Platform-mounted equipment at tube stations

[Deleted]

My friend today sent me a picture of some platform-mounted equipment found at surface stations on the LU network, asking if I could identify it:

I told him I thought this was simply a station CCTV camera and a PA speaker - although admittedly the camera does look like it's been covered over and I used to wonder about the equipment on the right myself.

Can anybody confirm whether or not I'm right? I was fairly confident, but my friend reports hearing them clicking? I assumed this was probably nothing more than something coming through the speakers or maybe the mechanism, but I was honestly not sure whether the clicking was coming from this equipment at all, it's common to hear the track go clickety-clack. But he'd be interested (and so would I have to confess) if anybody could identify the source of this mysterious clicking noise, if you know what I'm talking about?

[rincew1nd]

Hmmmm, clicking, perhaps a bird-scarer?

[theblackferret]

Could the clicking being a recording of how many people pass the equipment to use another part of the platform?

Bit like the less-sophisticated clicky buttons on car monitoring sets in the 1970's?

[Deleted]

Is it a public address speaker by any chance??

[Tubeboy]

The lower item is definitely a PA speaker. I notice there is a cable connecting the two items. So the upper item must be to do with the PA system. I'll hazard a guess. There is a small disc like structure on it, possibly a light sensor. I'm thinking that when the sun goes down, the volume of the speaker automatically goes lower. Lots of surface stations back onto property, and LU gets a lot of people complaining about noise.

[Deleted]

The item on the left is a sensor for automatic platform announcements, there is usually one towards the headwall and one towards the tail wall of the platform, if the system is turned on (very unlikely) it will detect a train in the platform and announce what station it is and what the next station will be. They do indeed make a clicking noise if you are directly in front of them!

[Deleted]

Oct 29, 2016 18:11:39 GMT @thegreenline said:

The item on the left is a sensor for automatic platform announcements, there is usually one towards the headwall and one towards the tail wall of the platform, if the system is turned on (very unlikely) it will detect a train in the platform and announce what station it is and what the next station will be. They do indeed make a clicking noise if you are directly in front of them!

Thanks a lot for this!

How does it detect the train, do you know, and what role does the clicking noise (if any) play in all this?

[crusty54]

The sensor (circular) is a motion detector.

It "sees" the train pull in and activates the announcements.