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Clive D. W. Feather[_2_] · May 16th 11, 10:10 PM posted to uk.transport.london

In message , d
wrote:
The 95 stock were slugged on arrival to prevent them being able to run
faster than the 59 stock then on the line. This was supposed to be removed
when all the 59 stock had gone. This was then changed to "it will be
removed when the new signalling comes in".
I don't understand the logic behind that. Surely they'd want the trains to
have the maximum possible performance for when it can be used? eg going up
the steep incline from archway to highgate or the long run from east
finchley to finchley central?

The signalling may have been designed with certain assumptions in (e.g.
"a train passing Archway at 5mph won't exceed 20mph at signal XYZ").
Changing the train characteristics could invalidate those assumptions.

IIRC there was a collision or derailment near Watford Junction because
modern rolling stock invalidated the signalling design assumptions.

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Clive D.W. Feather | Home:
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