Public Health Bicycling and Cycling Safety
by
Rebecca L. Sanders, Jill F. Cooper
  • LAST REVIEWED: 15 June 2015
  • LAST MODIFIED: 30 January 2014
  • DOI: 10.1093/obo/9780199756797-0092

Introduction

The topic of bicycle safety has been treated differently in the United States than in other Western countries and less motorized countries. In the western European countries, where bicycling for transportation has been popular for decades, safety has also been a primary concern, with an emphasis on creating a safe environment for cyclists. In more auto-dominant countries like the United States and the Commonwealth countries, however, land use patterns designed to facilitate automobile travel have led to generally unsafe and unpleasant environments for utilitarian cycling. Instead of examining the role of motor vehicles and roadway design in perpetuating the danger, there has tended to be a focus more on the danger of cycling itself—and cycling has, until recently, been left as an aside to transportation planning. Recently, given the public health, fiscal, and environmental benefits of bicycling, it has been enjoying increased popularity in many countries around the world, and with this increased popularity has come a renewed focus on safety. In less motorized countries, cycling remains popular; however, with the recent growth of private vehicle ownership, safety concerns have arisen. This bibliography outlines many of the research studies on the various aspects of bicycling safety. Works were selected after conducting searches for the terms “(bi)cycle/ing safety,” “(bi)cycle/ing risk,” “(bi)cycle/ing injury(ies),” “bicycle helmets,” “(bi)cyclist visibility,” and “(bi)cycle/ing facilities,” using Google Scholar™, PubMed™, and the Transportation Research Board Bicycle Committee’s Bicycle Research Database, in addition to the authors’ own exposure to works presented and cited at public health and transportation conferences. Selections were generally limited to peer-reviewed studies in reputable journals in the fields of transportation, public health, and medicine, among others, and reports from well-known organizations in these fields; however, a few non-peer-reviewed sources are included for emerging areas of research. In general, the authors have attempted to describe results, as well as limitations to the works selected. While seminal works from earlier decades are included, the focus of this review is on recent literature, in order to most accurately include current information and thinking about cycling safety. The review attempts to include a range of perspectives on the many facets of bicycle safety, but it does not intend or claim to be comprehensive; indeed, it is intended as a starting point for readers interested in bicycling safety, and the authors hope that exploration of the sources included here will lead to additional exploration through the reference lists of these texts. Readers will be able to use this outline to access sources on the nature of bicycle crashes, such as injuries and the severities of crash types; populations involved in bicycle crashes; factors contributing to bicycle crashes; the role of infrastructure in encouraging or detracting from bicycle safety; the relationship between objective and subjective bicycle safety; protective cycling equipment; and efforts to mitigate bicycle crashes.

General Overviews

The works in this section provide a thorough look at the various aspects of bicycling safety. There is no authoritative text on bicycling safety, given that it has tended to be discussed and studied less than the safety of other transportation modes. However, anyone looking for a brief overview of bicycling safety would do well to start with these sources. Toroyan, et al. 2009, published by the World Health Organization, gives an international perspective on bicycling safety, with a look at less motorized countries. Krizek, et al. 2009 presents a thorough report on bicycling research from around the globe, including the effects of policies, studies on bicycle safety and specific facilities, and research on larger issues of preferences, land use, and urban design. Swanson and Milne 2012, the biennial Bicycling and Walking in the United States Benchmarking Report issued by the Alliance for Biking & Walking, is an outstanding source of information about bicycling safety, policies, funding, advocacy efforts, benefits, mode share data, and more for the fifty United States. The 15-year status update of the National Bicycling and Walking Study (Pedestrian and Bicycle Information Center 2010) reports on progress toward the original 1994 study’s goals in the United States. Jacobsen and Rutter 2012, the chapter on Cycling Safety in City Cycling (based in part on a literature review, Jacobsen, et al. 2009, cited under Macrotrends in Cycling Risk) presents a higher-level view of issues regarding cycling safety and how they fit with other aspects of bicycling, such as its contribution to public health and environmental goals. Cleven and Blomberg 2007, the NHTSA Compendium gives an overview of nearly forty years of research conducted by the Office of Behavioral Safety Research. The web page of the Bicycle Transportation Research Subcommittee of the Transportation Research Board contains a downloadable database of bicycling research, while the website of the Pedestrian and Bicycle Information Center contains a breadth of information about bicycling in general as well as bicycling safety.

Journals

Because bicycling safety is a niche subject, there are no journals dedicated exclusively to its exploration. However, aspects of bicycling safety are frequently studied and written up in several scholarly, peer-reviewed journals. These journals are most often related to public health or medicine, such as Accident Analysis & Prevention, Injury Prevention, the American Journal of Epidemiology, and the Journal of the American Medical Association. Other journals cover topics in transportation, including Transportation Research Record, Transport Policy, and Transportation. There are also occasional articles in planning and urban design journals, such as the Journal of the American Planning Association.

Statistical Sources for Cycling Risk

There are several valuable resources for examining bicycling crashes, particularly in the United States. The National Highway Traffic Safety Administration (NHTSA) publishes an annual Traffic Safety Facts report (see National Highway Traffic Safety Administration 2013), which provides summary statistics of bicycling safety in the United States. The NHTSA also keeps data on traffic crashes linked to its website through the Fatality Analysis Reporting System, which can be analyzed online or downloaded for research. Also on a national level, Hunter, et al. 1996 is a report on a large sample of bicycle crash types and characteristics, providing an idea of how bicycle crash risk is distributed among different crash types. Several states capture data on bicycle crashes, but arguably the most accessible format is California’s Transportation Injury Mapping System, which offers ten years of reported bicycle crashes for the entire state, with multiple tools for analysis. At the more local level, many cities maintain crash data on public websites. Profiled here are data and reports from the New York City Department of Transportation and the San Francisco Municipal Transportation Agency, which make great efforts to publish bicyclist exposure and crash data, as well as accompanying reports. Finally, no crash reports should be viewed without a healthy dose of skepticism: in a comparison of police reports to hospital records, Stutts and Hunter 1998 found that less than 50 percent of bicycle crashes captured via hospital visit had an accompanying police crash report.

  • Hunter, W. W., J. C. Stutts, W. E. Pein, and C. L. Cox. 1996. Pedestrian and bicycle crash types of the early 1990’s. FHWA-RD-95-163. McLean, VA: Office of Safety and Traffic Operations Research & Development, Federal Highway Administration.

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    This report examined a sample of three thousand bicycle crashes, using the NHTSA bicyclist crash typologies to develop a refined estimate of crash type distributions for bicycle crashes. The report includes information on bicyclist and driver characteristics, fault, temporal and environmental factors, roadway factors, crash characteristics, and locational characteristics. Technical Summary also available online.

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    • National Highway Traffic Safety Administration. Fatality Analysis Reporting System.

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      The NHTSA Fatality Analysis Reporting System (FARS) is an annual nationwide census of fatal injuries caused by motor vehicle traffic crashes. Queries can be run through the website or the data can be downloaded for analysis.

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      • National Highway Traffic Safety Administration. 2013. Traffic safety facts 2011. Washington, DC: National Highway Traffic Safety Administration.

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        In addition to maintaining a website about bicycling safety that includes toolkits, educational materials, and an abundance of links to related bicycle safety efforts, NHTSA publishes yearly analysis of bicycling safety facts for the fifty states. Reports dating back to 1994 are available on the NHTSA website.

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        • New York City Department of Transportation. Bicycling Statistics.

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          The NYC DOT keeps both bicycling counts and crash data available on its website for downloading and analysis. In addition, the DOT maintains a Cycling Safety Indicator that describes changes in cycling safety.

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          • San Francisco Municipal Transportation Agency. Bike Reports.

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            The SFMTA produces annual reports on bicycling and bicycling safety in the city, all downloadable from its website. Some of the reports detail specific projects, while others focus on cycling overall, such as the currently quadrennial San Francisco State of Cycling Report (the 2012 report is also available online.

