摘要：Objectives. We studied state-adopted bicycle guidelines to determine whether cycle tracks (physically separated, bicycle-exclusive paths adjacent to sidewalks) were recommended, whether they were built, and their crash rate. Methods. We analyzed and compared US bicycle facility guidelines published between 1972 and 1999. We identified 19 cycle tracks in the United States and collected extensive data on cycle track design, usage, and crash history from local communities. We used bicycle counts and crash data to estimate crash rates. Results. A bicycle facility guideline written in 1972 endorsed cycle tracks but American Association of State Highway and Transportation Officials (AASHTO) guidelines (1974–1999) discouraged or did not include cycle tracks and did not cite research about crash rates on cycle tracks. For the 19 US cycle tracks we examined, the overall crash rate was 2.3 (95% confidence interval = 1.7, 3.0) per 1 million bicycle kilometers. Conclusions. AASHTO bicycle guidelines are not explicitly based on rigorous or up-to-date research. Our results show that the risk of bicycle–vehicle crashes is lower on US cycle tracks than published crashes rates on roadways. This study and previous investigations support building cycle tracks. Bicycle riding has many positive benefits related to health 1–20 as well as to transportation 21,22 and the environment. 23,24 Because the metabolic-equivalent intensity levels for bicycling are higher than those for walking, 25 bicycling can be even more beneficial than walking with respect to weight control, 26 all-cause mortality, 27,28 and heart function 29 among adults, and with respect to physical fitness 30 and cardiovascular health 31 among children. In the United States, 68% of the population is overweight or obese, 32 and 34% of children and adolescents are overweight or at risk for being overweight. 33 Although bicycling is beneficial, US census data show that only 0.5% of US residents aged 16 years or older use a bicycle as a means of transportation to and from work, and only 24% of these bicyclists are female. 34 This low rate of cycling may be attributable in part to the lack of proper bike facilities. In the Netherlands, where there are 29 000 km of cycle tracks, 35 27% of trips are made by bicycle and, of total bicycle trips, 55% are made by female bicyclists. 36 In Montreal, Canada, where cycle track networks were initiated 20 years ago and there are now 63 kilometers of on-road cycle tracks along with 173 kilometers of park and riverside cycle tracks, bicycle volumes have increased tremendously. 37 In both the Netherlands 38 and Montreal, 39 detailed guidelines have long existed that support the implementation of cycle tracks. Recent research articles, reviews, and reports on bicycle facilities have noted the benefits of cycle tracks. 40–46 However, other recent articles on bicycle facilities have described only the need for separation of bicyclists from cars 47 or have not included analyses or discussions of cycle tracks. 48–52 In the United States, the guidelines of the American Association of State Highway and Transportation Officials (AASHTO) favor bicycling on roadways, even though most women, children, and seniors prefer separation from vehicles. 36,53–60 Discouraged in these guidelines is the building of bicycle facilities resembling cycle tracks, that is, physically separated and bicycle-exclusive paths adjacent to sidewalks. Past research articles on cycle track–related facilities, such as sidewalk bikeways and road-parallel shared-use paths, 61–63 have been used to discourage creation of cycle tracks in the United States. No studies have offered precise estimates of the existence and safety of US cycle tracks. The US Department of Transportation policy statement recommends that the design of bicycle and pedestrian facilities follow the best currently available standards and design guidelines, such as AASHTO’s Guide for the Development of Bicycle Facilities and A Policy on Geometric Design of Highways and Streets and the Institute of Transportation Engineers’ Design and Safety of Pedestrian Facilities . 64 Thus, AASHTO guidelines, commonly available and used by state departments of transportation, have primarily directed the design of US bicycle facilities. The new National Association of City Transportation Officials bike guide 65 includes cycle tracks. However, without inclusion of cycle tracks in the commonly adopted AASHTO guide, without US-based cycle track research, and without public health and transportation policies in support of cycle tracks, it will continue to be difficult to create cycle track networks. Furthermore, in the public participation process often only a few individuals attend the evening hearings, and they include adjacent residents who are opponents of changes to the street and bicyclists who prefer the road as opposed to large numbers of potential bicyclists, including women, children, and seniors. The design is, therefore, often biased toward leaving the road virtually unchanged. As a result of these and many other historical reasons, the default bicycle facility in the United States remains a bike lane painted on a road, 66 in which many bicyclists do not feel comfortable 67 or safe. 68 We analyzed past and current state-adopted bicycle guidelines to assess the justifications for and level of rigor applied to recommendations for the use of bicycle facilities in the United States. Also, we determined, notwithstanding the AASHTO guidelines, whether cycle tracks had been built in the United States and their characteristics. Finally, we examined whether the rate of vehicle–bicycle crashes on US cycle tracks was lower than published rates for bicyclists on roadways.
