerted effort to scan for wrong-way bicyclists and for bicyclists riding on the sidewalk. When designing a training program for motorists, care must be taken to avoid promoting wrong-way riding. For instance, motorist-training materials developed for presentation on public television -- and therefore observed by both motorists and bicyclists -- should always include a message that stresses the danger and illegality of wrong-way riding.

CLASS D PROBLEM TYPES: MOTORIST OVERTAKING/OVERTAKING-THREAT

Class D includes five problem types that occurred when (a) a vehicle overtook and collided with a bicyclist traveling in the same direction, or b) the threat of an overtaking motor vehicle caused the bicyclist to collide with an object that obstructed the path he would have taken if the obstruction had not been present. Class D does not include cases in which the bicyclist turned or swerved into the path of an overtaking motor vehicle.

Table 17 lists the problem types and subtypes for Class D and shows the proportion of fatal and non-fatal cases that were classified into each problem type and subtype. It can be seen in Table 17 that Class D accounted for nearly 38% of all fatal cases and that nearly one-fourth of all fatal accidents were classified into Problem Type 13. Since Class D accounted for only 10.5% of the non-fatal cases, it is clear that the likelihood of suffering fatal injuries is far higher for Class D accidents than for any other accident class. The high incidence of fatal injuries is mainly the result of the high speed of the motor vehicle on impact. About 45% of both the fatal and non-fatal accidents in Class D occurred in a rural area. It also was found that 56% of all rural accidents in the fatal sample and 31% of the rural accidents In the non-fatal sample were classified into Class D.


TABLE 17

PROBLEM CLASS D--MOTORIST OVERTAKING/OVERTAKING-THREAT

    SUBTYPE TYPE
FATAL NON-
FATAL
FATAL
(N=166)
NON-
FATAL
(N=753)
TYPE 13 MOTORIST OVERTAKING: BICYCLIST NOT OBSERVED     24.6% 4.0%
 
  • RURAL NIGHTTIME
9.0% 1.3%    
 
  • RURAL DAYTIME
5.4% .4%    
 
  • URBAN NIGHTTIME
8.4% 1.3%    
 
  • URBAN DAYTIME
1.8% 1.0%    
TYPE 14 MOTORIST OVERTAKING: MOTOR VEHICLE OUT OF CONTROL     4.2% .7%
TYPE 15 MOTORIST OVERTAKING: COUNTERACTIVE EVASIVE ACTION     2.4% 1.7%
TYPE 16 MOTORIST OVERTAKING: MOTORIST MISJUDGED SPACE REQUIRED TO PASS     1.8% 2.0%
TYPE 17 MOTORIST OVERTAKING: BICYCLIST'S PATH OBSTRUCTED     .6% 2.0%
 
  • BICYCLIST COLLIDED WITH OVERTAKING MOTOR VEHICLE
.6% .8%    
 
  • BICYCLIST COLLIDED WITH OBSTRUCTING OBJECT
--- .4%    
 
  • BICYCLIST COLLIDED WITH OPENING MOTOR-VEHICLE DOOR
--- .8%    
UN-
KNOWN
MOTORIST OVERTAKING: TYPE UNKNOWN     4.2% .1%
TOTAL CLASS (N: FATAL = 63; NON-FATAL = 79) 25.2% 6.0% 37.8% 10.5%

PROBLEM-TYPE DESCRIPTIONS

Problem Type 13 (24.6% Fatal; 4.0% Non-Fatal)

Although seven other problem types occurred more frequently than Problem Type 13, this problem type must be considered one of the most important because it accounted for nearly one-fourth of all fatal accidents in the sample -- three times as many as any other problem type. The distinguishing characteristic of Problem Type 13 is that the operator of the overtaking motor vehicle failed to observe the bicyclist until the vehicles were in such close proximity that successful evasive action was impossible. Fifty percent of the non-fatal accidents and 59% of the fatal accidents of this type occurred in a rural area. About three-fifths of the rural accidents and about one-half of the urban accidents occurred on a narrow, two-lane roadway with no rideable shoulder. Thus, about 60% of the Type 13 accidents occurred on a narrow, "rural-type" roadway with two traffic lanes and no rideable shoulder or sidewalk. This type of roadway context is depicted in the illustration of Problem Type 13 (see Figure 20).


