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Graeme[_2_] · August 17th 10, 03:24 PM posted to uk.transport.london,uk.railway

In message
d wrote:

On Tue, 17 Aug 2010 07:16:21 -0700 (PDT)
Andy wrote:
It's not daft to build a train to fit the more modern infrastructure
on the Victoria line, the 2009 stock would never be able to run on any

The reason AFAIK that the victoria line tunnels were built larger was to
reduce air resistence and make the trains more efficient. Presumably at
least part of those savings have now been lost due to the bigger trains.

[snip]

The Victoria Line booklet[1] published by LT in 1969 states that it was
discovered that opening out the tunnels to 12'6" (from 12') did indeed reduce
the air drag to a degree comparable to that of open-air operation. However
it is emphatic that that was not a design criterium. Minimum tunnel diameter
is actually 12'2" so there will be little losss of efficency in practice.

[1] The Story of the Victoria Line by John R Day. P28

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Graeme Wall

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