Sidewalks, bike lanes, traffic calming projects — they save lives. Not just by protecting cyclists and pedestrians (not to mention motorists), but by encouraging physical activity that leads to a healthy life.

Of course, it can be hard to convince politicians to see things in those terms when it’s time to pony up for walking and biking infrastructure. That is the brilliance of this new tool from the World Health Organization.

The WHO, which is on a mission to rein in the worldwide epidemic of traffic deaths and injuries, has developed a tool that measures the health impacts of bike and pedestrian infrastructure projects, calculating cost-benefit analyses as well as the economic value of reduced mortality.

Of course you need to do a little advance preparation before using the tool. You’ll need to have a fair amount of information about local travel habits at your disposal. (For example, you’ll be prompted to estimate the percentage of people who currently take walking trips and the average length of the trip.) But it’s the type of info your local metro planning agency should have publicly available. Worst case scenario, you have to perform a survey.

The tool is recommended for planners and engineers as well as advocacy groups.