Reducing Collisions Involving Bicycles

Type of Problem Being Addressed

General Description of the Problem

Since the nationwide peak of 1,003 bicyclist fatalities reported in 1975 in the Fatality Analysis Reporting System (FARS), traffic-related bicyclist fatalities and injuries have trended downward. Over the past 10 years, the number of fatalities has generally trended downward, although the most recent 2 years have shown a clear increase (see Exhibit III-1). The NHTSA National Center for Statistics and Analysis (NCSA) reports that fatalities have been from 2 to 25 percent below the number killed in 1995 (830 bicyclists) for 8 of the 10 years, even while all motor vehicle crash fatalities have shown increases since 1995. In 2005, 784 bicyclists (5.5 percent below the 1995 level) were killed in collisions with motor vehicles, an increase of 8 percent from 2004 and nearly 27 percent from the 10-year low of 622 bicyclist fatalities recorded in 2003. The 2005 number represented about 2 percent of those killed in all motor vehicle crashes for the year, a proportion that has remained relatively constant in recent years.

A total of 45,000 bicyclists were estimated injured nationwide in crashes with motor vehicles in 2005, which represents an increase in both the number of bicyclists injured and the proportion of all traffic injuries (2 percent) from 2004 (NHTSA, NCSA, from General Estimates System [GES], Exhibit III-2). Reported injuries do not include crashes not reported to the police, even if the bicyclist may have been injured, but this figure likely captures most serious roadway crashes involving motor vehicles. While the number of bicyclist injuries and fatalities fluctuates from year to year, potentially reflecting economic conditions, variations in weather, riding exposure, and other trends, as well as chance variation, the general downward trends have been good news. The recent increases in fatalities over the past 2 years, however, dramatically reinforce the need for adoption of strategies to reduce collisions involving bicyclists.

EXHIBIT III-1
Bicyclist Fatalities from 1995–2005 (NHTSA, NCSA, Traffic Safety Facts 2005 Data; Bicyclists and Other Cyclists, from FARS Data)

EXHIBIT III-2
Bicyclist Injuries from 1995 to 2005 (NHTSA, NCSA, 2005; Data from GES Estimates)

The NBWS published in 1994 stated goals of doubling the percentage of total trips made by bicycling and walking while concurrently reducing the number of bicyclists killed or injured in traffic crashes by 10 percent. The “Ten Year Status Report” released in October 2004 indicates that bicycling trips increased from 1.7 billion, representing 0.7 percent of all trips in 1990, to 3.3 billion (0.9 percent mode share) in 1995, more than doubling the number in 5 years (based on Nationwide Personal Transportation Surveys data). The estimates may not be completely comparable since new interviewing techniques were introduced with the 1995 survey that may have captured more trips. The number of trips remained static, however, from 1995 to 2001 (from 2001 National Household Travel Survey [NHTS] data), with the mode share decreasing from 0.9 to 0.8 percent by 2001. Data from the U.S. Census Journey to Work survey indicate that the number and percentage of people riding bicycles to work declined from 1990 to 2000. The increase in bicycle trips suggested by the NHTS data may therefore be due mostly to increases in other utilitarian and recreational trips (Raborn, 2004).

Although the bicycle percentage of all trips has not doubled over the past 10 years, the fact that numbers of injuries and fatalities and fatality rates per population have decreased over this general time period (see Exhibit III-3), while the number of bicycling trips has increased, is good news. The proportions of these declines that are due to improved safety of roadways and other facilities and improvements in the skill and behavior of bicyclists and motorists, or that may be due to changes in the type of riding and exposure such as the relative amounts or locations of riding by child and adult riders, is unknown because detailed exposure data for bicyclists are lacking. There are indications of possible changes in exposure by different age groups. For example, not only have adult cyclists accounted for an increasing proportion of bicyclist fatalities in recent years as the older population has increased, but the fatality rate per population for adults aged 35 and above has been increasing, while the fatality rate for children has been decreasing.

To continue toward the goals of increasing bicycling and walking trip share, states and communities are increasingly focusing on efforts to support active transportation and recreation. There are multiple reasons to improve opportunities for bicycling, including the health and fitness of community members, decreased motor vehicle congestion, and improved air quality. Some population groups, such as those with a lower income, may also depend heavily on bicycling for basic transportation. Children should also be able to safely bicycle to school. Communities have an obligation to provide safe access for all populations. Therefore, states and communities are tasked with improving safety and reducing the numbers of bicyclists killed and injured on our roadways while encouraging and increasing opportunities for bicycling.