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            • Stutts, J. C., and W. W. Hunter. 1998. Police reporting of pedestrians and bicyclists treated in hospital emergency rooms. Transportation Research Record 1635:88–92.

              DOI: 10.3141/1635-12Save Citation »Export Citation »E-mail Citation »

              The authors compared crash reports for bicyclists with emergency room hospital records for eight hospitals in New York, California, and North Carolina. Only 48 percent of the bicycle hospital cases were matched to crash files. Hospitalization or death made one 1.4 times more likely to have an associated crash report.

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              • Transportation Injury Mapping System.

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                The Transportation Injury Mapping System, or TIMS, is a joint project between the California Office of Traffic Safety and the Safe Transportation Research and Education Center at UC Berkeley. The site contains the most recent ten years of reported crash information, including geocoding, for the entire state of California.

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                Macrotrends in Cycling Risk

                This section includes literature on the bigger picture of cycling risk. This topic includes comparisons on the national level to bicycling safety in other countries, comparing bicycling within the United States, and examining trends in cycling risk, such as the concept of “safety in numbers,” which finds that the risk of cycling injury decreases as more people bicycle. The section includes Jacobsen, et al. 2009, a broad literature review of the effects of motorized traffic on safe and enjoyable walking and bicycling. Pucher and Dijkstra 2003 compares bicycling risk in the United States to that in the Netherlands and Germany, concluding that the United States is far from being considered as safe a place to bicycle. Marshall and Garrick 2011 examines how higher levels of bicycling safety may reflect dynamics in a community, concluding that cities that are safer for cyclists are safer for all road users. Pucher, et al. 2011 examines bicycling safety between the United States and Canada, including a case study of nine large cities, and finds that targeted efforts do in fact make a difference for cycling and cycling safety. Jacobsen 2003 found evidence of “safety in numbers” through an analysis of injury rates and bicycle commute data in multiple cities in California and Denmark, as well as at the national level for countries in Europe. Robinson 2005 also found evidence of “safety in numbers” through an analysis of Australian data. Elvik 2009 reviewed several “safety in numbers” studies and found evidence that the nonlinearity of risk is real, but that there are thresholds at which it operates.

                • Elvik, R. 2009. The non-linearity of risk and the promotion of environmentally sustainable transport. Accident Analysis and Prevention 41:849–855.

                  DOI: 10.1016/j.aap.2009.04.009Save Citation »Export Citation »E-mail Citation »

                  The author analyzed the results of multiple “safety in numbers” studies to determine thresholds for the effect with regard to transferring motorized trips to bicycling and walking. His analysis found that risk of transferring trips is nonlinear, although he cautions that additional study is needed to better understand it.

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                  • Jacobsen, P. L. 2003. Safety in numbers: More walkers and bicyclists, safer walking and bicycling. Injury Prevention 9:205–209.

                    DOI: 10.1136/ip.9.3.205Save Citation »Export Citation »E-mail Citation »

                    The author examined pedestrian and bicyclist injuries and mode share and trip data for four different analyses: 68 cities in California, 14 European countries, 8 European countries, and 47 Danish towns. In each case, he found an exponential decrease in the number of injuries as the amount of bicycling increases.

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                    • Jacobsen, P. L., F. Racioppi, and H. Rutter. 2009. Who owns the roads? How motorised traffic discourages walking and bicycling. Injury Prevention 15:369–373.

                      DOI: 10.1136/ip.2009.022566Save Citation »Export Citation »E-mail Citation »

                      A review of public health, city planning, public administration, engineering, and medical literature exploring how motor vehicle traffic creates an unsafe and unpleasant environment for walking and bicycling, and thus discourages people from doing so.

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                      • Marshall, W. E., and N. W. Garrick. 2011. Evidence on why bike-friendly cities are safer for all road users. Environmental Practice 13.1: 16–27.

                        DOI: 10.1017/S1466046610000566Save Citation »Export Citation »E-mail Citation »

                        The authors compared the safety of bicycling, walking, and driving in twenty-four cities with varying levels of bicycling mode share in California. They found that crashes in the bicycling-friendly cities had lower injury severity levels for all road users, which they attributed to street network density as well as a higher percentage of nonmotorized travel.

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                        • Pucher, J., R. Buehler, and M. Seinen. 2011. Bicycling renaissance in North America? An update and re-appraisal of cycling trends and policies. Transportation Research Part A 45:451–475.

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                          This article compares trends in cycling demographics, amounts, safety, trip purposes, and funding in the United States and Canada. It includes case studies of nine large cities in the two countries. The authors found that cycling has experienced much growth and support, although seemingly only in certain places.

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                          • Pucher, J., and L. Dijkstra. 2003. Promoting safe walking and cycling to improve public health: Lessons from the Netherlands and Germany. American Journal of Public Health 93.9: 1509–1516.

                            DOI: 10.2105/AJPH.93.9.1509Save Citation »Export Citation »E-mail Citation »

                            The authors examined fatality, injury, and trip data for cyclists in the Netherlands, Germany, and the United States. They found that bicyclists in the United States have a much higher fatality and injury rate than the other two countries. The article includes policy recommendations for increasing cycling safety.

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                            • Robinson, D. L. 2005. Safety in numbers in Australia: More walkers and bicyclists, safer walking and bicycling. Health Promotion Journal of Australia 16:47–51.

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                              The author examined data for the fatalities and amounts of cycling in Australia in the 1980s; fatality and injury rates over time; and serious injuries and fatalities before and after Victoria instituted a helmet law. She found evidence that risk per kilometer falls as cycling increases, and vice versa.

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                              Objectively Measured Risk

                              Any discussion of bicycling safety will necessarily be divided between multiple topics, including objective and subjective risk. Research on objective risk includes studies comparing the risk of bicycling to other modes. There are various metrics for comparison, including time-based, distance-based, and trip-based. Beck, et al. 2007 compared the safety of several modes on a per-trip basis and found that bicycling was the third most dangerous, after traveling by motorcycle and special (nonpassenger car) vehicle. Arguing that time-based risk is more appropriate than trip-based risk, Guler, et al. 2012 used county travel survey data to calculate risk-per-hour of car, SUV, transit, bicyclist, and pedestrian travel, finding that bicycling was the most dangerous per hour of travel. Joshi, et al. 2001 used trip diaries to investigate not only risk of collisions, but also the risk of a “near miss” on a per-mile basis. The data suggests that bicycling and walking are more dangerous than travel by car, bus, and motorcycle for both categories. Other research on objective risk examines the crash injury and severity of bicycle crashes in depth in order to understand details about how the crashes occur and who is affected. These studies may be conducted using publicly available crash data, hospital data, or insurance data. For example, Kim, et al. 2007 used crash data to investigate bicycle crashes in North Carolina and found that cyclists were more likely to be seriously injured or killed in crashes with motor vehicles when the motor vehicle was traveling above 30 mph, it was dark outside, the bicyclist was intoxicated, or the bicyclist was at fault, among other things. Bíl, et al. 2010 also found that cyclists in the Czech Republic were more likely to be seriously injured or killed when the motorist was speeding, although in this study, the cyclist was more likely to be seriously injured or killed when the motorist was at fault. Rivara, et al. 1997 used hospital data to investigate seriously injured bicyclists, finding that such injury was more likely from crashes involving a motorist, higher cyclist speed, and younger or older age. Helmet use was not associated with serious injury in any direction. Isaksson-Hellman 2012 analyzed insurance claims about bicycle crashes with motor vehicles and found that the insurance data, at least in Sweden, is quite detailed and can supplement analyses using crash or hospital records.

                              • Beck, L. F., A. M. Dellinger, and M. E. O’Neil. 2007. Motor vehicle crash injury rates by mode of travel, United States: Using exposure-based methods to quantify differences. American Journal of Epidemiology 166.2: 212–218.

