Reducing Collisions Involving Bicycles

Executive Summary

Introduction

Bicycling has been a form of human transportation for hundreds of years and remains a healthy and enjoyable alternative to today's primarily automobile-centric transportation patterns. Before the invention of the automobile, the League of American Wheelmen led efforts to develop and improve America's roadways, leading to our modern system of roads and highways. Bicycle safety problems have a long history in the United Stated, dating back to 1896 when a motor vehicle collided with a bicycle on a New York City Street—the first recorded automobile crash. More than a century later, safety continues to be a primary concern for modern bicyclists, with the challenges of traffic congestion, increasing distances between destinations, larger vehicles, and higher speeds.

Bicyclists are recognized as legitimate roadway users. The Federal Highway Administration (FHWA) bicycle program provides guidance on numerous issues which include examples of statutory language emphasizing that bicyclists are part of the transportation system and concludes that bicyclists “should be included as a matter of routine” in the planning, design, and operation of transportation facilities (FHWA, 1999). The American Association of State Highway and Transportation Officials (AASHTO) notes that bicycle use is recognized as “a viable transportation mode,” and that “All highways, except those where cyclists are legally prohibited, should be designed and constructed under the assumption that they will be used by cyclists” (AASHTO, 1999). With any roadway facility a potential bicycle facility, it is important to understand and accommodate bicyclists.

The safety interests of bicyclists are sometimes in conflict with the interests of motorists. This conflict arises primarily from the substantially different characteristics of the two modes of transportation. Although bicycles can be ridden on most types of roads, the design interests of accommodating higher motor vehicle traffic volumes and speeds during peak hour congestion may create conditions that are less safe for bicyclists. This guide includes road treatments, countermeasures, and other options that support a balanced transportation system.

Safety concerns can significantly influence a person's decision to bicycle for transportation or recreation. Bicyclists inherently understand that they are vulnerable road users. However, understanding bicyclist safety issues has proven difficult for engineers, planners, and facility designers. Traditionally, safety problems have been identified by analyzing police crash reports, and improvements have been made only after crashes have occurred. Such methods are not sufficient to fully understand and effectively address bicyclist safety concerns; waiting for crashes before responding with countermeasures carries a high price because many bicycle crashes tend to be severe.

Bicycling has received increased attention in recent years as a mode of transportation that should be encouraged for a variety of reasons. In 1994, the U.S. Department of Transportation presented the National Bicycling and Walking Study (NBWS) to the U.S. Congress, which, in addition to documenting the state of bicycling and walking in the United States, contained two overall goals (USDOT, 1994b):

• Double the number of total trips made by bicycling and walking in the United States from 7.9 percent to 15.8 percent of all travel trips.
• Simultaneously reduce by 10 percent the number of bicyclists and pedestrians killed or injured in traffic crashes.

Congress adopted the Study's goals, effectively creating a directive to Federal transportation agencies to implement the Study's Nine-Point Federal Action Plan with 60 specific action items for the Office of the Secretary, Federal Highway Administration (FHWA), National Highway Traffic Safety Administration (NHTSA), and Federal Transit Administration (FTA); and a Five-Point State and Local Action Plan with a range of suggested activities for state and local agencies. In addition, Congress has vastly increased Federal funds available for bicycle-related projects with the adoption of ISTEA in 1991, TEA-21 in 1998, and SAFETEA-LU in 2005. Federal transportation spending on bicycling and walking increased from $6 million in 1990 to more than $422 million in 2003 (Raborn, 2004).

Progress has been made on the two NBWS goals. The goal of reducing injuries and fatalities by 10 percent has been surpassed. The number of bicyclist and pedestrian fatalities decreased by 18 percent from 1993 to 2003; bicyclist fatalities dropped by 23.3 percent. The number of bicyclists injured in collisions with motor vehicles decreased by 35.3 percent over the same time period (Raborn, 2004), but these decreases may reflect a downward trend in overall bicycling as much as they indicate safety improvements. Since 2003, however, these trends have reversed: as of 2005, the decrease in bicyclist fatalities from 1993 had decreased to less than 4 percent. So, progress has been made on reducing bicyclist injuries and fatalities, but that progress appears now to be eroding.

The NBWS goal of doubling the percentage of walking and bicycling trips has not been accomplished, although the number of trips increased and perhaps doubled. In 1990, there were an estimated 1.7 billion bicycling trips; in 2001, that number had almost doubled to 3.3 billion. Combined walking and bicycling trip numbers increased from 19.7 billion to 38.6 billion. The percentage of bicycle trips, however, increased a mere one-tenth of a percent (from 0.7 percent to 0.8 percent), while combined trips increased from 7.9 percent to 9.5 percent. The disparity between the large increase in trip numbers and the small increase in trip percentages can be explained by the explosive growth in total reported trips of all modes; from 249 billion in 1990 to 407 billion in 2001 (Raborn, 2004).

With current Federal policies and guidance and the resources now available to improve conditions for bicycling, any agency charged with construction, operation, and maintenance of transportation infrastructure must devote attention to accommodating safe bicycling activity. The trends show that progress is indeed being made to meet the national walking and bicycling goals, but opportunities remain to improve facilities and programs for bicyclists.

Statement 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 I-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.

EXHIBIT I-1
Bicyclist fatalities from 1995–2005 (NHTSA, NCSA, Traffic Safety Facts 2004 Data: Pedalcyclists, from FARS data)

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 I-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 I-2
Bicyclist injuries from 1995 to 2005 (NHTSA, NCSA, 1995–2004; data from GES estimates)

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 types of crashes that were most severe were parallel path, rather than crossing path, crashes. Crossing path crashes occur at junctions (intersections or driveways) and more often in urbanized areas where speeds are often slower. Crash type severity was measured by the percentage of bicyclists involved in each type of crash that were seriously injured or killed, as shown below:

Crossing paths