On 19 Mar, 12:33, wrote:
AIUI FCC would not require GSM on 377s for the same reason that SN do.

The Victoria 377 problem is GSM, yes, sure, but it is for postioning
for SDO.

FCC/TL *won't be using SDO ... they do not use it anywhere on their
network pre-KO0

Yes they will!! The 377/5s are Southern units, built to Southern
specifications. Whether FCC need SDO is not relevant! One thing we
found on Southern when the 377s came in was that an 8 car 455 station
wax not an 8 car 377 station, e.g Mitcham Jnc & Battersea Park

On 20 Mar, 07:58, Standing at HN28 signal
wrote:
On 19 Mar, 12:33, wrote:

AIUI FCC would not require GSM on 377s for the same reason that SN do.

The Victoria 377 problem is GSM, yes, sure, but it is for postioning
for SDO.

FCC/TL *won't be using SDO ... they do not use it anywhere on their
network pre-KO0

Yes they will!! The 377/5s are Southern units, built to Southern
specifications. Whether FCC need SDO is not relevant! One thing we
found on Southern when the 377s came in was that an 8 car 455 station
wax not an 8 car 377 station, e.g Mitcham Jnc & Battersea Park

Why do they have to use SDO? The 377s would have to be programmed with
the station details for the FCC routes (at least London Bridge / Herne
Hill - Bedford) and this will involve surveying all the stations and
sorting out protocols for dealing with the underground stations, it
may be less work to just decommission the SDO whilst the units are
with FCC, especially if there is no location where the SDO will be
needed. The 377/5s are going to be on loan until at least 2013 and
maybe all the way to 2015, depending on deliveries of the new
Thameslink stock.

On 18 Mar, 13:20, John B wrote:
Just been to a meeting in London Bridge, for which I was 30 mins late
due to Thameslink Programme-related amusement.

Went to Farringdon to catch the 1029 to Brighton, which was initially
reported as 2 mins late, then eventually turned up at 1035. To my mild
surprise, it was a Southern-liveried 377/2 - didn't get the unit
number.

In some ways I'm annoyed I was late; in some ways I'm pleased to have
been on one of the first public service 377s on the route; in some
ways I'm glad that they're testing them in public service before next
Monday; and in other ways I'm rather worried that things are going to
go seriously titsup on Monday morning.

I have to take a train from King's Cross on Tuesday morning, and am
looking forward to taking a train from my house near Crofton Park all
the way there. I'm just hoping that the generally very reliable
service we currently enjoy from Crofton Park to Blackfriars won't be
compromised by the through London operation...

Patrick

On Mar 20, 7:58 am, Standing at HN28 signal
wrote:

FCC/TL won't be using SDO ... they do not use it anywhere on their
network pre-KO0

Yes they will!! The 377/5s are Southern units, built to Southern
specifications. Whether FCC need SDO is not relevant!



) not often I have to comment on one of your respected posts HH28 -
but what I wrote was ''FCC/TL won't be *using* SDO''.

I think I am correct in that, and your comment does not appear to me
to say anywhere FCC/TL are using it, only that the units are
equipped.

Surely that is not so much relevant as THE key point I was respondong
to ... that the Victoria 377 delay sceanrio will not arise at SPILL .

Or can you tell me where FCC/TL will be using SDO underground, and
why ?

--
Nick

On Thu, Mar 19, 2009 at 06:38:09AM +0000, Neil Williams wrote:

A more clever system could use the GPS data to derive how far the
train travels on one revolution on that day and use it later when the
GPS was not available.

You're buggered if there's the wrong type of leaves on the line though,
cos then rotations has only an approximate correspondence with distance
travelled.

--
David Cantrell | Cake Smuggler Extraordinaire

In this episode, R2 and Luke weld the doors shut on their X-Wing,
and Chewbacca discovers that his Ewok girlfriend is really just a
Womble with its nose chopped off.

On Mar 20, 11:48*am, David Cantrell wrote:
On Thu, Mar 19, 2009 at 06:38:09AM +0000, Neil Williams wrote:
A more clever system could use the GPS data to derive how far the
train travels on one revolution on that day and use it later when the
GPS was not available.

You're buggered if there's the wrong type of leaves on the line though,
cos then rotations has only an approximate correspondence with distance
travelled.


That would only apply to powered axles, but skids could affect any of
them.