EXHIBIT III-3
Fatality Rates per Million Population for Years 1994 and 2004, and Injury Rate per Million Population, 2004 (NHTSA, Traffic Safety Facts, 1994–2004 Data)

States and Local Areas with the Highest Numbers of Crashes

Bicyclist fatalities and fatality rates tend to vary from year to year as well as by state and local jurisdiction. In 2005, the total bicyclist fatality rate across the United States was 2.64 per million population. Exhibit III-4 provides bicyclist fatality rates for the 50 states, the District of Columbia, and Puerto Rico. On average, bicyclists accounted for approximately 2 percent of all fatalities resulting from motor vehicle crashes in 2005. This proportion has remained relatively constant in recent years.

Factors Affecting the Number and Severity of Crashes

Bicyclists' and motorists' behaviors as well as roadway, traffic, and light conditions, many of which are discussed below, are among the factors that may contribute to bicycle crashes. Specific bicyclist and motorist maneuvers that may lead to crashes are identified in the Precipitating Events section.

Alcohol Involvement
Alcohol or other impairment is a significant factor for overall crashes and crash severity. For all crashes, nearly 11 percent of drivers were reported to be under the influence of alcohol, drugs, or medication, and alcohol was involved in 40 percent of fatalities (NHTSA, 2004). Alcohol use is also over-represented in bicyclist fatalities. Alcohol use by either the motorist or the bicyclist was reported in more than one-third of the fatal bicyclist collisions over the past 3 years (NHTSA, n.d.). In 30 percent of the 2005 crashes, either the motorist or bicyclist had a blood alcohol concentration (BAC) of 0.08 g/dl or higher. Over one-fifth (23 percent) of bicyclists killed had a BAC of 0.08 g/dl or higher and 27 percent had a BAC of 0.01 g/dl or higher.

EXHIBIT III-4
Bicyclist Traffic Fatalities and Fatality Rates by State, 2005 (Source: NHTSA, 2005; FARS Data; Population Data from Bureau of the Census)

Night Riding
According to the NCSA, 31 percent of bicyclist fatalities occurred between the hours of 5 and 9 p.m. (NHTSA, 2004 data). A sample of crashes from six states from the early 1990's found that 15 percent of crashes occurred under conditions of darkness (lighted and unlighted roadways) and another 5 percent at dusk or dawn. Additionally, serious injury and fatal crashes were disproportionately likely to occur during late night (10 p.m. to 2 a.m.) and early morning (2 a.m. to 6 a.m.) hours. Alcohol was also more likely to be a factor.

Data from the 6,951 North Carolina bicycle/motor vehicle crashes reported over 7 years indicate that 20 percent of the crashes occurred under conditions of darkness with another 5 percent at dusk or dawn (see http://www.pedbikeinfo.org/pbcat/). Serious and fatal injuries were also over-represented in North Carolina night-time crashes, particularly on unlighted roadways. The differences in crash seriousness between lighted and unlighted roadways may be largely related to other factors such as speed limit and urban (more often lighted) and rural (often unlighted) locations.

While most states have laws requiring the use of head and tail lights at night, review of crash reports reveals that many bicyclists involved in night-time crashes (4.4 percent) did not use the required equipment (Hunter et al., 1996). Better crash report information would likely raise this figure further. Additionally, requirements vary from state to state, and in some cases, the required lighting may not improve visibility sufficiently.

Wrong-way and Sidewalk Riding
Bicyclists who ride against the direction of traffic or on the sidewalk are implicated in crashes occurring along the roadway. In a study of a representative sample of 2,931 bicycle crashes from six states (California, Florida, Maryland, Minnesota, North Carolina, and Utah) prepared for FHWA in the early 1990's, bicyclists were riding against the direction of traffic in 32 percent of relevant cases and about 15 percent of bicyclists were coded as contributing to the crash by riding against traffic (Hunter et al., 1996). This factor is particularly prevalent in crashes at intersections and other junctions where the motorist and bicyclist are on crossing paths. Bicyclists riding the wrong-way are approaching from a direction where motorists do not expect them, and motorists are typically looking for a gap to the left before pulling out. The right-turn-on-red vehicle movement is an additional component to a number of these crashes. Additionally, bicyclists traveling the wrong-way may not be able to see traffic signs and signals.

