This paper estimates the marginal accident externality of driving in Central London by exploiting variation in traffic flow induced by the London Congestion Charge Zone using an instrumental variable approach. The charge attributed to a 9.4% reduction in traffic flow, which resulted in a less than proportional 6.0% and 7.6% decrease in accidents and slight injuries, and a 6.5% increase in serious injuries/fatalities. Our preferred estimates indicate that the accident, slight injuries and serious injuries/fatalities rate elasticities with respect to traffic flow are −0.36, −0.19 and −1.65, respectively. These estimates imply that the marginal external benefit of road safety from an additional kilometer driven is approximately £0.16. The marginal accident externality is positive, as the marginal driver along congested roads decreases the risk and severity of traffic collisions for other road users by slowing others down and increasing awareness.

中文翻译：

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驾驶事故的外部性：来自伦敦拥​​堵费的证据

本文通过使用工具变量方法利用伦敦拥堵收费区引起的交通流量变化来估计伦敦市中心驾驶的边际事故外部性。该费用归因于交通流量减少了 9.4%，导致事故和轻伤减少了 6.0% 和 7.6%，重伤/死亡人数增加了 6.5%。我们的首选估计表明，交通流量方面的事故、轻伤和重伤/死亡率弹性分别为 -0.36、-0.19 和 -1.65。这些估计表明，额外行驶一公里带来的道路安全边际​​外部收益约为 0.16 英镑。边际事故外部性为正，