Fast / Slow Line Layout

On 18 Jul, 14:02, Graeme Wall <R...@greywall.demon.co.uk> wrote:
> In message <c0acb287-dd74-4e14-baad-3ffd268bf...@f40g2000pri.************..com>
>           MIG <googles...@doreenbird.co.uk> wrote:
>
>
>
>
>
> > On 18 Jul, 12:44, Graeme Wall <R...@greywall.demon.co.uk> wrote:
> > > In message <84a3ac49-ad62-4dc6-9ea6-95446e022...@t12g2000prg.************.com>
> > >           MIG <googles...@doreenbird.co.uk> wrote:
>
> > > > On 18 Jul, 10:46, Graeme Wall <R...@greywall.demon.co.uk> wrote:
> > > > > In message <41n084p1hgiqoujs8kgmbd5qc35e5m2...@********>
> > > > >           David Hansen <SENDdavidNOhS...@spidacom.co.uk> wrote:
>
> > > > > > On Thu, 17 Jul 2008 22:07:05 GMT someone who may be Chris  Tolley
> > > > > > <cj...@supanet.com> wrote this:-
>
> > > > > > >That wasn't always so, though, was it - some termini had arrival sides
> > > > > > >and departure sides.
>
> > > > > > I imagine most did. Firstly an arrival platform and a departure
> > > > > > platform, which was then repeated in larger form with subsequent
> > > > > > rebuilding. Of course in those days trains had/needed a fair amount
> > > > > > of attention and it was also useful to release the locomotive ASAP.
> > > > > > This led to the typical arrangement of an arrival side, departure
> > > > > > side, empty stock lines and locomotive/carriage facilities in
> > > > > > cheaper locations to the station itself. This was only changed from
> > > > > > the 1960s onwards.
>
> > > > > > >I also half-recall reading something about station layouts that asserted
> > > > > > >that the terminus layout with the greatest throughput would be such an
> > > > > > > arrangement with a reversing siding (or loop, though that would turn
> > > > > > > the trains) beyond the arrival and departure platforms.
>
> > > > > > Such a loop was proposed in a number of instances from about 100
> > > > > > years ago, particularly in London. I have vague recollections of
> > > > > > Euston and Waterloo, but may well be wrong. One was built on one of
> > > > > > the tube lines, I forget which (Charing Cross perhaps), but later
> > > > > > abandoned as part of an extension.
>
> > > > > The Piccadilly Heathrow extension involves a loop.
>
> > > > > IIRC the Central Line had a loop at White City.
>
> > > > It did once upon a time.
>
> > > > The current loop referred to is at Kennington on the Northern line
> > > > (from the Charing Cross direction).
>
> > > Can't find a reference to one at Kennington but David is correct about there
> > > being one at Charing Cross, it opened 6th April 1914 and continued in use
> > > until the opening of the extension to Kennington in 1926.
>
> > Yes, and I think it went under the Thames for part of its length.  
>
> It did, roughly between Cleopatra's needle and Charing Cross pier.
>
> > The
> > Bakerloo must have already crossed the Thames, so that section must
> > have been quite crowded with crossing tunnels.
>
> > I wonder if avoiding the loop has anything to do with why the Northern
> > Line platforms are above each other at Embankment and the Bakerloo
> > platforms are above each other at Waterloo?
>
> '60 Years Of The Northern' is silent on the subject.


Clive's answer is eloquent, however. I guess I should have said "at
different heights". It's difficult to judge the horizontal
relationship when you can only see one at a time ...

I had been assuming that the tunnels crossed the loop, but I didn't
realise that it had been filled in and tunnelled through again.

"Clive D. W. Feather" <clive@on-the-train.demon.co.uk> wrote in message
news:zbhweDqX4IgIFwcF@romana.davros.org...
> In article
> <8081db85-a836-43ca-afc5-a584d9640671@k30g2000hse.************.com>,
> rob499@************ writes
>>What nobody has pointed out yet is that when a main line is built as a
>>2-track railway and then widened to a 4-track (as happened on the
>>Great Western, for example), pairing by use is much easier than
>>pairing by direction.
>
> Actually I've already pointed out that it depends on whether you widen on
> one side or on both.

And it's a reasonable assumption that widening on one side is less
disruptive to the existing traffic, and therefore cheaper. Not that that's
an argument for doing it, of course. It's no co-incidence that the LSW and
GN routes operate much more effectively in 4-track mode than, say, the GW or
LNW.

Regards

Jonathan

On 19 Jul, 15:05, "Paul Scott" <notvalidpmsc...@***************> wrote:
> IIRC the inner pair, the fasts, are bidirectional, so the LH or RH pair can
> be used, and apparently the gap between the inner pair is wider than
> historically provided,  enough to allow decent speeds on the pair in use.
> But the platforms then don't allow for stops in both directions of course,
> being only on the outer tracks.

Excellent point - hadn't thought of that; it would be another
advantage of island platforms between the fast and slows I guess.
You'd have to have all manner of nasty rarely used crossovers in place
to sort that out. I'd imagine in the old days if they wanted to keep a
station like that open they might just knock together a temporary
wooden platform and place it over the out-of use lines. Quick
makeshift solutions are a lot easier when the H&SE aren't involved. :)