Modelled health impacts of the London public bike scheme

摘要

Background & Aims Bicycle sharing systems are being implemented in many cities worldwide, but have received little robust evaluation. We modelled the impacts of the London cycle hire scheme (LCH) upon the health of its users. Methods Data sources included total-population operational registration and usage data for LCH; surveys of LCH users; and London data on travel, physical activity, road traffic collisions and PM2.5 air pollution. We quantified health impacts in terms of disability-adjusted life years (DALYs), using a stochastic transport health impact simulation model (ITHIM). Route-specific PM 2.5 exposure was estimated based on a route choice model and differential ventilation rates. We investigated the contribution of parametric uncertainty to the final result and used deterministic sensitivity analysis to investigate generalisabilty. Results Over one year, 578,607 users made 7.4 million LCH trips (71% by men). These would mostly otherwise have been walked or by public transport. The age structure of the LCH population was much younger than the background population. To date there have been no fatalities on hire bikes and a trend towards fewer injuries than expected for London cycling. Using these observed injury rates, physical activity benefits substantially outweighed risks among males and among females. When we modelled injury rates as being equal to rates for all cycling in central London, however, these benefits reduced, with no significant benefit amongst women. This sex difference reflected comparatively high fatality rates for female cyclists. Results by age show the trade-off between benefits and harms improves rapidly with age for both men and women. Health changes from changes in PM 2.5 exposure were small. Conclusion LCH appears to have had positive health impacts so far. For cycling in general, however, there appears to be an excess risk of fatality for females. For middle-aged and older cyclists benefits are far clearer than for young adults. Measures should be taken that both reduce injury risk and make cycling more attractive.