Figure 20

Illustration of Problem Type 13,
Motorist Overtaking: Bicyclist Not Observed.

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Problem Type 13 is the only problem type for which nighttime accidents were more frequent than daytime accidents. It was found that 63% of the non-fatal accidents and 71% of the fatal accidents occurred during darkness.

The exact position of the bicyclist and motorist at impact was difficult to determine with sufficient precision to know whether the bicyclist was traveling too far to the left or the motorist was traveling too far to the right. In about 20% of the cases, it was clearly established that the motorist was traveling farther to the right than he should have been. In the remaining cases, neither the motorist's position nor the bicyclist's position was judged to be clearly abnormal; it is probable that both operators were slightly out of position when the collision occurred.

The interviews revealed that bicyclists tend to ride farther from the right-hand edge of the roadway during darkness than during the daytime. Because of the combined effects of darkness and inefficiency of the bicycle headlight (if any), bicyclists are unable to detect and dodge road-surface defects and debris that often are present along the extreme edge of the roadway. To avoid such hazards, bicyclists ride farther to the left where the roadway is usually swept clean by the draft of motor-vehicle traffic. Because of this practice, it is probable that most of the bicyclists involved in nighttime accidents on narrow roads were riding farther to the left than is safe on such roadways.

Since Problem Type 13 includes only the overtaking accidents in which the motorist failed to observe the bicyclist until too late to avoid the accident, the main question about this problem type concerns the reasons for the motorist's failure to observe the bicyclist. In nearly every case, the motorist's failure to observe the bicyclist was the result of one or more of the following factors: darkness, inadequate bicycle lighting, alcohol use by the motorist, and operator distractions. Since vehicle speeds are usually considerably faster on rural than on urban roadways, the type of location can also be considered a contributing factor for this problem type. The reasons for the motorist's failure to search can be most meaningfully described by subdividing Problem Type 13 into the following subtypes:

  • Rural nighttime (9% fatal; 1.3% non-fatal). For this subtype, the motorist's failure to observe the bicyclist must be explained in terms of the relatively high speed of the motor vehicle, darkness, inadequate bicycle lighting, and alcohol use by the motorist. It is interesting to note that one-third of the fatal accidents of this type involved a motorist who had been drinking; none of the non-fatal accidents involved an intoxicated motorist.

  • Rural daytime (5.4% fatal; .4% non-fatal). The motorist's failure to observe the bicyclist must be explained in terms of high motor-vehicle speeds, alcohol use by the motorist, and search failures by the motorist due to momentary distractions. Again, it is of interest to note that one-third of the fatal cases, but none of the non-fatal cases, involved an intoxicated motorist.

  • Urban nighttime (8.4% fatal; 1.3% non-fatal). The factors contributing to the motorist's failure to search in this situation are essentially the same as for rural nighttime accidents, except that high motor-vehicle speed is not a factor. Like rural nighttime accidents, urban nighttime accidents often involved alcohol use by the motorist. An intoxicated motorist was involved in 43% of the fatal cases and eight percent of the non-fatal cases.

  • Urban daytime (1.8% fatal; 1.0% non-fatal). This subtype occurred so infrequently that it is not possible to draw valid inferences about the motorist's failure to search. However, it is almost certain that the motorist's attention was temporarily distracted from the roadway ahead shortly before the collision.

The above findings can be summarized by saying that it is dangerous to ride in rural areas at any time and it is dangerous to ride during darkness at any location, but accident likelihood is increased even more when riding in a rural area during darkness.

