In the small city I live in, we have small buses, which is sized right for the ridership. Unfortunately their top speed is about 26MPH on level ground and My commute includes a steep freeway overpass, which that drops to about 18MPH. The speed limit on that stretch of road is 25MPH and most traffic goes about 35MPH on the overpass as there is nowhere for a speed trap to be set. I can tell from 4 blocks away when one of those buses has been there recently.
