In message
, at
10:27:16 on Tue, 11 Dec 2007, Old Central
remarked:
OK then - could you fit two island platforms in the box? Based on my
crude maths and assuming straight track and a 6m existing platform -
no end or centre throws - the latter is definitely not true at the
south end or where S&C may affect the layout at the north end. It also
ignores S&C to achieve 4 parallel tracks not 2.

Platforms = 6.000m *2 = 12.000m
Track = 1.435m *2 = 2.870m
Track to platform 0.730m *2 = 1.460m
Six foot = 1.970m

Width of box = 18.300m approx.

For two islands you would need
Track = 1.435m *4 = 5.740m
Six foot = 1.970m
Cess=1.250m (minimum)*2 = 2.500m
Track to platform = 0.730m*4 = 2.920m

This would leave two platforms of width 2.585m - the HMRI minimum for
a single face platform is 2.5m. So no.

I've found the following Arup Journal article, which has all kinds of
diagrams (and text) which answer many of the questions we've been
wondering about. Including much of the history of why it was done the
way it is (maybe we can now nickname the Champagne Bar "Platform 4"?)

Figure 14 does seem to show that there's a possibility for two islands,
albeit with a fairly thin platform; and why else would it be that wide?

http://www.arup.com/_assets/_download/download238.pdf
--
Roland Perry