Making an economic case for prevention: A cost-benefit analysis for pedestrian safety

Background: Auto-versus-Pedestrian (AVP) injuries comprise 25% of trauma cases in San Francisco. To support an economic case for injury prevention, we conducted a benefit-cost-analysis (BCA) of installation and maintenance costs for an effective engineering countermeasure and the direct medical costs of AVP injuries occurring between 2004 and 2008. We predicted that the Pedestrian-Countdown-Signal (PCS) would yield a future benefit for at least 30% of intersections with a history of hospital admitted injuries, while intersections with police-reported-only injuries would yield no benefit. Methods: We matched hospital, police, and transportation data to identify intersections where injury collisions had occurred and PCS devices were missing. Using a nationally recommended index, we calculated a benefit-cost ratio that included PCS effectiveness and installation costs, estimated traffic growth rates, and injury cost data. When available, we used actual injury cost per incident. Otherwise, we assumed a median outpatient treatment cost of $6400. We collapsed collision incidents to an intersection unit of analysis. Results: We identified 371 incidents and collapsed them to 193 intersections. 47 intersections had a history of hospital admitted injuries and 40% of these were cost-beneficial. The median benefit for cost-beneficial intersections was $2.85. No intersections with police-reported-only injuries (n=146) were cost-beneficial. Conclusions: We found that the injury cost savings for every $1.00 spent on implementing PCS at cost-beneficial locations would be $1.85. Our results exemplify a “bottom-line” approach to prioritizing investments aimed at increasing pedestrian safety during economically scarce times. Systematic data linking of hospital, police, and transportation sources would improve future BCAs.