Operation of Speed Check Stations
Normal speed checks should:
- be made on average week days at off-peak hours
- be made under favorable weather conditions
- include only “free floating” vehicles (see following paragraph)
- include a minimum of 125 cars in each direction at each station
- be discontinued after two hours if radar is used, or after four hours if a traffic counter that classifies vehicles by type is used — even if 125 cars have not been timed.
The vehicles checked should be only those in which drivers
are choosing their own speed (“free floating”). When a line of
vehicles moving closely behind each other passes the speed check
station, only the speed of the first vehicle should be checked,
since the other drivers may not be choosing their own speed. Cars
involved in passing or turning maneuvers should not be checked, because
they are probably driving at an abnormal rate of speed.
Trucks and busses should be recorded separately and should
not be included as part of the 125-car total.