How can you have a signal failure on an ATO system?
 

Came back from holiday today to be greeted by the usual tube **** up.
Signal failure on the Victoria line. Something that I hadn't wondered
before is how exactly can you have a signal failure on a line thats
controlled by ATO via a leaky feeder cable? The light signals are
AFAIK there simply as extra information for drivers and arn't really
required anyway so if one fails so what? The train is control by the
ATO cable signals , not a cluster of coloured lights in the tunnel. Or
is "signal failure" just an LU catch all phrase for a computer
failure?

B2003

How can you have a signal failure on an ATO system?
 

On Aug 22, 8:05 pm, Boltar wrote:
Came back from holiday today to be greeted by the usual tube **** up.
Signal failure on the Victoria line. Something that I hadn't wondered
before is how exactly can you have a signal failure on a line thats
controlled by ATO via a leaky feeder cable? The light signals are
AFAIK there simply as extra information for drivers and arn't really
required anyway so if one fails so what? The train is control by the
ATO cable signals , not a cluster of coloured lights in the tunnel. Or
is "signal failure" just an LU catch all phrase for a computer
failure?

B2003


I always thought that it kind of meant "track/circuit failure
resulting in signals going red".

I suppose signals must be able to fail in some sense, but I don't
think signal failures often mean anything other than signals doing
their job correctly when something else fails.

How can you have a signal failure on an ATO system?
 

Boltar wrote:
Came back from holiday today to be greeted by the usual tube **** up.
Signal failure on the Victoria line. Something that I hadn't wondered
before is how exactly can you have a signal failure on a line thats
controlled by ATO via a leaky feeder cable? The light signals are
AFAIK there simply as extra information for drivers and arn't really
required anyway so if one fails so what? The train is control by the
ATO cable signals , not a cluster of coloured lights in the tunnel. Or
is "signal failure" just an LU catch all phrase for a computer
failure?

AFAIK the victoria is not computerised ATO. I works using mechanical
odometry and still relies on a block signalling system. It outdates
viable computers by a decade or two.

I could be wrong...

Tony

How can you have a signal failure on an ATO system?
 

On Aug 22, 8:05 pm, Boltar wrote:
The train is control by the ATO cable signals , not a cluster of coloured
lights in the tunnel. Or is "signal failure" just an LU catch all phrase for
a computer failure?

Yes. For reasons I can't remember, there are only something like 5 or
6 possible phrases they'll use to explain delays to the public.
"Signal failure" is very broad and could mean any kind of signalling/
ATO/points/etc problem. "Passenger action" is another one.

U

--
http://londonconnections.blogspot.com/
A blog about transport projects in London

How can you have a signal failure on an ATO system?
 

Boltar wrote:
Came back from holiday today to be greeted by the usual tube **** up.
Signal failure on the Victoria line. Something that I hadn't wondered
before is how exactly can you have a signal failure on a line thats
controlled by ATO via a leaky feeder cable? The light signals are
AFAIK there simply as extra information for drivers and arn't really
required anyway so if one fails so what? The train is control by the
ATO cable signals

Haven't you just answered your own question?

How can you have a signal failure on an ATO system?
 

On Aug 22, 8:52 pm, Tony Chung tony@invalid wrote:
Boltar wrote:
Came back from holiday today to be greeted by the usual tube **** up.
Signal failure on the Victoria line. Something that I hadn't wondered
before is how exactly can you have a signal failure on a line thats
controlled by ATO via a leaky feeder cable? The light signals are
AFAIK there simply as extra information for drivers and arn't really
required anyway so if one fails so what? The train is control by the
ATO cable signals , not a cluster of coloured lights in the tunnel. Or
is "signal failure" just an LU catch all phrase for a computer
failure?

AFAIK the victoria is not computerised ATO. I works using mechanical
odometry and still relies on a block signalling system. It outdates
viable computers by a decade or two.

I could be wrong...

Tony

You are correct there.
The only line that use computer and non-mechanical (SSI/Relay etc)
signalling is the Central. The Jubilee does too between Green Park
and Stratford, but still uses Train Stops.
The other lines that have computers operating mechanical signalling
equipment are Bakerloo and the Circle Signalling centre (Stanmore-
Charing Cross and Wembley Park-Aldgate (Minories/Aldgate East)) and
the Piccadilly line north of Wood Green.

