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Comment by rsynnott | Hacker News Reader

London trains are mostly third rail powered rather than overhead line, right? You really don't want people walking on one of those. Like, you don't want people walking on any train line, but particularly not one with a third rail.

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The old-style "tube" trains are all DC third rail IIRC, but the newer trainsets such as the Elizabeth and Thameslink are all overhead AC. So this would actually be one of the few metro trains where it would be remotely safe to walk the tracks provided all the trains were stopped...

The Elizabeth line also has an actual walkway for emergency (and presumably also maintenance) purposes.

The newly built sections under central London, but lots of the Elizabeth Line is using older track.

The line by paddington has long sections where the tube runs in parallel, in one of the pictures you can see a lot of people walking towards a tune depot and somebody is crossing one of the lines with a middle rail which is part of their DC electrification system (I assume this had been turned off - but this may have been turned off because they realised people were on the line, not the other way round).

In this case, one quote I've seen is that a train's pantograph was "caught up" in the overhead wires and dragging them along, which makes it sound like some were now on the ground target than overhead.

If not all trains are stopped, aren't they in danger of collision if they remain on the train?

I'd really hope that modern signalling prevents trains entering signal blocks with other trains in (or can't confirm there's no train in) them.

As in actively prevents, locking the brakes at the previous block, rather than allowing drivers to miss or ignore signals.

We've had plenty of issues with this to learn from in the history of railways for it not to be a high priority.

E: aye seems that way :)

> In order to prevent a train from entering an occupied block, each signal has a mechanical ‘trainstop’ next to the track. This device applies the brakes of any train which tries to pass a stop signal.

https://madeby.tfl.gov.uk/2019/07/24/behind-the-scenes-signa...

The issue is during evacuation, people may not have the sense to stick to the track their train is stuck on, and may spread out into a parallel track.

That is an issue for sure, but I'm responding to the possibility of a train hitting another where the passengers have opted to stay on the halted train

The walking passengers may enter a block that their train has already cleared. So you can't really assume that wherever they walk will be locked.

The comment I'm responding to is concerned of the risks of staying on a halted train. No walkers in this hypothetical.

That is for sure an issue, but not the issue I'm responding to

No, not in the slightest.

It's very hard to tell with the Metro's haphazard writing style, but it sounds like the passengers walking on the lines were on the Elizabeth line. That's one of the Transport for London lines which uses overhead power rather than third rail.

It s probably also illegal. They could prosecute you for trespassing on the rail way if you are not supervised.

I used to commute into London before Covid and there were times when we were delayed so long that I thought we might have to resort to cannibalism.

These are mainline trains between Paddington and Acton Main Line which use overhead power lines, not a third rail as with Underground services.

fourth*. Underground uses 2 rails for power delivery. A lot of the rest of SE London/Kent uses 3rd rail.

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