Boltar wrote:
On 13 Feb, 22:57, "Peter Corser" wrote:
The actual performance of modern stock is electronically
controllable (a set of EPROMS on the Central Line). If you are
running mixed stock and/or the signalling has not been updated the
new stock has to match (or not better) the old in performance terms
if the overlaps are not to be compromised.

But the old stock is long since gone to the depot in the sky. Surely
they could turn the wick up a bit on the new stocks by now? I can see
how the signalling would affect max line speed but I don't see why it
should limit the acceleration though.

B2003
Boltar

I'm not sure what the current status of the signalling is, but with
"traditional" LUL signalling increasing the rate of acceleration of the
train without modifying the signalling (probably requires complete new
layout, in practice) can mean that the train can arrive at any intermediate
signal travelling significantly faster than the signalled overlap speed.
The potentially increased speed aproaching the next station could compromise
the safety of the home signal.

Conventional signals were laid out based upon the speed-distance curves
supplied by the Rolling Stock Engineer. Later (more recent) practices took
more account of worst case variations in performance and gradients. There
were even some blanket overlaps (nominally 100 km/h, although the practical
application included ISTR 97 km/h overlaps to physically fit the layout) on
the original Heathrow Extension west of Hounslow West.

Peter
--
Peter & Elizabeth Corser
Leighton Buzzard, UK


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