On Jul 15, 2:12 pm, MIG wrote:


gurgled happily, sounding much like they were
saying:
even practical. Also Thameslink has some steep sections (eg city
thameslink to blackfriars) and I'm wondering if 200hp would be enough to
propel a 140 ton unit up them.

to snow or something. I've already bored everyone with my anecdote of
a 319 failing twice to get up the slope in snowy conditions before
reversing to the north end of City Thameslink and finally making it
with long runup.


Todays Thamelink operations - and all those of the greater operation
post 2015 - seem to work OK without any resort to self propulsion.
There are no significant engineering blocks where diesel working would
be useful - lines tend to be closed outright rather than OLE
isolations, and the SR zone tend not to indulge in traction only
isolations.

It is the central sections BF-City-KX that would be most vulnerable to
a train failure. But the service will be so intense through there that
rather than **** around with alternative power (that will be so
infrequently used it will itself be a liability) you simply bring up
the train behind and push out.

And as others have quite rightly pointed out, the central section has
some fierce grades - that from City to BF is the steepest on the
network for practical purposes (although ?? might change with the
upgrade ??). Bearing in mind that an EMU with more than 50% motors cut
out will struggle up there, I don't see how piddly 200 hp power packs
will help any.

Since the new TL is supposed to be about longer trains, the chances of
a train with more than 50% out reduces - because to get to that state
with modules of 4car EMUs you need multiple motor failures across the
train affecting more than one unit. Thats pretty rare. Even with a
complete disablement of a whole train, you push out with a fully
functioning train, so unless a farce arises where it just happens that
it is a 4car following a failed 12car, probability suggests its a fair
risk to not bother with alternatives.

I have to wonder if the person who wrote this into the spec just
happens to be a TL commuter and got caught one day in one of those
rare events of an AC/DC changeover failure at Farringdon and has gone
for sledge hammers to crack nuts approach. Those failures are very
rare, I've never been involved in one in regular travel on the route
ever since it opened.

On top of all this, won't these days of H&S paranoia demand extraction
and filtration equipment in the tunnels to remove noxious gases from
diesel engines, bionic duckweed trurbines or Swordfish power packs ?

--
Nick