Anyone know what those two lenses that look like telephoto lenses are that face each other on the walls of tunnels are.
I’ve always thought they were smoke or pollution detectors.
I’ve often wondered that. You can sometimes see a faint laser shining between them. I think they must be pollution detectors like Muckles said.
Yeah i would go for smoke/smog thickness detectors they probably are part of the extraction systems that a lot of tunnels have, or are there to act as a failsafe should the level of smog go beyond a certain threshold they could trigger an alarm in the control center ,
Took about 30 mins but found it in the end. 