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Comment by Jesus_Jones | Hacker News Reader

I've always wondered, why don't they have fences a few feet from the edge of the platform, with many open gates? Then you could stand at the fence without being able to be pushed into the train's path. Since they aren't on the edge, you could get off the train okay. It would reduce free movement but would not matter unless there was heavy traffic - and in that case, it would be welcomed, by me at least.

Let's see if I can do this with ascii art, just for fun:

   [trains, edge of tracks below]

==========================================================

--- -------- -------- -------- ------- fence line

   (people, crowds .................................)

View on HN

In London TFL is looking to deploy more track side doors, which are similar.

I can’t speak for other cities, but in London many platforms are simply too narrow for a few feet of the platform to be cordoned off.

Additionally the other issue with overcrowding is emergency and disaster response. If the fire alarm goes off, you need to get all those people too the surface, without anyone being crushed or trampled (look at the Hillsborough disaster to see what happens when you get to wrong). I suspect that people being pushed onto the track is minor concern compared to what happens if people start to panic.

This article would justify a submission of its own but is so spot-on in reply to your comment; here we go:

https://www.newyorker.com/magazine/2011/02/07/crush-point

This is common in modern systems with consistent lengths of trains and cars, consistent door placement, and a consistent stopping place.

But outdated systems like NYC's doesn't have consistent alignment when stopping, so it would be difficult for the train car doors to line up with the gaps in the fence (or wall/screen).

Here's how it should work in any modern system or system to be upgraded: http://blog.lareviewofbooks.org/wp-content/uploads/2015/12/K...

That's what they do in Hong Kong, a nice glass barrier. Solves the trash on the tracks problem, plus people can't fall down there.

My guess is that requires a precise stopping position, which requires a proper control system, which they probably don't have.

What you’re suggesting would be a system similar to what is used today on rollercoasters.

Is it? I haven’t been in one recently, but I would get people out on one side, and in on the other (which typically isn’t possible in existing subway tunnels)

Rollercoasters have a few other advantages:

- exits at every row of seats.

- less crowded (no standing passengers, never three people on a two seat bench)

- at every stop, everybody gets out, and everybody gets in.

- passengers typically are relatively fit (no small kids, no elderly)

- no luggage.

That simplifies the process quite a bit.

Of course, but rollercoasters also frequently have much more money to spend on security features, so technology first seen there shows up a while later in public transit.

E.g., modern signalling that replaces the old block signalling, or the station door systems to let people in/out which now are also in major subways around the world.

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