Bicyclists on the sidewalk are also in a position where motorists do not expect them, particularly if also traveling the wrong-way. While about 16 percent of the cases indicated the bicyclist was riding on the sidewalk, riding off the sidewalk at a driveway or intersection was indicated as a factor in a little more than 9 percent of the cases analyzed by Hunter et al. (1996). Crashes involving sidewalk riding tended, however, to result in fewer serious and fatal injuries than other crashes. Around 10 to 11 percent of the North Carolina crashes involved sidewalk riding. Three-fourths of bicyclists riding on a sidewalk, crosswalk, or driveway crossing in these crashes were also riding facing traffic. The problem is further compounded since bicyclists are often traveling faster than pedestrians and may not have enough time to avoid a vehicle pulling across the sidewalk.

Traffic Speed
Speed influences both the severity of crashes that occur as well as the likelihood of occurrence, and has been identified as a contributing factor in all types of crashes. National data suggest that 31 percent of crashes were speed-related. Driving too fast for conditions or in excess of posted speed limit or racing was identified as a contributing factor for drivers in 30 percent of all fatal crashes in 2005 (NHTSA, 2005 data). Fatality rates are also higher for crashes on higher speed limit roadways, climbing from about 2 per 1,000 crashes at speeds of 48 km/h (30 mph) or less to more than 14 per 1,000 at 88 km/h (55 mph) or more. Fatal bicyclist injuries were more than six times as prevalent, and disabling injuries were nearly twice as prevalent, than for all bicyclist crashes in North Carolina when excessive speed was indicated. Bicyclists are vulnerable road users, and the impact of higher speeds on crash severity is obvious.

Parking and Driveways
The number of potential conflict areas increases when driveways are frequent or closely spaced and on-street parking is provided. Bicyclists are particularly vulnerable to left-turning motorists who may not observe approaching bicyclists before making left turns into driveways or side streets. Serious injury can also occur when bicyclists ride too close to parked vehicles. Motorists exiting a parked vehicle without checking behind may open a door or step out in front of a bicyclist. “Dooring” crashes are related to presence and configuration of on-street parking and adjacent travel or bike lanes. In a study conducted by Hunter et al. (1996), bicyclist-side, on-street parking was present in nearly 12 percent of crashes.

Helmet Use
While helmets may not have an impact on the frequency of crashes, numerous studies have found that use of approved bicycle helmets significantly reduces the risk of fatal injury, serious head and brain injury, head injury, and middle and upper face injury among bicyclists of all ages involved in all types of crashes and crash severities. Relative risk reductions estimated in a meta-analysis of 16 peer-reviewed studies were 60 percent for head injury, 58 percent for brain injury, 47 percent for facial injury, and 73 percent for fatal injury (Attewell et al., 2001).

Where Crashes Occur

Area type
The majority of bicycle/motor vehicle crashes occur in urban areas, typically around two-thirds but varying with population densities and other factors, reflecting the greater populations and more frequent riding that typically occur in urban areas. In 2005, 69 percent of bicyclist fatalities nationwide also occurred in urban areas (NHTSA, 2005 data). However, rural crashes do tend to be more serious, reflecting higher speed roads and types of crashes that occur in rural areas, and result in a higher proportion of fatal and serious injuries (Exhibit III-5). In North Carolina, rural crashes accounted for 34 percent of all crashes over a recent 3-year period but comprised 53 percent of the fatal injuries and 57 percent of the disabling injuries.

EXHIBIT III-5
Bicyclist Injury Distributions for Rural and Urban Crash Locations, 2000–2003, North Carolina Bicycle/Motor Vehicle Crashes. (Source Data NCDOT/PedBike Division)

Location Type
Nearly one-half of all bicycle traffic crashes occurred at intersections, another 4 percent were intersection-related, and driveways and other junctions accounted for about 22 percent of crashes in the FHWA study (Hunter, et al., 1996). About one-fourth of crashes occurred at non-intersection locations with no distinguishing features. Data from North Carolina crashes found that about 42 percent occurred at intersections or were intersection-related. More fatal bicyclist crashes tend to occur at non-intersection locations (70 percent), while the majority of injury crashes (62 percent) occur at intersections (NHTSA, Traffic Safety Facts, 2003 and 2005).

Road Type
The types of roads on which crashes occur likely vary from state to state. In the FHWA study, crashes occurred most frequently on local streets (34 percent), followed by county routes (28 percent), state routes (18 percent), U.S. routes (8 percent), and Interstate routes (0.2 percent). Other road types accounted for 13 percent of bicyclist crashes (Hunter et al., 1996).

When Crashes Occur

Bicycle crash frequencies are generally highest during the summer and lowest in the winter, but these trends may vary by region of the country, depending on general climate, rainfall, and other factors.

