This mobile restroom initiative was designed as a solution to San Francisco's poop problem. Ariel Schwartz of Fast Company's CoExist explains how the city "suffers from an excess of excrement on public streets and even in the innards of subway escalators, where it renders them unusable." The city's large homeless population (which are a contributing fecal factor) can kind relief at a Tenderloin Pit Stop -- a public bathroom on wheels.
Available during the day each mobile restroom has an attendant waiting outside and contains a sink, two toilets, a dog waste station and needle disposal bin. Attendants give people five minutes to do their business. Then at night the Department of Public Works takes the toilets away for cleaning.
Web developer Jennifer Wong also created a map indicating where particularly poopy public plates are.