Neil Williams wrote:
On Mon, 7 Mar 2005 12:16:04 +0000, Chris Tolley
wrote:

I've often wondered if DD trains really do help that much. Sure they may
move more people, but it also takes rather longer for the people to get
on and off. Is there any definitive evidence on this matter?

It was tried a long time ago (50s?) with the 4-DD sets. I think they
were restricted to one route (Dartford possibly?) and the southern
region decided that extending the platforms was a better idea.

Not sure, but given that in a 26m UIC gauge coach you only get about
1.5 times the single-decker capacity due to space taken up by what
would be underfloor equipment, staircases and wider doors, if we were
stuck with 20m British-gauge coaches you'd get even less.

Not to mention the extra foot you'd need in the loading gauge to get two
walkways one above the other. You only get about 3.7m max internal
height assuming a lower floor as low as a pocketwagon, and using the
full-height of W6 (or better yet, the freight gauges with squarer corners).

Given how full the SR is of random bridges with low clearances, and in
particular flying junctions, I doubt a loading gauge with a higher
centre will ever happen. (Improvements at the corners happen for
container traffic, but the centre never goes up...)

James Moody
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