Defensive driving and the external costs of accidents and travel delays

A unified model of accident and travel-delay costs describes the role that defensive driving effort plays in balancing these costs, and the costs of effort itself. This motivates a simple method for jointly estimating risk, effort, and travel-delay externalities, which exploits ordinary travel-demand modeling to directly value the congestion that generates these costs. A unique empirical setting also allows for decomposing the joint externality into its travel-delay and accident-related components, with results suggesting that together risk and effort externalities are nearly on par with travel-delay externalities. It is also demonstrated that traditional value-of-time estimates substantially reflect risk and effort costs.