AZ Highway Patrol like to lurk back up the southbound entrance ramp, hidden from view until it’s too late. Confusion is compounded by the fact that signals frequently trip Ka band detectors when no police are present, causing frequent travelers to get lax and ignore the detector signal. Speed limit is 75 and traffic speed is frequently 80-85. AZ HP seem to be only looking for serious speeders, at least in Phoenix area and points north.