On 20 Mar, 13:15, MIG wrote:
On Mar 20, 11:48*am, David Cantrell wrote:

On Thu, Mar 19, 2009 at 06:38:09AM +0000, Neil Williams wrote:
A more clever system could use the GPS data to derive how far the
train travels on one revolution on that day and use it later when the
GPS was not available.

You're buggered if there's the wrong type of leaves on the line though,
cos then rotations has only an approximate correspondence with distance
travelled.

That would only apply to powered axles, but skids could affect any of
them.

Surely it would only apply to axles where the wheelsets have brakes.
If a train 'skids', some or all of the wheels could lock up, not just
the powered ones. On modern stock, all wheelsets have brakes.

On Mar 20, 1:33*pm, wrote:
On 20 Mar, 13:15, MIG wrote:

On Mar 20, 11:48*am, David Cantrell wrote:

On Thu, Mar 19, 2009 at 06:38:09AM +0000, Neil Williams wrote:
A more clever system could use the GPS data to derive how far the
train travels on one revolution on that day and use it later when the
GPS was not available.

You're buggered if there's the wrong type of leaves on the line though,
cos then rotations has only an approximate correspondence with distance
travelled.

That would only apply to powered axles, but skids could affect any of
them.

Surely it would only apply to axles where the wheelsets have brakes.
If a train 'skids', some or all of the wheels could lock up, not just
the powered ones. On modern stock, all wheelsets have brakes.

Yes, it was a bit telegraphic wasn't it. I was inferring that the
main leaf-fall problems are to do with wheelspins, although that's not
actually in any of the words we wrote.

If there are any unpowered and unbraked axles ... not that I'm
commenting on the viability of the proposal in general.

On Fri, 20 Mar 2009, MIG wrote:

On Mar 20, 1:33*pm, wrote:
On 20 Mar, 13:15, MIG wrote:

On Mar 20, 11:48*am, David Cantrell wrote:

On Thu, Mar 19, 2009 at 06:38:09AM +0000, Neil Williams wrote:
A more clever system could use the GPS data to derive how far the
train travels on one revolution on that day and use it later when the
GPS was not available.

You're buggered if there's the wrong type of leaves on the line though,
cos then rotations has only an approximate correspondence with distance
travelled.

That would only apply to powered axles, but skids could affect any of
them.

Surely it would only apply to axles where the wheelsets have brakes.
If a train 'skids', some or all of the wheels could lock up, not just
the powered ones. On modern stock, all wheelsets have brakes.

Yes, it was a bit telegraphic wasn't it. I was inferring that the
main leaf-fall problems are to do with wheelspins, although that's not
actually in any of the words we wrote.

If there are any unpowered and unbraked axles ... not that I'm
commenting on the viability of the proposal in general.

Instead of a rev counter, how about an eddy current gizmo that measures
the passage of the rail? Same principle as a traditional speedometer:
passage of the conducting material (the rail) past the magnet (on the
gizmo) induces a force between them, which is measured by a force gauge.

Or sufficiently accurate inertial sensors. Given that trains follow highly
repetitive routes, with sufficiently clever software, they wouldn't even
need to be that accurate. It's certainly not a question of being able to
do fully general inertial dead reckoning, as on an aeroplane - you just
need to be able to tell when you've hit this curve or that station that's
listed in a database.

GPS just seems like a really bad idea for vehicles which regularly go
underground. Okay, it's fine for when they're in the open, but to build
the system round the assumption that a GPS fix will always be available is
pure madness.

The most sensible option by far would be beacons by the trackside at
stations, i suppose. These needn't be expensive - RFIDs rather than
eurobalises or something. Sensors on the train, and only open a door if
there's a beacon within a metre of it. Easy and cheap.

tom

--
In my view, this is no different than a parent introducing his child to
Shakespeare (except that the iambic pentameter is replaced by a framework
of profanity, misogyny, substance abuse, violence, retaliation, crime
and infidelity). -- Dad Gone Mad, on rap

wrote in message
...

No, because the wheels are not a fixed diameter, but get gradually
smaller as they are turned on lathes to remove flats and
imperfections. A small difference in diameter will lead to a large
cummulative error, if no corrections are made. There are other systems
which measure distance travelled (for example radar), but I don't know
how they are affected by different track formations etc.

I thought I heard that some lines work on revolutions, particularly the
Central Line.

If this is not the case, then how do Central line trains know where they
are?