As to the term Signal Failure. This is a blanket term for any failure
of the signalling system (except where it is multi-site caused by the
same problem, where it is know as a Signalling System Failure). It is
mainly used where the failure is down to the Infraco or Network Rail.
Where LUL are at fault, such as a SPAD or Wrong Signal Lowered and
Accepted, it is put over as a Signalling Problem.

How can you have a signal failure on an ATO system?
 

Are the signals that are normally found on the upper left side of the tunnel
entrances at Victoria line stations actually starter signals or are they
platform repeaters? I notice that the stations do not appear to have
track-level starters, execpt for areas where there are points, such as at
Victoria.

I realise that the various equipments differ, but I it seems that signal
aspects on the Victoria line are the same as those on the Central line.
These include a danger aspect, an aspect allowing trains on code to proceed
and a clear aspect for all trains.

In any event, I notice that many drivers on the Central and Victoria lines
prefer to wait until they get a full clear before closing up and proceeding,
although some will depart when the signal indicated clear for coded trains.
Why is that?

How can you have a signal failure on an ATO system?
 

wrote:
Are the signals that are normally found on the upper left side of the
tunnel entrances at Victoria line stations actually starter signals
or are they platform repeaters? I notice that the stations do not
appear to have track-level starters, execpt for areas where there are
points, such as at Victoria.

I realise that the various equipments differ, but I it seems that
signal aspects on the Victoria line are the same as those on the
Central line. These include a danger aspect, an aspect allowing
trains on code to proceed and a clear aspect for all trains.

In any event, I notice that many drivers on the Central and Victoria
lines prefer to wait until they get a full clear before closing up
and proceeding, although some will depart when the signal indicated
clear for coded trains. Why is that?

The platform headwall corner signals are "true" starters. A Vic line train
running in usual ATO mode will not normally pass a red signal (white aspect
shown when an ATO train can pass, but train in manual cannot). The same
thing is true where signals are ptrovided away from stations (usually
confliction point protection or where there are more than one route from the
signal). Headway posts are not intended to be stopped at by non ATO trains.

The corner signals realy become significant in degraded mode where manual
driving is necessary or if non ATO equipped works trains are running on the
line outside a possession (not sure if that is still allowed).

The existing Vic line signalling (due for replacement in the near future)
uses coded track circuits with a very restricted number of codes (3 running
codes for 2 train running speeds and 1 "code" only identified as part of the
signalling system).

Being pedantic the Vic Line mixes ATO with ATP (automatic train
protection) - the latter is, in very broad terms, the auto equivalent of
the fail safe signalling system.

Peter
--
Peter & Elizabeth Corser
Leighton Buzzard, UK

How can you have a signal failure on an ATO system?
 

On Wed, 22 Aug 2007 13:17:07 -0700, Mr Thant
wrote:

On Aug 22, 8:05 pm, Boltar wrote:
The train is control by the ATO cable signals , not a cluster of coloured
lights in the tunnel. Or is "signal failure" just an LU catch all phrase for
a computer failure?

Yes. For reasons I can't remember, there are only something like 5 or
6 possible phrases they'll use to explain delays to the public.
"Signal failure" is very broad and could mean any kind of signalling/
ATO/points/etc problem. "Passenger action" is another one.

"Signal failure" is at least meaningful (though posibly slightly
misleading). The phrase "passenger action" deserves to be sent to the
same hell to which I would banish all management speak. ("There's no I
in team" -- "Unless you're French", I always reply.)

How can you have a signal failure on an ATO system?
 

On Aug 22, 9:42 pm, "John Rowland"
wrote:
Haven't you just answered your own question?

No. If it was a signal failure why couldn't the trains still run? If
it was an ATO failure then how could anything run?

B2003

How can you have a signal failure on an ATO system?
 

Boltar wrote:
On Aug 22, 9:42 pm, "John Rowland"
wrote:
Haven't you just answered your own question?

No. If it was a signal failure why couldn't the trains still run?

