Two collections of Safe System case studies are landing this summer. The Insurance Institute for Highway Safety, in partnership with the University of North Carolina Highway Safety Research Center, the Institute of Transportation Engineers, the Vision Zero Network, SafeTREC at UC Berkeley, and Fehr & Peers as a co-sponsor, will release a compendium of Safe System case studies at the ITE International Conference in Detroit. A second collection appears in the NCHRP 08-171 Safe System Institutionalization Toolkit, releasing in June. Both efforts trace projects that have measurably reduced crash injury risk through the three levers of the Safe System Approach: exposure, severity, and likelihood.

Working on these case studies clarified something we have been seeing in our own projects for a while. The cases that produced the most durable safety gains were not the ones that pulled the hardest on a single lever. They were the ones where an intervention package pulled all three at once, with each component making the others work harder.

We are calling that pattern a safety multiplier. San Francisco’s Van Ness BRT is a useful example: a transit-only lane that simultaneously reduced vehicle volumes, slowed remaining traffic, removed conflict points, and improved emergency response. One project, multiple wins reinforcing each other.

We have put together a page that explains the multiplier concept, walks through Van Ness to illustrate it, and catalogs eleven other multipliers we have been tracking such as congestion pricing, road diet or road reconfiguration packages, Safe Wave signal timing, Safe Routes to School networks, and others. It includes a quick-reference table showing which lever each one emphasizes, so a decision maker can select from the best fitting ideas for their local context.

If you are at ITE Detroit, you’ll see us on a series of plenaries, panels, poster sessions, and roundtable discussions showcasing Safe System and people-centered mobility. We hope to see you there. And if you are working on leveling up Safe System impacts for your community, where one of these patterns might fit, we would be glad to talk it through.