Dartford tunnel boxes?

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
1

Dose any one know what the silver boxes are in the tunnel are :question: .They look like bird nesting boxes.
They are on the roof of the low tunnel about ever 7 yards.

2

I haven’t noticed them, but are they smoke detectors?

If you look on the left hand walls there are fog detection guns mounted on the wall

3

Wheel Nut:
I haven’t noticed them, but are they smoke detectors?

If you look on the left hand walls there are fog detection guns mounted on the wall

I have no idea but why would you put a smoke detector in a box :question: .I was excepting little birds to come
flying out of them :laughing: :laughing:

4

canaries, if you see a wing hanging out of it, the bird is dead there is no air left and your all gonna dieeeeeeeeeeeeeee :smiley: