Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, UK.
Inj Prev. 2013 Jun;19(3):211-3. doi: 10.1136/injuryprev-2012-040347. Epub 2012 Aug 30.
Evidence suggests that 20 mph zones are an effective intervention to reduce casualties from road traffic crashes in urban areas. This analysis compares the costs of construction of the 20 mph zone intervention in high and low casualty areas in London to the value of casualties avoided over 5 and 10 year time horizons. Probabilistic sensitivity analyses were conducted to quantify uncertainty in the results associated with model parameters. Results indicate a net present value (NPV) of £18 947 (90% credible limits -£75 252 to £82 021 2005 prices) after 5 years and £67 306 (£-29 157 to £137 890) after 10 years when 20 mph zones are implemented in areas with one or more casualty per kilometre of road. Simulations from our model suggest that the 'threshold of casualties' where NPVs become positive using a 10 year time horizon is 0.7 casualties per kilometre.
有证据表明，20 英里/小时限速区是减少城市地区道路交通碰撞伤亡的有效干预措施。本分析比较了在伦敦高伤亡区和低伤亡区实施 20 英里/小时限速区干预措施的建设成本与避免 5 年和 10 年时间范围内伤亡的价值。进行了概率敏感性分析，以量化与模型参数相关的结果不确定性。结果表明，在实施 20 英里/小时限速区后 5 年的净现值（NPV）为 18947 英镑（90%置信区间为-29157 至 137890 英镑，2005 年价格），10 年后为 67306 英镑（-29157 至 137890 英镑）。当在每公里道路有一个或多个伤亡的区域实施 20 英里/小时限速区时。我们的模型模拟表明，使用 10 年时间范围时，NPV 变为正值的“伤亡阈值”为每公里 0.7 人伤亡。
