On Sun, 20 Jan 2008, Mr Thant wrote:

On 20 Jan, 10:02, Paul Corfield wrote:

New trains are fitted with current system to allow migration of stock.

My understanding is the two signalling systems will run in parallel,
with the current system instructing the new one what to do.

Do you mean that the new communication system will be carrying messages
from the old control computer to the new trains? Kind of like attaching a
scan of a postcard to an email? Will the new on-train computers thus be
running an emulation of the old system's logic, or will there be a
translation step on the track side that changes "420 ppm" to "you have an
infinite clear distance ahead of you"?

I appreciate that you may not be privy to such fine details!

Incidentally, this is a great explanation of the current Vic signalling
system:

http://www.trainweb.org/tubeprune/Vi...Line%20ATO.htm

And if you've never heard of a mercury retarder, this is worth a read too:

http://www.railway-technical.com/ep-brakes.shtml

tom

--
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