摘要：Objectives. We compared cycling injury risks of 14 route types and other route infrastructure features. Methods. We recruited 690 city residents injured while cycling in Toronto or Vancouver, Canada. A case-crossover design compared route infrastructure at each injury site to that of a randomly selected control site from the same trip. Results. Of 14 route types, cycle tracks had the lowest risk (adjusted odds ratio [OR] = 0.11; 95% confidence interval [CI] = 0.02, 0.54), about one ninth the risk of the reference: major streets with parked cars and no bike infrastructure. Risks on major streets were lower without parked cars (adjusted OR = 0.63; 95% CI = 0.41, 0.96) and with bike lanes (adjusted OR = 0.54; 95% CI = 0.29, 1.01). Local streets also had lower risks (adjusted OR = 0.51; 95% CI = 0.31, 0.84). Other infrastructure characteristics were associated with increased risks: streetcar or train tracks (adjusted OR = 3.0; 95% CI = 1.8, 5.1), downhill grades (adjusted OR = 2.3; 95% CI = 1.7, 3.1), and construction (adjusted OR = 1.9; 95% CI = 1.3, 2.9). Conclusions. The lower risks on quiet streets and with bike-specific infrastructure along busy streets support the route-design approach used in many northern European countries. Transportation infrastructure with lower bicycling injury risks merits public health support to reduce injuries and promote cycling. Bicycling is an active mode of transportation with a range of individual and public health benefits. 1–5 However, bicycling is underused for transportation in Australia, Canada, Ireland, the United States, and the United Kingdom, constituting an estimated 1% to 3% of trips, compared with 10% to 27% of trips in Denmark, Germany, Finland, the Netherlands, and Sweden. 6–8 The reasons for low bicycle share of trips are multifaceted, but safety is one of the most frequently cited deterrents. 9–11 These concerns are well founded: bicycling injury rates are higher in countries where cycling for transportation is less common. 8,12,13 To reduce bicycling injuries, the first step is to understand the determinants of risk. Studies in many English-speaking countries have focused on head injury reductions afforded by helmets. 14–17 However, helmet use cannot explain the risk difference because helmets are rarely used in the European countries with lower injury rates. 8,18,19 Typical route infrastructure (physical transportation structures and facilities) in countries with low bicycle share of trips differs from that in countries with high trip shares. In Germany, Denmark, and the Netherlands, bicycle-specific infrastructure is frequently available, 20 so this is a promising avenue for investigating injury risks. In a review of route infrastructure and injury risk, 21 we found some evidence that bicycle-specific infrastructure was associated with reduced risk. However, the studies reviewed had problems that have compromised confidence in the results: grouping of route categories that may have different risks, unclear definitions of route infrastructure, and difficulty controlling for characteristics of cyclists and for exposure to various route types. Debates continue about the contribution of route design to safety and about the safety of various route types. 12,13,20,21 Here we present a study designed to overcome these limitations. 22 We examined injury risk of 14 route types using a case-crossover design in which injured participants served as their own controls. The design compared route characteristics at the location where the injury event occurred to those at a randomly selected point on the same trip route where no injury occurred. By randomly selecting the control site in this way, the probability that a specific infrastructure type would be chosen was proportional to its relative length on the trip (e.g., on a 4-km trip, there would be a 25% chance of selecting a control site on a 1-km section that was on a bike path). Because comparisons were within-trip, personal characteristics such as age, gender, and propensity for risk-taking behavior were matched, as were trip conditions such as bicycle type, clothing visibility, helmet use, weather, and time of day. This allowed the comparisons to focus on between-site infrastructure differences.
