speed trap

Hi i was driving home this afternoon and see a police van situated ontop of the bridge junction 1 of the m40 near denim.they where there this morning and still there at 4pm this evening beware people.also a blue unmarked van was on the a40 juction 3 of the m40 near the tescos roundabout london road facing away from cars going towards high wycombe big camera sticking out the rear window it was there friday they usualy put a trap there every 2 to 3weeks