                                DOI: 10.1093/aje/kwm064Save Citation »Export Citation »E-mail Citation »

                                The authors of this paper used national-level travel survey and injury data to calculate the risk-per-trip of passenger cars, other vehicles, motorcycles, pedestrians, and bicyclists. They found that although motorcycles were the most dangerous, bicycling was more dangerous than either walking or traveling by passenger car on a per-trip basis.

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                                • Bíl, M., M. Bílova, and I. Müller. 2010. Critical factors in fatal collisions of adult cyclists with automobiles. Accident Analysis and Prevention 42:1632–1636.

                                  DOI: 10.1016/j.aap.2010.04.001Save Citation »Export Citation »E-mail Citation »

                                  The authors used traffic records from the Czech Republic to identify the main factors associated with serious bicycle–motor vehicle crashes for adult cyclists. Multivariate regression revealed that fatal crashes are more likely a motorist’s fault, fatally injured cyclists are more likely to be men, and the probability of death increases with age.

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                                  • Guler, S. I., O. Grembek, and D. R. Ragland. 2012. Using time-based metrics to compare crash risk across modes and locations. Berkeley: Univ. of California Berkeley Safe Transportation Research and Education Center.

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                                    The authors compared the traffic risk of various modes using risk-per-hour of travel. In contrast to a trip-based metric, time-based risk recognizes the varying speeds, and therefore varying amounts of exposure, of different travel modes. The authors found that, on a per-hour basis, bicycling is more dangerous than traveling by any other mode.

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                                    • Isaksson-Hellman, I. 2012. A study of bicycle and passenger car collisions based on insurance claims data. Annals of Advances in Automotive Medicine 56:3–12.

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                                      This study used insurance data to reconstruct 438 bicycle–motor vehicle crashes from 2005 to 2010 in Sweden. The author found that the insurance data can supplement crash and hospital records to identify factors contributing to a crash, although this approach requires controlling for exposure.

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                                      • Joshi, M. S., V. Senior, and G. P. Smith. 2001. A diary study of the risk perceptions of road users. Health, Risk & Society 3.3: 261–279.

                                        DOI: 10.1080/13698570120079877Save Citation »Export Citation »E-mail Citation »

                                        This article is based on trip diaries from 291 road users in Oxford, including pedestrians, car and bus drivers, bicyclists, and motorcyclists. The findings suggest that bicyclists and pedestrians experience many more incidents (near-misses or collisions) per mile than motorcyclists, car, or bus drivers, making their journeys much more risky overall.

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                                        • Kim, J.-K., S. Kim, G. F. Ulfarsson, and L. A. Porrello. 2007. Bicyclist injury severities in bicycle-motor vehicle accidents. Accident Analysis and Prevention 39:238–251.

                                          DOI: 10.1016/j.aap.2006.07.002Save Citation »Export Citation »E-mail Citation »

                                          This study used multinomial logit modeling to examine motor vehicle–bicycle crashes of all injury levels from 1997 to 2002 in North Carolina. The authors found several factors significantly associated with a bicyclist fatality, including older age of bicyclist, intoxication of either party, higher vehicle speed, heavy truck involvement, inclement weather, and darkness without streetlights.

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                                          • Rivara, F. P., D. C. Thompson, and R. S. Thompson. 1997. Epidemiology of bicycle injuries and risk factors for serious injury. Injury Prevention 3:110–114.

                                            DOI: 10.1136/ip.3.2.110Save Citation »Export Citation »E-mail Citation »

                                            This study examined serious injuries from nearly four thousand bicycle crashes over a three-year period in the Seattle area. Risk of serious injury was increased by collision with a motor vehicle, speed of bicyclist, and young (< 6 years) or older (> 39 years) age, but not affected by helmet use.

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                                            Population Differences in Cycling Risk

                                            Serious discussions about cycling safety must take into account the extent of cycling and cycling crashes among different populations. In this section, we explore some of the special populations that surface during reviews of cycling safety. While data on the relative safety of special populations is rare, studies exist that present perceived safety and preferences, frequencies of crashes among specific populations, and barriers to engaging in cycling. The populations presented do not cover the range of special populations affected, but are reflected in studies and governmental reports found in the literature. Studies and reports focus on the following groups: women, children and teens, older adults, Hispanic communities in the United States, alcohol-impaired cyclists, and road users in less motorized countries. Jacobsen and Rutter 2012 and Sibley 2010 discuss how women perceive cycling risk. Issues related to cycling in traffic, transporting groceries and children, crime, and commuting are included. Bernhoft and Carstensen 2008 surveyed adults aged 40–49 and adults aged 70 and over to discern any age and gender differences in perception of safety and safety behaviors. Knoblauch and Seifert 2004 discusses safety among the large, and growing, Hispanic communities in the United States. Adolescent risk taking and effective approaches for addressing risk-taking behavior are addressed in Feenstra, et al. 2010. Dellinger and Staunton 2002, a study released through the US Centers for Disease Control and Prevention (CDC), discusses traffic risk and encouraging active transit to schools. Crocker, et al. 2010 examines the consequences of bicycling under the influence of alcohol. Large cities, or megacities (primarily in countries in Latin America, Africa, and Asia), contain the majority of the world’s population and are experiencing rapid growth. While private vehicle ownership in many countries has been limited, hence the term “less motorized countries,” the availability of inexpensive vehicles and the growth of population is making vehicle ownership more popular and accessible. This mode share increase holds negative consequences, not only for safety, but also for the environment and air quality. Mohan and Tiwari 2000 discusses the issues relevant to safety and mobility in these countries.

                                            • Bernhoft, I. M., and G. Carstensen. 2008. Preferences and behaviour of pedestrians and cyclists by age and gender. Transportation Research Part F 11:83–95.

                                              DOI: 10.1016/j.trf.2007.08.004Save Citation »Export Citation »E-mail Citation »

                                              Authors examined results from a survey of older adults on perceived traffic risk and on behavior in Denmark. Left-hand turning behavior, stopping at red lights, using cycling paths, and cycling on the correct side of the street were explored. Women were found to be more likely than men to doubt their cycling capabilities in traffic.

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                                              • Crocker, P., O. Zad, T. Milling, and K. A. Lawson. 2010. Alcohol, bicycling, and head and brain injury: A study of impaired cyclists’ riding patterns R1. American Journal of Emergency Medicine 28.1: 68–72.

                                                DOI: 10.1016/j.ajem.2008.09.011Save Citation »Export Citation »E-mail Citation »

                                                Data about alcohol and helmet use and crash involvement was collected in emergency rooms. Impaired cyclists were less likely to use helmets, were less responsive to road hazards, and were less likely to have medical insurance.

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                                                • Dellinger, A. M., and M. D. Staunton. 2002. Barriers to children walking and biking to school—United, States, 1999. Morbidity and Mortality Weekly Report 51:701–704.

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                                                  Concerns about the lack of physical activity among children have focused on how to encourage walking and bicycling to school. A survey given to school-aged children (5–18) revealed barriers such as distance, weather, traffic dangers, crime danger, and opposing school policies.

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                                                  • Feenstra, H., R. A. C. Ruiter, and G. Kok. 2010. Social-cognitive correlates of risky adolescent cycling behavior. Public Health 10.408: 1–7.

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                                                    The authors report that adolescents aged 13–18 years involved in bicycle accidents did not report that they became safer cyclists, holding implications for programming. This study took place in the Netherlands.

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                                                    • Jacobsen, P. L., and H. Rutter. 2012. Cycling safety. In City cycling. Edited by J. Pucher and R. Buehler, 141–156. Cambridge, MA: MIT Press.

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                                                      The authors discuss the relative risk faced by female cyclists. While data do not show that women are at greater traffic crash risk than men while bicycling, they do reveal that women perceive greater traffic risk than men, resulting in lower inclination to cycle. Reasons for perceptions are given.

