Segways. At least, that's the part that The Economist liked so much that they put it in the headline.
My favorite part - and the emphasis is mine - comes at the end:
Alex Piquero of the John Jay College of Criminal Justice thinks the plan is a good idea, but its success “depends on what the officer is doing on the street”. Community policing and good relations with civilians are essential. Mr Nutter believes his ambitious goals are attainable. He points to New York, where violent crimes have dropped 75% over the past decade. For a city of Philadelphia's size, he reckons, homicides “should be well under 200”.
I've made the point that if we had the same crime rate as NYC, it should be under 100 but it's funny that folks in New York City, the home of John Jay College of Criminal Justice and the "Fighting Federalists," think that you can just pick up New York's crime rate and put it on any city.