Think about it, if they wanted to COUNT traffic they could do this with one line, incidentally these are PIPES that cause a pressure fluctation when squashed by a tyre, as one end is sealed and the other end goes to a little measuring device inside the black box that will be padlocked/chained to the steet lampe etc.
ONE line will detect traffic for counting purposes, TWO lines MEAUSRES THE SPEED of those vehicles, so they can see if they need/want to rip off the driver anymore, sorry to help promote safety.
They are NOT used for detection of INDIVIDUAL cars as the machine has no eyes.
Lately as these have been getting destroyed, a NEW device has appeared, fitted onto the REAR of signs this also takes the average speed readings but is mounted around 8 feet high and held with TWO Stainless Steel jubilee clips to the lamp's post .
It is a black box which when laid flat has a pent roof contructions and is locked and held by two locks on the box of tricks, that is mounted at 90 degrees to the road, and one more to hold the box to the bracket that has been secured to the pole.
These are it seems being placed where they are going to have SPEED CAMERA VANS, working on and off, FOR ROAD SAFETY!!
tabetha