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                                                      • Knoblauch, R., and R. Furst Seifert. 2004. The pedestrian and bicyclist highway safety problem as it relates to the Hispanic population in the United States: Final report. FHWA Report DTFH61-03-P-00324. McLean, VA: Federal Highway Administration.

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                                                        Crash data show that pedestrian and bicycle injuries among Hispanic populations in the United States are overrepresented. A literature review conducted as part of the report indicates that Hispanic men are significantly overrepresented in bicycle fatalities, as are adult cyclists aged 21–29. Bicycling while alcohol-impaired is a concern, as well.

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                                                        • Mohan, D., and G. Tiwari. 2000. Mobility, environment and safety in megacities: Dealing with a complex future. International Association of Traffic and Safety Sciences Journal 24.1: 39–46.

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                                                          With the increased mode share of private vehicles in developing countries, the authors recommend placing emphasis on understanding the safety and mobility consequences on altering transportation and land when making planning decisions. The importance of segregated bicycle lanes are discussed for removing conflicts between vehicles and buses.

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                                                          • Sibley, Anna. 2010. Women’s Cycling Survey: Analysis of results. Greensboro: Univ. of North Carolina at Greensboro.

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                                                            The author reports results from an online questionnaire examining women’s perspectives about cycling for transportation. While the research presents a unique focus on women and cycling, the results are based on a snowball, rather than systematic, sample. In evaluating safety concerns of women cyclists, distracted driving was cited as the driver behavior with which most female cyclists were concerned.

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                                                            Bicycling Risk in Separated Spaces

                                                            Studies related to separate roadway space for bicyclists have taken the form of research on striped bicycle lanes, grade- or barrier-separated cycle tracks, and side paths (sidewalks are covered below under Bicycling Risk in Shared Spaces). Although these facility types differ in many ways, it is also true that within each category there is a range of facility quality, with some being objectively safer than others. This has contributed to much contention about whether to separate bicyclists from motor vehicles, as low-quality, narrow facilities may be a risk to the cyclist, in contrast to high-quality, well-marked, separated facilities that provide visibility, predictability, and space. The issue is further complicated by the fact that many cyclists, from potential to frequent, desire to ride in separated space, as seen in several of the surveys profiled in the Route Choice and Environment and Subjectively Measured Risk sections of this bibliography. However, there are also bicyclists (known as “vehicular cyclists”) who prefer to ride in traffic lanes with cars. This group successfully fought against bicycle facilities in US cities for years because of a fear of being required to ride in what they deemed substandard spaces. Forester 2001 uses data like the Santa Barbara study (see Cross 1974) to argue that separating bicycles does not fix current bicycling safety issues—in fact, Forester argues, it makes them worse. Recently, however, research has shown that separated bike facilities can and often do confer general safety benefits, not the least of which is that they tend to attract more riders, which increases bicyclists’ visibility on roadways (the “safety in numbers” concept, discussed under Macrotrends in Cycling Risk). Chen, et al. 2012 found that bike lanes in New York City were associated with no statistical increase in bicycling crashes—even without accounting for increased exposure. In a meta-analysis of studies on bicycle facilities, Reynolds, et al. 2009 found that, overall, bicycle facilities were positively associated with increased cycling safety. Jensen’s Copenhagen model (Jensen 2008) predicted that cycle tracks did increase crash risk, but Jensen did not account for changes in exposure. The case-crossover study of bicycle routes in Teschke, et al. 2012 found a significantly decreased risk of bicycling crashes associated with cycle tracks in Vancouver and Toronto. Similarly, Lusk, et al. 2011 found that cycle tracks in Montreal had a lower relative risk of bicycle injury than parallel roadways.

                                                            • Chen, L., C. Chen, R. Srinivasan, C. E. McKnight, R. Ewing, and M. Roe. 2012. Evaluating the safety effects of bicycle lanes in New York City. American Journal of Public Health 102.6: 1120–1127.

                                                              DOI: 10.2105/AJPH.2011.300319Save Citation »Export Citation »E-mail Citation »

                                                              Chen and colleagues used generalized estimating equations to conclude that new bicycle lanes in New York City did not lead to increased crashes, despite the likely increase in bicyclists along the route. While this study controlled for some typically confounding factors, the failure to control for exposure lessens its impact.

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                                                              • Cross, K. D. 1974. Identifying critical behavior leading to collisions between bicycles and motor vehicles. Santa Barbara, CA: Anacapa Sciences.

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                                                                The author categorized bicycle crash data by crash type, movement, and fault. He found that most bicycle crashes occur at junctions or due to wrong-way travel of bicyclists, and that crashes caused by same-direction travel were relatively few. This paper has been cited as evidence that separated facilities do not address bicycle safety.

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                                                                • Forester, J. 2001. The bicycle transportation controversy. Transportation Quarterly 55.2.

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                                                                  More of an opinion piece than a scholarly article, this piece presents a leading vehicular cyclist’s perspective on why bicycling in the roadway is safer than using bicycling facilities. The article includes an anecdotal account of Forester’s experience bicycling in the road versus on a parallel sidepath.

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                                                                  • Jensen, S. U. 2008. Bicycle tracks and lanes: A before-and-after study. Paper presented at the 87th Annual Meeting of the Transportation Research Board, 13–17 January 2008.

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                                                                    Jensen evaluated the safety of cycle tracks in Copenhagen via a prediction model based on what crash statistics would have been had no changes occurred. He found that cycle tracks increased crashes, although the model did not properly account for cyclist exposure.

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                                                                    • Lusk, A. C., P. G. Furth, P. Morency, L. F. Miranda-Moreno, W. C. Willett, and J. T. Dennerlein. 2011. Risk of injury for bicycling on cycle tracks versus in the street. Injury Prevention 17:131–135.

                                                                      DOI: 10.1136/ip.2010.028696Save Citation »Export Citation »E-mail Citation »

                                                                      The authors used crash and exposure data to compare bicycling risk on several two-way cycle tracks in Montreal to bicycling risk along parallel routes without cycle tracks. The relative risk of injury from cycling on the cycle tracks was calculated to be 0.72 compared to bicycling on the reference streets.

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                                                                      • Reynolds, C. C. O., M. A. Harris, K. Teschke, P. A. Cripton, and M. Winters. 2009. The impact of transportation infrastructure on bicycling injuries and crashes: A review of the literature. Environmental Health 8.47.

                                                                        DOI: 10.1186/1476-069X-8-47Save Citation »Export Citation »E-mail Citation »

                                                                        The researchers reviewed twenty-three papers for findings on bicycling injuries, injury severity, and crashes. While the review was hindered by difficulties in controlling for exposure, the authors concluded that roadways with bicycle facilities posed a lower risk to cyclists than sidewalks, multi-use trails, or roadways without bicycle facilities.

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                                                                        • Teschke, K., M. A. Harris, C. C. O. Reynolds, et al. 2012. Route infrastructure and the risk of injuries to bicyclists: A case-crossover study. American Journal of Public Health 102.12: 2336–2343.

                                                                          DOI: 10.2105/AJPH.2012.300762Save Citation »Export Citation »E-mail Citation »

                                                                          The authors interviewed 690 injured cyclists’ from Vancouver and Toronto and mapped the routes along which they were injured. In order to perform a case control study, the researchers then randomly selected a control site along each route, and calculated the odds ratio of risk for each facility type.

