New York Metro's Rat Detector App

The rat detector has appeared in the Transit app of the New York Metro. Users themselves report the number of rodents. When planning a route, they are asked if there are rats at the station, and they can answer: a lot, a couple of them, or none at all. The authors of Transit also conducted a study to identify the most rat-infested station, with 191st Street between Broadway and Seventh Avenue winning the title.