On Mon, 27 Feb 2012 12:57:08 +0000, "Richard J."
wrote:
wrote on 27 February 2012 12:36:58 ...
On Mon, 27 Feb 2012 04:16:20 -0800 (PST)
wrote:
The line isn't installed yet never mind any technology but relevant
technology is already in use elsewhere; a train cannot be signalled
from the DC line to LU at Queens Park if it does not pass current
through the 4th rail.
Similar methods can prevent an LU train going to 3rd rail territory
but are AFAIAA not currently used anywhere, possibly because the
consequences are non-destructive (except for the timetable). For new
work other technology such as e.g. identification transponders could
achieve the same job.
One is aware that transponders could solve this problem. However,
AFAIK, LUL have yet to utilize such technology for the above stated
purpose.
Just out of interest , has an LU train ever accidentally been routed onto
a 3rd rail line by mistake, eg at the aformentioned locations or
gunnersbury?
At Gunnersbury, the 4th rail continues for a short distance on the up
North London Line, presumably to enable reversing moves by LU trains.
So if an LU train was accidentally routed on to the NLL, the driver
would realise this before leaving 4th rail territory.
That bit still is 4th rail territory, being available for occasional
reversing manoeuvres, described in :-
http://www.trainweb.org/districtdave...nnersbury.html
313s have reached the District Line in the past, some further than
others :-
http://www.districtdavesforum.co.uk/...=5834&pa ge=2
The LURS journal "Underground" has on at least one past occasion
published photos of a 313 sitting in splendid isolation just past the
junction waiting for a breakdown team to arrive.
OTOH I don't recall any mention of District trains going off the juice
so either the signal at the end of the 4th rail section detects the
lack of 4th rail current flow or people have been lucky so far. Things
could have been different back in the days when the DC and NL lines
were 4 rail and a train would presumably have kept going until the
driver "woke up".