Each year, traffic crashes kill more than 1.2 million people around the world and injure up to 50 million. In fact, they are the leading cause of death among people 15 to 29 years old and cost the global economy around $518 billion. Many of these casualties are preventable, but governments can have difficulty knowing where to begin. There are tested ways to improve road safety, but a lot of them are not widely known, so it’s challenging to find all available countermeasures, sort through them, and determine which are most relevant for a particular area. With ever-tighter budgets facing national governments and localities—which have primary responsibility for traffic laws, vehicle-safety regulations, and developing and maintaining road infrastructure—they often must make difficult choices.

We have developed a road-safety cost curve that makes it possible to compare the impact and expense of different road-safety countermeasures and researched more than 200 of them in the academic and corporate literature. A European city that has been using our approach plans to invest approximately €5 million a year through 2020 in a variety of prioritized countermeasures expected to cut traffic fatalities and severe injuries in half. A large proportion of these investments will be funded by reallocating resources already in the budget, not new money. Ultimately, the program will be cost negative, saving the city about €60 million a year.