Because there's only one signalling system. It's the usual LU fixed-block
system; there isn't an independent system for ATO, as you seem to think.
There's a good description of how the Victoria Line works on the Tubeprune
site at
http://www.trainweb.org/tubeprune/Vi...Line%20ATO.htm

--
Richard J.
(to email me, swap 'uk' and 'yon' in address)

How can you have a signal failure on an ATO system?
 

On Aug 23, 10:12 am, "Richard J." wrote:
Boltar wrote:
On Aug 22, 9:42 pm, "John Rowland"
wrote:
Haven't you just answered your own question?

No. If it was a signal failure why couldn't the trains still run?

Because there's only one signalling system. It's the usual LU fixed-block
system; there isn't an independent system for ATO, as you seem to think.
There's a good description of how the Victoria Line works on the Tubeprune
site athttp://www.trainweb.org/tubeprune/Victoria%20Line%20ATO.htm

Interesting site , but it doesn't explain how the ATO and ATP are
seperate if they both rely on the track codes.

B2003

How can you have a signal failure on an ATO system?
 

On Aug 22, 9:43 pm, chunky munky
wrote:
On Aug 22, 8:52 pm, Tony Chung tony@invalid wrote:
The Jubilee does too between Green Park and Stratford, but still
uses Train Stops.

I thought that the Jubilee ext was conventional signalling. They are
installing a loop system as we speak but that wont be up and running
for a few years and quite a few years given progress to date. One of
those wonderful Tubelines jobs that are on schedule and on cost,
according to the Mayor.

Kevin

How can you have a signal failure on an ATO system?
 

"Peter Corser" wrote in message
...

The platform headwall corner signals are "true" starters. A Vic line
train running in usual ATO mode will not normally pass a red signal (white
aspect shown when an ATO train can pass, but train in manual cannot).

I was referring to the white aspect in my earlier post, not the red one. I
was wondering why some drivers chose to hold at a station, even if they have
a white aspect.

The same thing is true where signals are ptrovided away from stations
(usually confliction point protection or where there are more than one
route from the signal). Headway posts are not intended to be stopped at
by non ATO trains.

What is a headway post?

How can you have a signal failure on an ATO system?
 

"Kev" wrote in message
ups.com...
On Aug 22, 9:43 pm, chunky munky
wrote:
On Aug 22, 8:52 pm, Tony Chung tony@invalid wrote:
The Jubilee does too between Green Park and Stratford, but still
uses Train Stops.


Doesn't the same situation apply on the Northern line and on the Drain?

How can you have a signal failure on an ATO system?
 

On Thu, 23 Aug 2007 21:28:49 GMT, wrote:

The platform headwall corner signals are "true" starters. A Vic line
train running in usual ATO mode will not normally pass a red signal (white
aspect shown when an ATO train can pass, but train in manual cannot).

I was referring to the white aspect in my earlier post, not the red one. I
was wondering why some drivers chose to hold at a station, even if they have
a white aspect.

Because they're driving in manual?

How can you have a signal failure on an ATO system?
 

"asdf" wrote in message
...
On Thu, 23 Aug 2007 21:28:49 GMT, wrote:

The platform headwall corner signals are "true" starters. A Vic line
train running in usual ATO mode will not normally pass a red signal
(white
aspect shown when an ATO train can pass, but train in manual cannot).

I was referring to the white aspect in my earlier post, not the red one. I
was wondering why some drivers chose to hold at a station, even if they
have
a white aspect.

Because they're driving in manual?

I've seen them driving in ATO and holding even when they have a white
aspect, at least on the Central line.

Even if they are driving in manual they would have to be on code, and even
then they would be able to proceed on a white aspect.

How can you have a signal failure on an ATO system?
 

wrote:
"Peter Corser" wrote in message
...

The platform headwall corner signals are "true" starters. A Vic line
train running in usual ATO mode will not normally pass a red signal
(white aspect shown when an ATO train can pass, but train in manual
cannot).

I was referring to the white aspect in my earlier post, not the red
one. I was wondering why some drivers chose to hold at a station,
even if they have a white aspect.

The same thing is true where signals are ptrovided away from stations
(usually confliction point protection or where there are more than
one route from the signal). Headway posts are not intended to be
stopped at by non ATO trains.

What is a headway post?

The signal is part of the ATP function - it merely tells the driver that he
has the appropriate code and authority to pass that signal, not that he must
pass it. This is identical to a normal procede aspect in manual signalling.
ATO and ATP functions are not fully separated as is usually done with
current systems.

