The bureaucrats running Mumbai’s suburban rail network had a problem: Commuters and people living and working close to train stations were taking shortcuts across the tracks. This reckless behavior was causing 6,000 deaths in the metropolitan area every year. The transit authorities asked FinalMile, a local marketing consultant, to find a solution. FinalMile had experience in applying behavioral economics to sell consumer goods; the city hoped it could use similar techniques to save lives. FinalMile would do the work for free.