TBTC Cabling

[trt]

Are they doubling up the cable? I've seen new stretches this morning at Euston. Anyone know why this is?

Thread title amended by superteacher for clarity.

[Deleted]

There was some ongoing work replacing loop cable where it has been cut and spliced too many times as a result of damage (dropping bits of rail on it etc.) Perhaps it is some extra cable laid out ready for installation? Definitely doesn't need doubling up (in fact I'm sure that is not technically possible).

[trt]

I'd have thought that wouldn't be possible too (doubling up). The cables would have to be perfectly in phase if they were both active simultaneously. But redundancy is the name of the game, surely. Mind you, you couldn't double up on conventional fixed block sensing either. If it is replacement of damaged loop, then they'd likely leave the old asset in place? They seem pretty close together. Wouldn't that make visual inspection and repair harder?

[Deleted]

Dec 12, 2015 8:51:57 GMT trt said:

If it is replacement of damaged loop, then they'd likely leave the old asset in place? They seem pretty close together. Wouldn't that make visual inspection and repair harder?

I don't think so. I believe the suggestion is that they've put the new loops there, ready for installation. Then, at a convenient time, they'll take the old loops out and take them away, and switch the new ones in. But having the loops already there makes the job faster because ... the loops are already there. You can just get on with the job of replacing them, no need to wait for the parts. So it's like when you see new rails lying alongside existing rails in the four foot ready for installation.

Of course, they may not take the old loops away immediately.

[trt]

The old loops have gone now. Surprised me as I'd have thought that they would get tangled up. Or I guess they just chop them. How long are these things supposed to last, I wonder?