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                                                                          Bicycling Risk in Shared Spaces

                                                                          Research related to shared space for bicyclists may take the form of studies on shoulders or wide lanes on the roadway, sidewalks, or the shared space of the intersection—all spaces that require bicyclists to navigate space with other users. This section represents a variety of findings, but it is clear that not all shared space is considered equal for bicycling comfort or safety. For example, in a study of sidewalk bicycling, Aultman-Hall and Adams 1998, the authors found that cyclists who ride on the sidewalk experience a higher rate of events than cyclists who don’t, although the sidewalk events are rarely reported. Wachtel and Lewiston 1994 analyzed intersection crashes between bicyclists and motor vehicles in Palo Alto and found that sidewalk riding was twice as risky as roadway riding. However, when this data was later reanalyzed (in Lusk, et al. 2011, cited under Bicycling Risk in Separated Spaces) with the non-intersection crashes, the increased risk of sidewalk riding disappeared. Harkey and Stewart 1997 and Hunter, et al. 1998, two wide curb lane versus bicycle lane studies, suggest that bicycle lanes confer more benefits than wide curb lanes for both bicyclists and motorists. However, Hunter, et al. 1998 stresses that wide curb lanes can still play a role in improving bicycling safety. Hunter, et al. 2011 evaluated the before and after period of a shared lane marking installation in Cambridge, Massachusetts. The authors found that the markings seem to improve safety, as both drivers and bicyclists drove further away from parked cars after the markings were painted, and there was less movement in general while driving and bicycling. Minikel 2012 provides a comparison of bicycle boulevards and parallel arterials in Berkeley, and the author found that the crash rates on the boulevards were two to eight times lower, which did not seem to be explained by self-selection or “safety in numbers.” With regard to intersection treatments, Dill, et al. 2012 examined bicycle boxes in Portland, Oregon, and found that pedestrians benefited from their installation, although bicyclists’ safety was less clearly positively affected. Surveys among bicyclists and drivers indicated that more people perceived safety benefits than not from the bike boxes. Birk, et al. 1999 examined blue painted lanes and accompanying signage through conflict areas in Portland, Oregon. The authors found mixed effects: although driver yielding increased, looking and signaling by bicyclists decreased. These findings suggest that engineering should be accompanied by additional efforts to improve bicyclist safety in shared spaces––particularly intersections.

                                                                          • Aultman-Hall, L., and M. F. Adams Jr. 1998. Sidewalk bicycling safety issues. Transportation Research Record 1636:71–76.

                                                                            DOI: 10.3141/1636-11Save Citation »Export Citation »E-mail Citation »

                                                                            The authors surveyed nearly twelve hundred residents of Toronto and Ottawa about their bicycling travel patterns and collision and fall history. The findings indicate that most collisions and falls on sidewalks are not reported, even when they resulted in major injuries, and that sidewalk cyclists experience higher rates of events than non-sidewalk cyclists.

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                                                                            • Birk, M., R. Burchfield, J. Flecker, et al. 1999. Portland’s blue bike lanes: Improved safety through enhanced visibility. Portland, OR: City of Portland Office of Transportation.

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                                                                              The researchers found that painted blue lanes and accompanying signage had mixed effects in conflict areas in Portland, Oregon. Motorists increased their yielding to the bicyclists, but both motorists and bicyclists decreased behaviors like signaling to merge and (for cyclists) looking over their shoulders.

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                                                                              • Dill, J., C. M. Monsere, and N. McNeil. 2012. Evaluation of bike boxes at signalized intersections. Accident Analysis and Prevention 44:126–134.

                                                                                DOI: 10.1016/j.aap.2010.10.030Save Citation »Export Citation »E-mail Citation »

                                                                                This study examined the behavior of bicyclists and motorists before and after bicycle boxes were installed to prevent right-turning conflict at intersections. The video suggests improvements for pedestrian safety, but mixed effects for bicycling safety––although surveys of user perceptions found support for them among both drivers and bicyclists.

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                                                                                • Harkey, D. L., and R. J. Stewart. 1997. Evaluation of shared-use facilities for bicycles and motor vehicles. Transportation Research Record 1578.1: 111–118.

                                                                                  DOI: 10.3141/1578-14Save Citation »Export Citation »E-mail Citation »

                                                                                  The authors evaluated bicyclist and motorist interactions on roadways with wide curb lanes, bicycle lanes, and paved shoulders. They found that motorists tended to give slightly more space when passing in the wide curb lane, but that bicyclists rode closer to the right (resulting in potentially less room for error) in that situation.

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                                                                                  • Hunter, W. W., R. Srinivasan, L. Thomas, C. A. Martell, and C. B. Seiderman. 2011. Evaluation of shared lane markings in Cambridge, Massachusetts. Transportation Research Record 2247:72–80.

                                                                                    DOI: 10.3141/2247-09Save Citation »Export Citation »E-mail Citation »

                                                                                    This study evaluated cyclists’ and motorists’ behavior before and after shared lane markings (sharrows) were installed on a street in Cambridge, Massachusetts. The researchers found that both cars and bicyclists tended to drive further from the curb post-installation, suggesting that the sharrows positively affected roadway safety.

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                                                                                    • Hunter, W. W., R. J. Stewart, J. C. Stutts, H. H. Huang, and W. E. Pein. 1998. Bicycle lanes versus wide curb lanes: Operational and safety findings and countermeasure recommendations. McLean, VA: Federal Highway Administration.

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                                                                                      Authors analyzed bicyclist and motorist actions on roadways with wide curb lanes and bicycle lanes in several locations. The authors found that wrong-way riding, sidewalk riding, and motorist encroachment into oncoming traffic were less prevalent at the bike lane locations. However, they conclude that both facilities have a role in improving bicycling conditions.

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                                                                                      • Minikel, E. 2012. Cyclist safety on bicycle boulevards and parallel arterial routes in Berkeley, California. Accident Analysis and Prevention 45:241–247.

                                                                                        DOI: 10.1016/j.aap.2011.07.009Save Citation »Export Citation »E-mail Citation »

                                                                                        The author used crash reports and count data to compare the crash rates and injury severity of bicycle boulevards to parallel arterial routes in Berkeley, California. Although there was no difference in injury severity, the data suggest that crash rates on bicycle boulevards are two to eight times lower than rates on parallel arterials.

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                                                                                        • Wachtel, A., and D. Lewiston. 1994. Risk factors for bicycle-motor vehicle collisions at intersections. ITE Journal (September): 30–35.

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                                                                                          The authors studied bicycle crash data from intersection and junction crashes in Palo Alto and found that the risk of sidewalk riding was nearly double that of roadway riding. In particular, adult bicyclists riding against traffic on the sidewalk had the highest risk of any subgroup tested.

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                                                                                          Route Choice and Environment

                                                                                          Research related to route choice often includes a bicycle safety component simply because perceptions of risk tend to play an important part in one’s choice of where to ride. Many of these studies have been “stated preference,” wherein a subject is given a choice between two alternatives and chooses the best alternative multiple times before the researchers can determine the values of various route features. These studies provide the opportunity to test roadway designs that may not currently exist in one’s city, but they are limited in that they are only stated preference, and they may never come to fruition. On the other hand, revealed preference studies require a lot more effort to conduct. If using GPS or another monitoring device, the researchers must monitor the data to be sure it is being captured correctly, and there is often extensive pretesting. Revealed preference without GPS, such as through having research participants retrace routes, is subject to recall bias. The preference studies in this section, while making trade-offs between these methods, are instructive in that they reveal the role of roadway design features and traffic in bicyclists’ route choices. Tilahun, et al. 2007 used computer-generated alternatives to establish a stated preference model for elements of route choice. Sener, et al. 2009 used a stated preference framework to develop a route choice model based on a survey of over sixteen hundred Texas bicyclists. Winters, et al. 2011 created a route preference model based on the difference between actual routes and the alternative shortest-path route. Landis, et al. 1997 recruited volunteers to ride a segmented route that the volunteers then graded and the researchers analyzed to determine a revealed preference model for bicycling. Broach, et al. 2012 is one of the latest of these studies, using GPS to monitor the routes of 164 cyclists over several days. They were then able to create a model based on revealed, real-time preferences that could account for trade-offs in topography, traffic volumes, and street network characteristics. While the methods differ, these studies all found that cyclists seem to put a premium on separation from traffic, although the separation does not necessarily have to be in the form of a bicycle lane or path.

