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.
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.
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.
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 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.
Parking and Driveways
Where Crashes Occur
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.
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:
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:
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.