4 Answers

The term speed trap has several meanings, related to detection of speed limit violations.

• It can refer to a place where a road-rule enforcement camera is posted.


• California traffic law formally defines a certain kind of "speed trap" which is forbidden to be used by police officers as an evidence.


• Still another meaning is a specific location in which police wait in concealment, hoping to catch unwary motorists speeding. For example, a police car might wait behind a bridge or overpass, out of sight of approaching motorists, then pull out once they pass. Often, this type of operation uses a radar gun to track cars' speeds.


• Most commonly, it refers to strict enforcement speed limits using techniques or criteria which evidence suggests aren't purely motivated by road safety.

Disproportionately strict enforcement

Some cities or sections of road become known as speed traps when police have a reputation for writing an unusually high number of traffic tickets, usually for speeding. Sometimes, the posted speed limits are not easily seen; in other places, police have chosen to strictly enforce speed limits, and the limits might be set lower than warranted by road conditions or population. Speed traps often are found in small towns, often near major highways, in which travellers are unlikely to return to challenge a speeding ticket.

Some communities with reputations as speed traps have a disproportionately large number of their local workforce involved in law enforcement or judiciary occupations.

In some small towns and counties, traffic fines make up a large fraction of the income of the local government, which gives the police an incentive to write tickets.

Yet another tactic is for police to catch unwary motorists speeding by waiting behind bridges, overpasses, out of sight of approaching motorists, then pull out once they pass.

tell it to the judge!

www.speedtrap.org..

Not sure that it matters.  If a speed limit is posted, seems to me that is the speed you are to use as a maximum.