                                                                                          • Broach, J., J. Dill, and J. Gliebe. 2012. Where do cyclists ride? A route choice model developed with revealed preference GPS data. Transportation Research Part A 46:1730–1740.

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                                                                                            This study used GPS devices to monitor 164 cyclists as they bicycled throughout Portland, Oregon, for several days. The researchers used the data to develop a route choice model based on revealed preferences as well as street network, topography, and traffic volume data.

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                                                                                            • Landis, B. W., V. R. Vattikuti, and M. T. Brannick. 1997. Real-time human perceptions: Toward a bicycle level of service. Transportation Research Record 1578:119–126.

                                                                                              DOI: 10.3141/1578-15Save Citation »Export Citation »E-mail Citation »

                                                                                              This research employed a group of volunteers to bicycle and then grade each segment of a predetermined route in Orlando, Florida. The authors used this information to model real-time preferences for bicycling conditions, although the study was limited by to certain segment features by its own design.

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                                                                                              • Sener, I. N., N. Eluru, and C. R. Bhat. 2009. An analysis of bicycle route choice preferences in Texas, US. Transportation 36:511–539.

                                                                                                DOI: 10.1007/s11116-009-9201-4Save Citation »Export Citation »E-mail Citation »

                                                                                                This stated preference study was conducted via an online survey of 1,621 Texas bicyclists. Separate models for commute and noncommute trips were tested with variables for bicyclist characteristics; on-street parking variables; bicycle facility characteristics; and physical, functional, and operational characteristics of the roadway.

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                                                                                                • Tilahun, N. Y., D. M. Levinson, and K. J. Krizek. 2007. Trails, lanes, or traffic: Valuing bicycle facilities with an adaptive stated preference survey. Transportation Research Part A 41:287–301.

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                                                                                                  The authors presented route alternatives to 167 participants via a computer program. As the survey progressed, the route choices adapted until a trade-off between facility type and time could reliably be established. This data was then used to build mixed logit and linear utility models for route preferences.

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                                                                                                  • Winters, M., K. Teschke, M. Grant, E. M. Setton, and M. Brauer. 2011. How far out of the way will we travel? Built environment influences on route selection for bicycle and car travel. Transportation Research Record 2190:1–10.

                                                                                                    DOI: 10.3141/2190-01Save Citation »Export Citation »E-mail Citation »

                                                                                                    This study compared the shortest-route alternative to fifty utilitarian bicycle trips and sixty-seven car trips in Vancouver, British Columbia. The researchers used GIS and statistical analysis to analyze the built environments of each route and determine which features were associated with route choice or avoidance.

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                                                                                                    Subjectively Measured Risk

                                                                                                    Studies about the subjective risk of bicycling have tended to take the form of surveys that query respondents about beliefs about and barriers to bicycling (particularly various risks), and preferences for roadway design. Dill and Voros 2007 found that over half of the people in a Portland survey who want to bicycle more were worried about too much traffic, and over one-third requested more bicycle lanes and trails. Winters, et al. 2011 found that three of the top five deterrents to increased bicycling were related to concerns about traffic safety, even for experienced bicyclists. Sener, et al. 2009, a survey of bicyclists in Austin, Texas, found that a large majority of respondents perceived bicycling with traffic to be dangerous, with the perceived risk being negatively associated with bicycling frequency. Washington, et al. 2012, a survey of Queensland bicyclists, also found that perceived risk was negatively associated with bicycling frequency, as well as the proportion of time spent riding on a bicycle path. It is no wonder that bicyclists feel at risk: as the Objectively Measured Risk section shows, bicycling is relatively much more dangerous than driving, walking, or taking transit. Bicycling risk is influenced not only by roadway design and speed limits that often encourage faster driving, but also by driver attitudes. Basford, et al. 2003 found that drivers who bicycle are much more sympathetic—and tend to give bicyclists more room on the road—than drivers who don’t bicycle. Granville, et al. 2001 also found that drivers who bicycle are more sympathetic toward cyclists, but that the overwhelming sense of cyclists was that they did not deserve roadway priority.

                                                                                                    • Basford, L., S. Reid, T. Lester, J. Thomson, and A. Tolmie. 2003. Drivers’ perceptions of cyclists. TLR Report TLR549. Crowthorne, UK: Transport Research Laboratory.

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                                                                                                      The authors conducted focus groups and interviews with seventy-eight drivers in the United Kingdom to understand their attitudes and behavior toward cyclists. While the researchers found a high level of negativity toward cyclists, particularly among professional drivers, there did not seem to be aggressive behavior following from it.

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                                                                                                      • Dill, J., and K. Voros. 2007. Factors affecting bicycling demand: Initial survey findings from the Portland, Oregon, region. Transportation Research Record 2031:9–17.

                                                                                                        DOI: 10.3141/2031-02Save Citation »Export Citation »E-mail Citation »

                                                                                                        The authors conducted a random-digit-dial survey of Portland residents and found that 65 percent of respondents would like to bicycle more. Of those, 57 percent cited “too much traffic” as a barrier, and 37 percent wanted more bike lanes and trails.

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                                                                                                        • Granville, S., F. Rait, M. Barber, and A. Laird. 2001. Sharing road space: Drivers and cyclists as equal road users. Edinburgh: Scottish Executive Central Research Unit.

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                                                                                                          This study explored attitudes toward bicyclists, drivers, and motorcyclists through in-depth interviews with road users in Edinburgh and Aberdeen, Scotland. Bicyclists were viewed as not deserving roadway priority because of perceptions of their behavior, failure to pay road tax, and slow speed. Drivers who bicycled were more sympathetic than noncycling drivers.

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                                                                                                          • Sener, I. N., N. Eluru, and C. R. Bhat. 2009. Who are bicyclists? Why and how much are they bicycling? Transportation Research Record 2134:63–72.

                                                                                                            DOI: 10.3141/2134-08Save Citation »Export Citation »E-mail Citation »

                                                                                                            The authors surveyed bicyclists in Austin, Texas, and found that bicycling frequency was affected by perceptions of danger, bicycle facility quality, and benefits from cycling, as well as a flexible work schedule, bicycling amenities at work, weather, gender, and age.

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                                                                                                            • Washington, S., N. L. Haworth, and A. J. Schramm. 2012. On the relationships between self-reported bicycling injuries and perceived risk among cyclists in Queensland, Australia. Paper presented at the 91st Annual Meeting of the Transportation Research Board, Washington, DC, 22–26 January 2012.

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                                                                                                              The researchers examined self-reported bicycling risk and injury rates from crash and noncrash injuries (e.g., muscle sprains) as a function of exposure, rider visibility, environment, risk aversion, and experience levels. They found no significant association between injury rates and perceived cycling risk, although they did not separate motor vehicle and solo crashes.

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                                                                                                              • Winters, M., G. Davidson, D. Kao, and K. Teschke. 2011. Motivators and deterrents of bicycling: Comparing influences on decisions to ride. Transportation 38.1: 153–168.

                                                                                                                DOI: 10.1007/s11116-010-9284-ySave Citation »Export Citation »E-mail Citation »

                                                                                                                This study examined dozens of motivators and barriers to bicycling among 1,402 current and potential cyclists in the Vancouver area. The researchers found the top barriers to be inclement weather, traffic volume, traffic speed, debris, and unskilled drivers. Top motivators included separation from traffic, scenery, flat topography, and short distance.

