"Tom Anderson" wrote in message
rth.li...
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!

Why assume it even has a conventional railway air brake system. We're
talking about a large item of yellow plant brought in to the system that is
designed to work independently?

Reports earlier that it was an 'engineering train' and pictures of normal LU
battery locos aren't necessarily helping as far as I can see. It's just as
possible that it has never been designed to form part of a 'train' as
everyone is assuming...

Paul S