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[email protected] · February 15th 11, 09:14 PM posted to uk.transport.london

In article ,
(Clive) wrote:

In message , Clive D. W.
Feather writes
There are a lot of complex electrical issues with dual-electrified
track. It isn't just a matter of sticking down some third rail,
particularly since in this case you'd be extending those issues to the
main ECML tracks as well. I'd expect fixing them to cost at least 5
million pounds based on current signalling prices. If this sort of
problem is rare, it's not going to be economically justifiable.

Surely the equipment already exists that can cope with signalling
in dual (25kV & 750V) areas, why so expensive? Or are there other
issues?

They cope only with difficulty. In DC electrified areas AC track circuits
tend to be used to avoid interference and in AC electrified areas they
tend to use DC track circuits. As you can see there is no third way to use
in dual-electrified areas. I don't know if similar considerations apply to
axle counters.

--
Colin Rosenstiel