On 18/08/2010 12:13, Roland Perry wrote:
In message
, at
03:20:43 on Wed, 18 Aug 2010, martin remarked:
Something that I don't think had previously been released:
The crew of the grinding unit, who had no means of re-applying the
brake, jumped off the unit as it passed through Highgate station.

The "jumping off" was known, but not the bit about the brake.

I heard that it was at Archway.

On Wed, 18 Aug 2010, martin wrote:

On Aug 13, 12:00*pm, Mizter T wrote:
On Aug 13, 11:23*am, Paul wrote:

Sounds like a serious screw up, thankfully no-one got hurt. RAIB will
of course be involved.

The RAIB have announced their investigation, with some preliminary
details and a picture of the unit involved:
http://www.raib.gov.uk/publications/...te_runaway.cfm

Thanks for that, i'm sure we all look forward to reading the report.

Something that I don't think had previously been released:

The crew of the grinding unit, who had no means of re-applying the
brake, jumped off the unit as it passed through Highgate station.

J. Jesus Krispy Kreme Christ on a Borisbike!

'no means of re-applying the brake' is a rather frightening phrase. I
would hope trains were not constructed in such a way that this could ever
be the case, but they are evidently not. Indeed, AIUI, air brakes work by
having a reservoir on each car that drives brake application when the
pressure in the brake pipe drops, but if there is no compressor in action,
as here, then this reservoir will be empty, and there will be no pressure
to apply the brakes even in the absence of brake pipe pressure. Seems like
a bit of a loophole in the fail-safety, but i'm not sure what else you can
do. Presumably a spring does not supply enough force to apply the brakes!

tom

--
I really don't know what any of this **** means, but it looks
impressive. -- zerolives, on YVFC

On 18/08/2010 22:15, Tom Anderson wrote:
On Wed, 18 Aug 2010, martin wrote:

On Aug 13, 12:00 pm, Mizter T wrote:
On Aug 13, 11:23 am, Paul wrote:

Sounds like a serious screw up, thankfully no-one got hurt. RAIB will
of course be involved.

The RAIB have announced their investigation, with some preliminary
details and a picture of the unit involved:
http://www.raib.gov.uk/publications/...te_runaway.cfm


Thanks for that, i'm sure we all look forward to reading the report.

Something that I don't think had previously been released:

The crew of the grinding unit, who had no means of re-applying the
brake, jumped off the unit as it passed through Highgate station.

J. Jesus Krispy Kreme Christ on a Borisbike!

'no means of re-applying the brake' is a rather frightening phrase. I
would hope trains were not constructed in such a way that this could
ever be the case, but they are evidently not. Indeed, AIUI, air brakes
work by having a reservoir on each car that drives brake application
when the pressure in the brake pipe drops, but if there is no compressor
in action, as here, then this reservoir will be empty, and there will be
no pressure to apply the brakes even in the absence of brake pipe
pressure. Seems like a bit of a loophole in the fail-safety, but i'm not
sure what else you can do. Presumably a spring does not supply enough
force to apply the brakes!

tom

What about the parking brake, if at least to bleed off momentum?

In article , (Roland
Perry) wrote:

In message , at
08:00:08 on Wed, 18 Aug 2010, remarked:

That makes me wonder why they didn't attempt the rescue with a battery
loco or something else with compatible braking equipment.

Where would the nearest battery loco be at that time of day, and
would there be anything between it and the train needing to be
rescued (for example, some service trains).

Well, the right answer would be for the railgrinder to have a compatible
braking system or a way of adapting it. No brakes is inherently unsafe.

--
Colin Rosenstiel

On 18/8/10 20:43, in article DJWao.43180$Dt3.31586@hurricane,
" wrote:

On 18/08/2010 12:13, Roland Perry wrote:
In message
, at
03:20:43 on Wed, 18 Aug 2010, martin remarked:
Something that I don't think had previously been released:
The crew of the grinding unit, who had no means of re-applying the
brake, jumped off the unit as it passed through Highgate station.

The "jumping off" was known, but not the bit about the brake.

I heard that it was at Archway.

If I've understood it correctly, the failure occurred at, or near, Archway.
It was decided to haul the failed train North to East Finchley; presumably
they intended to either reverse it down one of the centre tracks into one of
the sidings, where it could receive attention, or possibly just dump it on
one of the centre tracks, where it would at least be out of the way, and
could be collected later. Somewhere North of Highgate station, but before
reaching East Finchley, the coupler failed and the train, having no
functioning brake, ran away Southbound, towards Highgate. When it reached
Highgate station, where it would presumably have been travelling fairly
slowly since it had only run away a short distance at that point, the crew
who were unable to control the train, jumped out, and the train continued to
run South until it reached Warren Street.

We now seem to know pretty much what happened, but we don't know why it
happened. We don't know why the failed train was being hauled North with no
functioning brake of any type, not even a handbrake it seems. We don't know
why the crew couldn't apply the handbrake, we don't know if the braking
systems on the two trains were compatible, and if so to what extent. We
don't know if a MR pipe connection could have been made between the trains,
which would probably have allowed the brake on the failed train to be
applied locally from the cab of that train. If there was no alternative to
isolating the brake on the failed train we don't know why another train, or
locomotive, with a functioning brake wasn't coupled behind it. It's not
possible to see on the small picture of the train what brake connections, if
any, are available. Does anybody know if this train can run under its own
power to a worksite, or if it has to be hauled there, and can only move
slowly under its own power while actually working?

A somebody else said, well done the control room staff for quick thinking,
and keeping all of the other trains out of its way.

In message , at 01:07:31 on Thu, 19
Aug 2010, Stephen Furley remarked:

If there was no alternative to isolating the brake on the failed train
we don't know why another train, or locomotive, with a functioning
brake wasn't coupled behind it.

This seems to be the easiest to answer ... where would you find a
locomotive from, and how long would it take to get to the site with (as
appears to be the case) service trains in the way. The other possibility
would be to take the nearest train out of service, and use that -
although the decision was apparently made to pull using a train from the
north rather than push with one from the south.
--
Roland Perry

In message d7Yao.46398$ag5.13389@hurricane, at 22:19:05 on Wed, 18 Aug
2010, " remarked:

What about the parking brake, if at least to bleed off momentum?

Not an option it seems, unless the RAIB have forgotten about it. Which
seems a tad unlikely.
--
Roland Perry

In article ,
wrote:
Well, the right answer would be for the railgrinder to have a compatible
braking system or a way of adapting it. No brakes is inherently unsafe.

Or to have crew in position to re-enable a disabled braking system
while the train is in motion.

--
Mike Bristow

In article ,
(Stephen Furley) wrote:

Does anybody know if this train can run under its own power to a
worksite, or if it has to be hauled there, and can only move slowly
under its own power while actually working?

We know that it failed because they couldn't start the diesel engine to
move it away from the worksite, don't we?

--
Colin Rosenstiel

In article , (Roland
Perry) wrote:

In message , at 01:07:31 on
Thu, 19 Aug 2010, Stephen Furley remarked:

If there was no alternative to isolating the brake on the failed train
we don't know why another train, or locomotive, with a functioning
brake wasn't coupled behind it.

This seems to be the easiest to answer ... where would you find a
locomotive from, and how long would it take to get to the site with
(as appears to be the case) service trains in the way. The other
possibility would be to take the nearest train out of service, and
use that - although the decision was apparently made to pull using
a train from the north rather than push with one from the south.

Wouldn't there be a battery loco at Highgate Woods?

--
Colin Rosenstiel