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                                                                                                                Unreported Risk: Near Misses and Non-traffic Risk

                                                                                                                The majority of cycling safety research understandably focuses on topics for which there is data to analyze. One aspect of cycling safety, the “near miss,” is therefore routinely understudied due to a lack of data. Only a few studies exist that examine this potentially significant aspect of bicycling safety. Much more research is needed to understand how prevalent near misses of various types are, how they affect perceptions of traffic risk for bicyclists of varying experience levels, and what efforts can be established to lessen the prevalence and risk imparted from them. The research in this section represents this burgeoning area of research. Joshi, et al. 2001 is a diary study of roadway users in the United Kingdom that found that bicyclists experience not only experience an incident (“near miss” or collision) frequently, they also experience many times more incidents than drivers. Sanders 2013 examined “near misses” through a survey of drivers and bicyclists in the Bay Area and found that “near miss” experiences significantly affected perceptions of traffic risk for bicyclists. Poulos, et al. 2011 reports on an ongoing large study of “near misses” and injuries for Australian cyclists. There are also other types of risks cyclists may routinely face, although again there is little data on these risks due to a lack of formal reporting mechanism. The National Survey of Bicyclist and Pedestrian Attitudes and Behavior provides a snapshot view of the non-traffic types of risks cyclists may face in the United States.

                                                                                                                • Joshi, M. S., V. Senior, and G. P. Smith. 2001. A diary study of the risk perceptions of road users. Health, Risk & Society 3.3: 261–279.

                                                                                                                  DOI: 10.1080/13698570120079877Save Citation »Export Citation »E-mail Citation »

                                                                                                                  The authors analyzed trip diaries from 291 road users in the United Kingdom, and found that cyclists experienced an average of one incident (“near miss” or collision) every 5.6 miles, or 0.7 incidents per day. This equated to a perceived risk 7.5 times greater than motorized road users.

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                                                                                                                  • Poulos, R. G., J. Hatfield, C. Rissel, R. Grzebieta, and A. S. McIntosh. 2011. Exposure-based cycling crash, near miss and injury rates: The Safer Cycling Prospective Cohort Study protocol. Injury Prevention 2012.18: 1–4.

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                                                                                                                    This longitudinal study is underway, but it has the potential to be the most thorough examination of near misses and their relation to injury rates to date.

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                                                                                                                    • Royal, D., and D. Miller-Steiger. 2008. National Survey of Bicyclist and Pedestrian Attitudes and Behavior. Vol. 2, Findings report. DOT HS 810 972. Washington, DC: National Highway Traffic Safety Administration.

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                                                                                                                      The National Survey was conducted by telephone with over 9,600 US residents. The data revealed that, while respondents felt threatened by motor vehicles more than anything else, there were also cyclists who felt threatened by stray dogs and other animals, uneven riding surfaces, and the potential for crime.

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                                                                                                                      • Sanders, R. 2013. Dissecting perceived traffic risk as a barrier to adult bicycling. Paper presented at the 92nd Annual Meeting of the Transportation Research Board, Washington, DC, 13–17 January 2013.

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                                                                                                                        This research investigated perceived bicycling risks among a population of 463 drivers and bicyclists in the Bay Area. The author found that several perceived risks for frequent cyclists were significantly related to “near miss” experiences. In addition, “near misses” are much more prevalent than official crash statistics for related collisions would suggest.

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                                                                                                                        Bicycle Helmets

                                                                                                                        In general, the literature strongly advocates the role of helmets in protecting bicycle riders from trauma to the head. However, there is some disagreement over the holistic benefit of helmets, with some researchers claiming the paramount importance of protecting cyclists from acute head injury, while others believe that helmet use—particularly when mandated by law—discourages cycling and therefore makes it more dangerous overall. The studies below present several issues related to helmet use and the safety provided by helmets. Attewell, et al. 2001 summarizes peer-reviewed studies examining the safety benefits of helmets. It also discusses some confounding factors, such as selection bias, alcohol use, and risk-taking behavior, that likely affect cyclist safety. Elvik 2011 presents a new analysis of the meta-analysis of Attewell, et al. 2001. Walker 2007 also discusses issues related to risk compensation. Lee, et al. 2005 and Robinson 2006 explore, from different perspectives, the effect of bicycle helmet laws, a policy that several states have implemented (mostly for minor riders), and that has been controversial in the United States. Spaite, et al. 1991 reports on an epidemiological study that examined injury severity. Thompson, et al. 2009 summarizes research in a Cochrane Review about the effectiveness of bicycle helmets in preventing head and facial injury. Hagel, et al. 2010 presents an observational study on bicycle helmet misuse, before and after helmet legislation. In Karkhaneh, et al. 2006, a review of eleven studies exploring the effects of bicycle helmet legislation is presented.

                                                                                                                        • Attewell, R. G., K. Glase, and M. McFadden. 2001. Bicycle helmet efficacy: A meta-analysis. Accident Analysis and Prevention 33:345–352.

                                                                                                                          DOI: 10.1016/S0001-4575(00)00048-8Save Citation »Export Citation »E-mail Citation »

                                                                                                                          The authors examined studies of the protection helmets offer in preventing traffic-related injury, concluding helmets play a significant and preventive role in reducing bicyclist injury. One confounding factor can be risk-taking behavior––helmet users may be more careful cyclists and may be less likely than others to get injured.

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                                                                                                                          • Elvik, R. 2011. Publication bias and time-trend bias in meta-analysis of bicycle helmet efficacy: A re-analysis of Attewell, Glase and McFadden, 2001. Accident Analysis and Prevention 43:1245–1251.

                                                                                                                            DOI: 10.1016/j.aap.2011.01.007Save Citation »Export Citation »E-mail Citation »

                                                                                                                            A re-analysis of this previous study still showed safety benefits from helmet use, but at a smaller level. The re-analysis included additional studies and examined potential issues related to publication bias, such as studies not being published or analyzed via meta-analysis when they contradict previously published studies or fail to find statistically significant results, and time-trend bias, such as the diminishing safety effects of bicycle helmets over time.

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                                                                                                                            • Hagel, B. E., R. S. Lee, Karkhaneh, D. Voaklander, and B. H. M. Rowe. 2010. Factors associated with incorrect bicycle helmet use. Injury Prevention 16:178–184.

                                                                                                                              DOI: 10.1136/ip.2009.023994Save Citation »Export Citation »E-mail Citation »

                                                                                                                              This paper reports on observational studies conducted of bicycle helmet misuse among children and adults at two points in time––before and after helmet legislation. Children were more likely to wear helmets incorrectly. Incorrect use declined for all ages after helmet legislation was passed.

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                                                                                                                              • Karkhaneh, M., J.-C. Kalenga, B. E. Hagel, and B. H. Rowe. 2006. Effectiveness of bicycle helmet legislation to increase helmet use: A systematic review. Injury Prevention 12:76–82.

                                                                                                                                DOI: 10.1136/ip.2005.010942Save Citation »Export Citation »E-mail Citation »

                                                                                                                                This review looks at the literature regarding the effectiveness of legislation designed to increase bicycle helmet use among all ages of cyclists. It looks at different types of studies, all community based. Legislation generally increased use, especially among children. Where the baseline level was the lowest, the increase was the largest. The review also cites studies that looked at the effect that legislation might have on cycling rates.

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                                                                                                                                • Lee, B. H., J. L. Schofer, and F. S. Koppelman. 2005. Bicycle safety helmet legislation and bicycle-related non-fatal injuries in California. Accident Analysis and Prevention 37:93–102.

                                                                                                                                  DOI: 10.1016/j.aap.2004.07.001Save Citation »Export Citation »E-mail Citation »

                                                                                                                                  Comparing youth aged seventeen and under subject to California’s helmet law, with adults not subject to it, the authors found a significant reduction in traumatic brain injury among helmeted youth. While the prevalence of use is not known, injury data from before and after the law allows for this conclusion.

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                                                                                                                                  • Robinson, D. L. 2006. No clear evidence from countries that have enforced the wearing of helmets. British Medical Journal 332:722–725.

