On 23 Feb, 09:44, wrote:
On Tue, 22 Feb 2011 21:14:41 -0800 (PST)

john b wrote:
On Feb 22, 9:39=A0pm, Roland Perry wrote:
In message , at 09:43:35 on Tue, 22 Feb
2011, remarked:

It always makes me laugh when they quote "signal failure" on an ATO work=
ed
line. It seems to be a catch all excuse for any cock up.

Signal*ing* failure, perhaps? They still have to know where the trains
are, and send them instructions, even if there aren't any little red and
green lights by the trackside.

Quite. That's what "signal failure" is used to mean on the
Underground.

Except they're usually quite specific about where - "signal failure at
tottenham hale" and so forth.

And even if the signals have failed in one small area I see no reason why
the trains can't be driven manually for a short distance while being
monitored by the line controller. A somewhat better solution that just
closing an entire section of the line.

B2003

It isn't quite as simple as that. If the normal "signalling" system
fails, the system defaults to the next level of safety - manual
driving at 10mph. This is all very well but if every train has to
pass through an area where the signalling isn't responding normally at
this speed, the numbers of passengers waiting at stations quickly gets
to dangerous, even life-threatening levels. The only safe way of
dealing with this is to close parts of the line.

I'm afraid the existing lines in London can't cope with the number of
people who want to travel. It will get a little easier when Crossrail
opens but we desperately need a new South-west to North-east line
(Chelsea-Hackney). It should have been built 10 years ago but at
£300million a mile, the government didn't and still doesn't have the
money for it.
TP