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?