Speed drops from 55mph to 50mph 1/10th of a mile north of Phoenix, just south of police/fire station, so there is lots of police traffic in that area. Most people are not paying close attention to speed limit signs when they are that close to approaching an intersection & already slowing somewhat to make a turn or preparing to stop at the intersection. I received a ticket claiming I was in the 50mph zone, when I was not yet there.