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Comment by Reason077 | Hacker News Reader

In London there are platforms which are shared between lines that use trains with completely different proportions, car lengths, and door spacing. Even with half-height doors it would be difficult to come up with a system that could handle both the small deep-tube trains of the Piccadilly line and the large, sub-surface trains of the District line.

Other metros around the world that have retrofitted PEDs had the advantage of having fleets of trains with standardised dimensions.

Of course, this wouldn't stop them selectively installing platform edge doors at stations that do not have this issue. The most modern lines (central section of the Elizabeth line, and the eastern section of the Jubilee line) do have PEDs.

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Step one, standardize the doors. Step two, wait 30 years until the non standard door train is replaced.

Or just put 2 doors on the barrier

that works if there are only two different door layouts. as you get more you run into the door support for on train being in the wayof a door for another. Even for two layouts sometimes you need platform doors very wide doors two cover two.

Yes I acknowledge the differences.

We could still install PEDs with imprecise doors. Ie more doors than required. Larger doors than required. The main thing is for the door to only open while a train is in front of it, and all the train doors be unobstructed.

Ie won’t hurt much to have a PED open to the train wall or opens double the size of the current trains’ door.

> "Ie won’t hurt much to have a PED open to the train wall or opens double the size of the current trains’ door."

I imagine there would be safety issues with that approach since it might create an opportunity for people to get trapped between the platform doors and the train. No sense solving one safety issue just to introduce another one. You'd also need to be sure the platform doors didn't take any longer than the train doors to open. Anything that increases boarding & alighting time, even by a second or two, would likely be rejected in London.

There’s already plenty of instances of the JLE doors opening out of sequence, misaligned etc. hasn’t stopped TfL from using them.

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