                                                                                                                                    DOI: 10.1136/bmj.332.7543.722-aSave Citation »Export Citation »E-mail Citation »

                                                                                                                                    This paper questions the efficacy of helmet laws, noting that helmeted users might be more risk-averse, and raising questions about case-control studies and incorrect helmet use.

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                                                                                                                                    • Spaite D. W., M. Murphy, E. A. Criss, T. D. Valenzuela, and H. W. Meislin. 1991. A prospective analysis of injury severity among helmeted and nonhelmeted bicyclists involved in collisions with motor vehicles. Journal of Trauma 11:1510–1516.

                                                                                                                                      DOI: 10.1097/00005373-199111000-00008Save Citation »Export Citation »E-mail Citation »

                                                                                                                                      Patients admitted for serious trauma in the emergency room were analyzed for helmet use, among other characteristics. Nonhelmeted cyclists were more likely to incur serious injuries and to die from those injuries.

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                                                                                                                                      • Thompson, D. C., F. Rivara, and R. Thompson. 2009. Helmets for preventing head and facial injuries in bicyclists. Cochrane Database of Systematic Reviews 4.CD001855.

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                                                                                                                                        This review highlighted case control studies of bicyclists injured in bicycle crashes (case) and those treated for non-bicycle crash injuries and non-head injuries (control). The authors concluded that helmet use is protective, and that educational programming and legislation on helmet use and injury prevention has had a positive impact. Feedback questioning sampling and methodology are included, as well as authors’ responses to these comments.

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                                                                                                                                        • Walker, I. 2007. Drivers overtaking bicyclists: Objective data on the effects of riding position, helmet use, vehicle type and apparent gender. Accident Analysis and Prevention 39:417–425.

                                                                                                                                          DOI: 10.1016/j.aap.2006.08.010Save Citation »Export Citation »E-mail Citation »

                                                                                                                                          Drivers overtaking bicycles result in serious collisions. Using bicycles instrumented with sensors and riders with video cameras to monitor proximity of overtaking, the author found that drivers were more likely to give helmeted cyclists less passing distance, perhaps due to perception of cyclists being less at risk and/or more experienced than others.

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                                                                                                                                          Conspicuity and Bicycling

                                                                                                                                          In recent years, interest has been generated in the subject of cyclist visibility and the use of conspicuity aids. The literature strongly supports the protective benefit of conspicuity aids, although studies have found dramatic differences in the effectiveness of a variety of aids. Kwan and Mapstone 2006 presents the results of a Cochrane Review of forty-two research studies on conspicuity aids for pedestrians and cyclists. Blomberg, et al. 1986 is a specific example of broadly covered research in the related Cochrane Review; in this paper, the authors compare various visibility aids for cyclists and pedestrians at night. Wood, et al. 2012 offers a more recent examination of the subject in a controlled environment. While controlled trials are helpful to evaluate the effectiveness of aids in enhancing detection and recognition, they do not elucidate how conspicuity aids affect actual injury and collision rates. Thornley, et al. 2008 contributes to that gap, describing the results of a population study to understand the prevalence of conspicuity aids in crashes.

                                                                                                                                          • Blomberg, R. D., A. Hale, and D. F. Preusser. 1986. Experimental evaluation of alternative conspicuity-enhancement techniques for pedestrians and cyclists. Journal of Safety Research 17:1–12.

                                                                                                                                            DOI: 10.1016/0022-4375(86)90002-2Save Citation »Export Citation »E-mail Citation »

                                                                                                                                            Authors examined conspicuity enhancements for cyclists and pedestrians using thirty-six test drivers on a closed driving course. Both detection and recognition of the device were tested. The active lights (e.g., flashlights) were detected significantly sooner than the passive ones (e.g., reflective strips), suggesting their superiority in enhancing visibility.

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                                                                                                                                            • Kwan, I., and J. Mapstone. 2006. Interventions for increasing pedestrian and cyclist visibility for the prevention of death and injuries. Cochrane Database of Systematic Reviews 4.CD003438.

                                                                                                                                              DOI: 10.1002/14651858.CD003438.pub2Save Citation »Export Citation »E-mail Citation »

                                                                                                                                              This systematic review of randomized controlled trials and before-and-after trials of visibility aids for pedestrians and cyclists found that (1) fluorescent materials enhanced daytime visibility and detection; (2) lamps, flashing lights, and retroreflective materials enhance both aspects at night; and (3) “biomotion” markings (reflecting the human form) improved recognition.

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                                                                                                                                              • Thornley, S. J., A. Woodward, J. D. Langley, S. N. Ameratunga, and A. Rodgers. 2008. Conspicuity and bicycle crashes: Preliminary findings of the Taupo Bicycle Study. Injury Prevention 14:11–18.

                                                                                                                                                DOI: 10.1136/ip.2007.016675Save Citation »Export Citation »E-mail Citation »

                                                                                                                                                Authors examined the crash experiences of nearly 2,500 cyclists to understand how the use of fluorescent colors contributed to crash rates. After controlling for confounding factors, the authors found that riders who always wore fluorescent colors were substantially less likely to experience a debilitating bicycle crash injury.

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                                                                                                                                                • Wood, J. M., R. A. Tyrrell, R. Marszalek, P. Lacherez, T. Carberry, and B. Sun Chu. 2012. Using reflective clothing to enhance the conspicuity of bicyclists at night. Accident Analysis and Prevention 45:726–730.

                                                                                                                                                  DOI: 10.1016/j.aap.2011.09.038Save Citation »Export Citation »E-mail Citation »

                                                                                                                                                  This study employed groups of drivers on a closed course to evaluate detection and recognition of cyclists with various configurations of reflective clothing and lights. Bicyclists were detected and recognized significantly sooner with reflective knee and ankle strips, in contrast to vests. Unexpectedly, lights were associated with decreased response distance.

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                                                                                                                                                  Efforts to Improve Bicycling Safety

                                                                                                                                                  Improving bicycle safety requires multidisciplinary approaches. Professionals have come to describe the “Five Es” of such an approach, comprising engineering, enforcement, education, encouragement, and evaluation. The inherent idea is that no one area can alone be expected to remedy traffic risk. For example, improving the bicycle infrastructure is important, but enforcing slower speeds and educating cyclists is part of the equation. The articles below provide a sample of studies and reports that present the various “Es” for improving bicyclist safety. International Technology Scanning Program 2010 is written by professionals from the United States who have studied policies in five European countries that have innovative and multidisciplinary approaches to improving the cycling environment. Policy development is an important part of their approaches, and these policies, including Complete Streets, are outlined. Examples of multiple “Es” of safety are outlined in Osland, et al. 2012. By presenting case studies, the authors provide concrete examples of how cities in the United States have implemented broad-based improvements. The Transportation Research Board’s National Cooperative Highway Safety Research Program studies road safety design around the United States and develops evidence-based strategies for implementing countermeasures. Raborn, et al. 2008, the program’s bicycle safety report, outlines evidence-based and promising strategies and types of bicycle safety improvements. The need for behavioral approaches, including training and education, is highlighted in the European Commission’s Report on “vulnerable road users” (Transport Research Laboratory 2001). On the streets, intersections can be particularly dangerous for nonmotorized road users. Weigand 2008 provides a review of treatments that can be implemented to make it easier and safer to cycle. In terms of educational approaches, Van Houten, et al. 2007 discusses the evaluation of a safety education and encouragement program focused on increased and sustained helmet use at three middle schools in the United States. As discussed in the Population Differences in Cycling Risk section, special groups may bear a disproportionate burden of traffic risk. Knoblauch and Seifert 2004 focuses on approaches to promoting bicycle safety among Hispanic populations in the United States, a large and growing population. The authors conducted focus groups in a range of Hispanic communities and developed recommendations for planning and programming that can effectively reach diverse, and bilingual (English- and Spanish-speaking), communities. Exploring another special at-risk population, youth, Feenstra, et al. 2010 evaluates effective approaches for working with high-risk youth.

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