Neil Williams wrote:
On 2016-02-25 16:05:52 +0000, d said:
Because the loading gauge at platform level is about a foot narrower
than about a foot above it, also because space is needed under the
floor for engines and similar equipment on a modern MU.
Whats that got to do with making the platforms the same height as the train
floor?
The reason why the train is about a foot narrower at platform height is
because of the protrusion of the platform.
I think that's the wrong way of putting it. If the platform was at the
same height as the train floor, and of a width to just clear the train,
it's irrelevant how much narrower the train is lower down. So the platforms
need to be higher and slightly narrower. The short humps on a growing
number of Tube platforms illustrate where the whole platform should be.
The new S stock did it the other way: the trains have a lower floor, and
are narrower at that level to clear the existing platforms. That's also the
approach taken by many Continental low floor trains.