Crashes fluctuate by day of the week year-to-year but are generally fairly evenly distributed, with somewhat fewer occurring on weekend days than week days.

Various data sources indicate that crashes peak in the afternoon to early evening hours. In the Hunter et al. study (1996), the peak number of crashes occurred between the hours of 2 and 6 p.m. (41 percent). The second highest crash period was between the hours of 6 and 10 p.m. (25 percent). By contrast, only 9 percent of crashes occurred between the 4-hour periods of 6 to 10 a.m. NHTSA data mirror these time-of-day trends but also suggest that fatalities are over-represented in the later evening. More bicyclists were injured between the hours of 3 and 6 p.m. (31 percent), but the highest period for fatalities was between 6 and 9 p.m. (23 percent of fatalities) (NHTSA, 2003).

Nearly 96 percent of crashes occur during clear or cloudy weather when most riding is likely to occur, while about 4 percent of crashes occurred while it was raining (Hunter et al., 1996). Mirroring weather conditions, most crashes occur on dry roadways (92 percent), with about 7 percent occurring on wet roads and 1 percent under other conditions.

Characteristics of the Victims

Although declining in recent years, the fatality and injury rates among child riders, in particular the 10- to 15-year-old age group, remain the highest per capita among any age group (Exhibit III-3), and about one-fifth of bicyclist traffic fatalities were between the ages of 5 and 15 in 2004. The share of fatalities accounted for by those under age 16 has been declining in recent years, however, from 37 percent in 1994 to 21 percent in 2004 (NHTSA, 1994–2004 data).

Both the number and the proportion of fatalities among adults ages 35 and up has been increasing, from 36 percent of all bicyclist fatalities in 1994 to 59 percent in 2004. Crashes involving adult bicyclists ages 25 and up tend to be more serious, resulting in fatal and disabling injuries a higher percentage of the time. These trends may be due in part to where adults ride and the types of crashes in which they tend to be involved.

Males of all ages account for the largest proportion of injured and killed bicyclists (76 percent and 87 percent in 2004, respectively), and the rates of injury and death are 3.4 times and 6.8 times those of females. These trends tend to hold up in various locations and jurisdictions and other data generally indicate that males account for around 70 to 80 percent of riders in most locations.

As mentioned previously, alcohol use on the part of the bicyclist may be a factor in about 20 to 25 percent of bicyclist fatalities.

Child bicyclists are deemed to be solely at fault 70 to 80 percent of the time in crashes with motor vehicles, while only about 40 percent of adult bicyclists are deemed to be at fault (Hunter et al. 1996). Both bicyclist and motorist are identified as contributing to the crash in 5 to 20 percent of crashes over various bicyclist ages. Motorists were deemed to be solely at fault in from 5 percent of crashes with the youngest aged cyclists to about 36 percent of crashes involving adults ages 50 to 59.

Precipitating Events

Crashes involving bicycles and motor vehicles are complex phenomena, and classifying the different events into mutually exclusive categories is a formidable task. Cross and Fisher (1977) were the first researchers to develop and apply crash ‘typology' for bicycle crashes as part of a NHTSA response to the 1,003 bicyclist fatalities in 1975. NHTSA also developed a coder's handbook for typing bicyclist crashes to address this issue (NHTSA, n.d.).

Similar typology was used in the FHWA study by Hunter et al. (1996). In a six-state study of 3,000 bicycle crashes taken from hard copy police reports, the most frequent bicycle/motor vehicle crash types were as follows:

Crossing Path Crashes

% of All Crashes

  • Motorist failed to yield to bicyclist
        (includes drive out/through at intersections and at Midblock/driveway locations)
  • 21.7
  • Bicyclist failed to yield to motorist at an intersection
  • 16.8
  • Bicyclist failed to yield to motorist, midblock
  • 11.8
  • Other crossing path crashes
  • 7.2
    Total % 57.5


    Parallel Path Crashes

    % of All Crashes

  • Motorist turned or merged into bicyclist's path
  • 12.2
  • Motorist overtaking bicyclist
  • 8.6
  • Bicyclist turned or merged into motorist's path
  • 7.3
  • Other parallel path crashes
  • 7.4
    Total % 35.5


    Specific Circumstances Crashes

    % of All Crashes

    (such as off-roadway, backing vehicle, intentional, and other unusual crash types). 7.0

    Crash type proportions varied by state, however, likely reflecting differences in urbanization and other characteristics.