It is interesting to note that about 60% of the bicyclists who were involved in nighttime accidents had lawful taillights on their bicycles when the accident occurred. This finding suggests that the standards that have been established for bicycle rear reflectors are inadequate under some circumstances. In establishing standards for taillights, the question is not how far away a motorist can observe the rear reflectors under optimal conditions, but what is required to attract a motorist's attention under non-optimal conditions. For instance, what type of taillight would be required to attract the attention of a fatigued drunk driver who is traveling at a relatively high speed on a rural roadway where he does not expect to encounter a bicyclist? It is probable that this type of accident will continue to occur until a device is developed that will increase the nighttime conspicuity of the bicycle to such an extent that the previously described motorist will detect and identify the bicyclist most of the time.

Few young bicyclists were involved in Type 13 accidents. For example, it was found that the age of the 5th centile bicyclist in the fatal and non-fatal samples was 12.9 years and 11.2 years, respectively. Apparently, bicyclists younger than 11 or 12 years of age are not permitted to ride during darkness and in the types of areas where Type 13 accidents occur. The median age was 18.3 years for the bicyclists in the non-fatal sample and 20.5 years for bicyclists in the fatal sample.

Problem Type 14 (4.2% Fatal; .7% Non-Fatal)

Problem Type 14 includes overtaking accidents that occurred because the motorist was unable to maintain control of his vehicle. The illustration of Problem Type 14, shown in Figure 21, is somewhat misleading in its suggestion that the motor vehicle was in an uncontrolled slide or spin prior to the collision. Although the motor vehicle was totally out of control in some cases, more often the motor vehicle veered too far to the right due to the motorist's inability to maintain precise control of the vehicle.


Figure 21

Illustration of Problem Type 14,
Motorist Overtaking: Motor Vehicle Out of Control.

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Alcohol use by the motorist was the main contributing factor in 71% of the fatal cases and 40% of the non-fatal cases. In these cases, it was judged that the motorist's capability was impaired to such an extent that he was unable to steer the vehicle along his intended path. These accidents would have occurred whether or not the bicyclist had been observed by the motorist. In the remaining cases, loss of control was due to vehicle failure, snow and ice on the roadway, or a prior collision with another motor vehicle. It might be expected that accidents of this type would occur most often on narrow roadways where the space is marginally adequate for both motor vehicles and bicycles. However, it was found that 86% of the fatal cases and all of the non-fatal cases occurred on an urban street with more than two traffic lanes. Although the preponderance of accidents on wide roadways may be an artifact due to the small number of Type 14 accidents in the sample, it seems safe to conclude that limited roadway width is not an important contributing factor for Problem Type 14. Twenty-nine percent of the fatal accidents and 40% of the non-fatal accidents occurred during darkness, but degraded visibility was not judged to be a contributing factor. The higher incidence of Type 14 accidents during darkness is simply because the number of intoxicated motorists on the roadway is greater at night than during the daytime.

The number of cases classified into Problem Type 14 was too small to define a bicyclist target group, but it seems reasonable to conclude that involvement in this type of accident would be totally independent of the age of the bicyclist. The small number of bicyclists involved in this type of accident varied in age from six to 17 years.

Problem Type 15 (2.4% Fatal; 1.7% Non-Fatal)

Problem Type 15 includes overtaking accidents that resulted from both operators misjudging the direction of the other operator's evasive action. In the typical case, the motorist observes the bicyclist ahead, riding close to the center of the traffic lane. As the motorist approaches the bicyclist from the rear, he honks his horn and swerves left to pass the bicyclist. Upon hearing the horn (or the sound of the overtaking motor vehicle in some cases), the bicyclist evades to the left with the assumption that the motor vehicle is going to pass on the right. In short, the bicyclist's evasive action counteracts the evasive action taken by the motorist. Although Figure 22 shows both operators evading to the left, there were some accidents of this type that occurred when both operators evaded to the right.


Figure 22.

Illustration of Problem Type 15,
Motorist Overtaking: Counteractive Evasive Action.

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More than three-fourths of the accidents of this type occurred in a rural area on a two-lane roadway (52%) or on a roadway with more than two lanes (25%). The remaining 23% of the accidents occurred on a two-lane urban street. All accidents classified into Problem Type 15 occurred during the daytime between noon and 8:00 PM.

This type of accident usually involved a juvenile bicyclist. The median age of the bicyclists was 12.3 years, and fewer than five percent were older than 16 years of age. Slightly over five percent of the bicyclists were younger than six years of age.

Problem Type 16 (1.8% Fatal; 2.0% Non-Fatal)

An overtaking accident was classified into Problem Type 16 only when there was clear evidence that the accident resulted from the motorist's misjudgment of the space required to overtake and pass the bicyclist. As is shown in Figure 23, the bicyclist usually was struck by the extreme right-fret portion of the motor vehicle. In 13% of the cases, the motorist misjudged the space and time required to scan behind and change lanes before closing on the bicyclist riding ahead. These accidents could easily have been avoided if the motorist had slowed his speed before scanning behind to determine if it was safe to change lanes: In the remaining cases, the motorist observed the bicyclist ahead and incorrectly concluded that there was sufficient space to overtake and pass the bicyclist without changing lanes. In some cases, the motorist was temporarily prevented from changing lanes; in other cases, the motorist could have changed lanes but did not deem it necessary to do so.


Figure 23

Illustration of Problem Type 16,
Motorist Overtaking: Motorist Misjudged Space Required to Pass.

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Type 16 accidents occurred on a variety of roadways, including: an urban two-lane street (29%), an urban street with more than two lanes (29%), a rural two-lane roadway (29%), and a rural roadway with more than two lanes (13%). All Type 16 accidents occurred during the daytime.

The age of the bicyclists involved in Type 16 accidents varied widely. The median age of the bicyclists for this problem type was 15 years; about five percent were younger than nine years of age and five percent were older than 42 years of age. Older motorists are clearly over-represented in this problem type. It was found that 25% of the motorists were older than 66 years of age and five percent were older than 86 years of age.

Problem Type 17 (.6% Fatal; 2.0% Non-Fatal)

The distinguishing characteristic of Problem Type 17 is that the bicyclist was confronted simultaneously with the threat of an overtaking motor vehicle and an object that obstructed the path that he otherwise would have followed. Reference to Figure 24 shows that the bicyclist in this situation sometimes collided with the overtaking motor vehicle and sometimes collided with the obstructing object. In 40% of the cases, the bicyclist collided with the overtaking motor vehicle while swerving around an obstruction in his path (parked motor vehicle, roadway defect, pole, etc.). The motorist in these accidents observed the bicyclist but misjudged the magnitude of the bicyclist's turn to the left. In 20% of the cases, the bicyclist collided with the rear of a parked motor vehicle that obstructed his path. Many accidents involving a parked motor vehicle probably go unreported.


Figure 24

Illustration of Problem Type 17,
Motorist Overtaking: Bicyclist's Path Obstructed.

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Forty percent of the Type 17 accidents occurred when the occupant of a parallel-parked motor vehicle opened the left-hand door into the bicyclist's path. Although some motorists reported that they searched to the rear for traffic, none observed the bicyclist prior to the collision. Similarly, the bicyclist failed to observe that the parked motor vehicle was occupied. The relative frequency with which bicycles collide with an opening motor-vehicle door may be higher in some areas than was found in this study. In an unreported study by the author, 931 traffic accident report forms from areas within five different states were studied. It was found that car-door-opening accidents accounted for 2.6% of all reported bicycle/motor-vehicle accidents. However, the frequency with which this type of accident occurs was found to vary widely from one area to another. For instance, in a sample of 220 reports from Washington, D. C., it was found that 6.4% of all reported bicycle/motor-vehicle accidents were car-door-opening accidents. Conversely, not a single car-door-opening accident was found among a sample of 184 bicycle/motor-vehicle accidents that occurred in Fairfax County -- an area located only a few miles from Washington, D. C. Based upon the information presently available, it is estimated that car-door-opening accidents account for between two and four percent of the accidents that occur in urban areas. The percentage would probably be highest in the central business districts where the number and turnover of parallel-parked motor vehicles is high.

