TWO lines on the road is a SPEED measuring device, but these are not linked to cameras so is anonymous, pre traffic census only needs and uses ONE line, two are needed to determine SPEED over the lines(TIME/DISTANCE).
Without seeing it hard to say, but if locked to lamp post, and secured witn Stainless Steel jubilee clips around the post ?, it is most likely a SPEED counter, although it measures speed, it does not have a camera so does not know who's ca ris doing what speed.
These are used to measure the speed where an application has been made to install another "CASHPOINT"(speed camera).
These are a sort of shaped box with a pent roof lid that is sited with it's flat side against the post.
These contain ANTI TAMPER DEVICES, and some are even able to leak a dye if tampered with.
If someone was to put a cable tie around the LINES of the speed detectors with the two lines they would not pass air pressure(how they work) so they wouldn't read, just athought!!
tabetha