    The most severe crashes, as measured by the percentage of involved bicyclists seriously injured or killed, were as follows:

    Crossing paths

  • Bicyclist turning error (23.8 percent)
  • Bicyclist failed to yield, midblock (22.1 percent)
  • Bicyclist failed to yield, intersection (20.1 percent)

    Parallel paths

  • Operator loss of control (34.6 percent)
  • Wrong-way operator (most often the bicyclist) (32.1 percent)
  • Motorist overtaking (29.4 percent)
  • Bicyclist turn/merge into the path of a motorist (25.2 percent)

    The high proportions of severe crashes, therefore, were all parallel path crashes. Crossing path crashes occur at junctions (intersections or driveways) and more often in urbanized areas where speeds are often slower.

    Children tend to be over-represented more often in crossing path crashes including ride outs at non-intersection locations (such as driveways) and at intersections, failing to clear an intersection, and turning errors, and in turn/merge maneuvers in front of motorists traveling on parallel paths. Adults tend to be over-represented in parallel path crashes (which tend to be more severe) including motorist overtaking crashes, motorist turn/merge in front of bicyclist on a parallel path, as well as in bicyclist overtaking motorist crashes.

    The crash typologies developed by Cross and Fisher, by NHTSA, and in the FHWA study evolved into the development of an automated crash typing software, the Pedestrian and Bicycle Crash Analysis Tool (PBCAT) (Harkey et al., 1999), which is currently being further refined for version 2. These and other studies have resulted in the identification of a number of specific crash types that have been classed into thirteen groups (plus an additional miscellaneous group comprising non-roadway, and some rarer and unusual crash types) for the purposes of identifying appropriate countermeasures. The definitions of these crash groups are shown in Exhibit III-6.

    EXHIBIT III-6
    Example Bicycle/Motor Vehicle Crash Types and Descriptions
    Crash GroupExample Image
    1. Motorist failed to yield — signalized intersection

    Description — The motorist drove into the crosswalk area or intersection and collided with the bicyclist. The motorist either violated the signal or did not properly yield right-of-way to the bicyclist.

    2. Motorist failed to yield — nonsignalized intersection

    Description — The motorist drove into the crosswalk area or intersection and collided with the bicyclist. The motorist either violated the sign (stop, yield, flashing signal) or did not properly yield right-of-way to the bicyclist.

    3. Bicyclist failed to yield — signalized intersection

    Description — The bicyclist rode into theintersection and collided with the motorist. The bicyclist either violated the signal or did not properly yield right-of-way to the motorist.

    4. Bicyclist failed to yield — non-signalized intersection

    Description — The bicyclist rode into the intersection and collided with the motorist. The bicyclist either violated the sign (stop, yield, flashing signal) or did not properly yield right-of-way to the motorist.

    5. Motorist drove out — midblock.

    Description — The motorist drove across the sidewalk or into the street from a nonintersection location (including residential or commercial driveway or other midblock location) without yielding to the bicyclist.

    6. Bicyclist rode out — midblock.

    Description — The bicyclist rode into the street from a non-intersection location (including residential or commercial driveway or other midblock location) without yielding to the motorist.

    7. Motorist turned or merged left into path of bicyclist.

    Description — The motorist made a left turn or merge into the path of a bicyclist traveling in the same or opposite direction.

    8. Motorist turned or merged right into path of bicyclist.

    Description — The motorist made a right turn or merge into the path of a bicyclist traveling in the same or opposite direction.

    9. Bicyclist turned or merged left into path of motorist.

    Description — The bicyclist made a left turn or merge into the path of a motor vehicle traveling in the same or opposite direction.

    10. Bicyclist turned or merged right into path of motorist.

    Description — The bicyclist made a right turn or merge into the path of a motor vehicle traveling in the same or opposite direction.

    11. Motorist overtaking bicyclist

    Description — The motorist was overtaking the bicyclist at the time of the crash.



    12. Bicyclist overtaking motorist

    Description — The bicyclist was overtaking the motorist (passing on the right or the left) at the time of the crash. (Includes crashes involving bicyclists striking parked cars or extended doors.)

    13. Non-motor vehicle crashes.

    Description — These crashes do not involve a motor vehicle and may occur in a variety of ways including bike only falls, bike-bike, bike-pedestrian, and bike into object crashes.

    14. Other and non-roadway crashes

    Description — Includes a variety of specific crash types such as turning errors by the bicyclist or motorist, head-on crashes resulting from the bicyclist or the motorist traveling in the wrong lane, intentional crashes, other unusual crashes, and crashes occurring in parking lots, driveways, and other off-roadway areas.