Most Type 17 accidents occur in urban areas; 57% occur on an urban two-lane street and 29% on an urban street with more than two lanes. Only 14% occurred on a rural roadway. All accidents of this type occurred during the daytime.

Surprisingly, few very young bicyclists were involved in this type of accident. The median age of the bicyclists was 16.3 years; only five percent were younger than nine years of age. The interquartile range for Problem Type 17 accidents was 12.9 years to 23.2 years.

Motorist Overtaking, Type Unknown (4.2% Fatal; .1% Non-Fatal)

In 4.2% of the fatal cases and .1% of the non-fatal cases, the information on the traffic accident report form was sufficient to establish that the accident was an overtaking accident but was not sufficient to determine the motorist's function failure and, therefore, the specific problem type into which the case should be classified. About half of the accidents occurred at night and about half occurred in rural areas. From the information that was available for these accidents, it is probable that most of them would have been classified into Problem Type 13. If this assumption is correct, the proportion shown in Table 17 for fatal accidents represents an underestimate of the frequency with which Type 13 fatal accidents occur.

EDUCATIONAL COUNTERMEASURES FOR CLASS D PROBLEM TYPES

Bicyclists

With only a few exceptions, there is little that a bicyclist can be taught that would help him avoid Class D accidents once he has decided to ride where and when such accidents are most likely to occur. As a consequence, the primary objective of an education and training program for bicyclists should center on modifying the bicyclist's choice of where and when he will ride. Until more effective rear-lighting systems are available, bicyclists should be taught to minimize the amount of night riding they do on any type of roadway, but particularly night riding on rural roadways. Bicyclists must also be taught to be highly selective in choosing the type of rural roadways they will ride on, regardless of the lighting conditions that prevail at the time of their trip. Specifically, bicyclists should be taught to avoid riding on any type of rural roadway unless operating speeds are low and a rideable shoulder is present.

Ideally, bicyclists could be taught to monitor overtaking motor vehicles using a rear-vision device and to always evade to the shoulder when overtaking motor vehicles are observed. Although most overtaking accidents in rural areas would be avoided if bicyclists could be induced to follow this procedure, it is unrealistic to expect them to do so as a common practice. Such a procedure would become so tiresome that all the pleasure would be lost from bicycle touring.

Bicyclists must be taught to recognize situations in which the space is so limited that a motorist's misjudgment of the width of his vehicle might result in an overtaking accident. In some instances, the bicyclist can slow his speed enough that the motor vehicle and bicycle do not arrive at a bottleneck at the same moment. When traffic is heavy and the lateral space is limited for some distance, little can be done other than to avoid riding in such areas. Similarly, bicyclists should receive special instructions on how to behave when they must ride to the left of objects that obstruct the path along the right-hand edge of the roadway. When the street is narrow and there are many parked cars along its length, bicyclists should be taught to search the parked cars for occupants who may open the left-hand door of the parked motor vehicle.

In some instances, it may be safer to ride in the center of the traffic lane than to attempt to anticipate an opening motor-vehicle door. However, as was stated earlier, considerable study is required before it can be recommended that bicyclists be taught to ride in the center of the traffic lane.

Bicyclist's Parents

The objective of parental education would be to induce parents to prohibit their children from riding their bicycles in rural areas at any time, during darkness in any location, and on any type of roadway for which operating speeds are high and space is limited. Essentially, the parents should receive the same type of education as the bicyclists.

Motorists

It is unlikely that any type of training would increase the likelihood that motorists will observe bicyclists under the circumstances in which Type 13 accidents occur. However, it is possible that motorist training would serve to decrease the incidence of accidents that result from a motorist's misjudgment of the space required to overtake and pass a bicyclist and accidents that occur when a motorist opens the left-hand door of his motor vehicle into the path of a bicyclist.


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Contents copyright 1978,
AAA Safety and Educational Foundation
Republished with permission
Internet edition prepared by John S. Allen