Driver holding at white could be in manual, but may just be running early
(or realise that he is running too close to the one in front - holding at
white for a short period may mean that he can have an unchecked or better
run to the next station/s). If he is running early he will only be held for
time at the next controlled signal site (signals clear on route and time,
among other factors).

Headway posts were installed in the Vic as a means of informing a driver
that he had been stopped in ATO/ATP due to the train in front. These were
the equivalent of intermediate and home signals, but a genuine signal was
only installed where there was a routing consideration. A non ATO/ATP train
could not be signalled to approach a headway post and be stopped at it.

AFAIR the white aspect came up on the corner signal as soon as a 270 code
(medium speed, but allowed remotoring) was available to the train in the
platform. The green was a genuine LUL green - only allowed once the
preceding train had cleared an "overlap" on the next signal (it wasn't
called an overlap, but fulfilled the same function). The codes were 420
pulses per minute = full speed allowed, 270 + medium speed with motoring,
180 = medium speed coasting only, 0 = only used by signalling system.

The station stop was achieved by an initial braking spot followed by a
sequence of spots with the speeds mimicking the braking curve to rest in the
platform. ISTR that the sequence was set in 5 mph steps with the spot
frequency indicating the allowed speed - there were three brake rates with
the braking curve assuming that the "normal" middle rate would be OK. The
only way to easy adjust the curve was reposition a spot (and there was much
fine tuning in the early days).

Peter
--
Peter & Elizabeth Corser
Leighton Buzzard, UK

How can you have a signal failure on an ATO system?
 

Kev wrote:
On Aug 22, 9:43 pm, chunky munky
wrote:
On Aug 22, 8:52 pm, Tony Chung tony@invalid wrote:
The Jubilee does too between Green Park and Stratford, but still
uses Train Stops.

I thought that the Jubilee ext was conventional signalling. They are
installing a loop system as we speak but that wont be up and running
for a few years and quite a few years given progress to date. One of
those wonderful Tubelines jobs that are on schedule and on cost,
according to the Mayor.

I guess what has been left out is that this was supposed to have been
done before the line opened, but slipped so much they had to give up to
allow the line to open on time...

Tony

How can you have a signal failure on an ATO system?
 

In article , Peter Corser
writes
AFAIR the white aspect came up on the corner signal as soon as a 270 code
(medium speed, but allowed remotoring) was available to the train in the
platform. The green was a genuine LUL green - only allowed once the
preceding train had cleared an "overlap" on the next signal

No. From memory the signal shows white when the line is clear to the
next headway post plus overlap and green when it is clear to the next
signal plus overlap. A station starting point would only produce a 420
code, not a 270 - 270 allows restarting at a signal stop but not from a
station. White would only be displayed with a 420 code.

The codes were 420
pulses per minute = full speed allowed, 270 + medium speed with motoring,
180 = medium speed coasting only, 0 = only used by signalling system.

120, not 0.

--
Clive D.W. Feather | Home:
Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org
Fax: +44 870 051 9937 | Work:
Please reply to the Reply-To address, which is:

How can you have a signal failure on an ATO system?
 

In article . com,
Boltar writes
Interesting site , but it doesn't explain how the ATO and ATP are
seperate if they both rely on the track codes.

They're different functions within the train.

The ATP relies on the four basic codes. It picks them up and, in
essence, generates a set of permissions to the rest of the train:
"can move", "can accelerate", "can start from station", "can start
within tunnel", "maximum speed is X". These are then combined with the
current state of the train to provide the two controls of "disable
motors" and "apply emergency brakes". Thus the ATP only ever stops the
train.

The ATO takes the permissions from the ATP box, the commands from the
command spots ("speed X", "coast", "brake"), distances from the
odometer, and the map of the railway stored within the Auto Driving Box,
to actually control the train. Thus if it sees the command spot "speed
40" from the track but "maximum speed is 25" from the ATO, it will
accelerate or brake to 25. It relies indirectly on the four basic codes,
but only via the ATP, not by picking them up itself.

--
Clive D.W. Feather | Home:
Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org
Fax: +44 870 051 9937 | Work:
Please reply to the Reply-To address, which is: