"Tom Anderson" wrote in message
...
Am i right in thinking that it's normal double track downward from Barnes
in the direction of Richmond and Reading? And thus that Barnes looks like:

to Hounslow
\ \---------
\ ###
\--------- to
--------------- Clapham Junction
###
---------------
to Richmond

More Like . .

Hounslow
~BARNES~
\ \
\ \ ##1##
\ *---*----------*----- Slow
\ / \ \ UP
X --*----------*--- Fast
/ \ / ##2##
---*---+-- Clapham Junction
\ ##3##
---*-----*-*------------*--- Fast
\ \ / DOWN
--------*--------*----- Slow
##4##
Richmond


Doesn't that mean that local services via Richmond have to share with
mainline services to Reading? Doesn't that suck? Or is the Reading service
not a 'real' main line?

The Reading Fasts usually run on the Down Slow and can thus overtake
stoppers going to Richmond or Hounslow, and additionally are able to
traverse Barnes Junction in parallel with the Hounslows without conflict.
Not sure which line UP Fast trains use habitually, but the Slow could be
used if a parallel movement is coming off the Houslow line.

The timetable is a compromise. On the shared sections west of Barnes, the
Stopping trains have to precede the Fasts by a margin equal to the normal
platfrom reoccupation time plus the difference in running time between the
shared sections extremites, perhaps the Stopper turning off at Twickenham or
Staines. The difference in running time is the limiting factor on capacity
as it effectively freezes out regular parts of the hour that could be used
by a more frequent all stopping service. A common problem with this type of
service mix is late presentation of a longer distance Fast train at a
junction merging with shorter distance Stopping trains. The Stopper is less
likely to be delayed on its shorter simpler network, but may be held a
minute or 2 due to priority rules. Anything more and it must go or else the
local services could start to decay. Now the Fast has to follow it in until
the next passing point or diverge.

Some Fasts run via the Hounslow loop in the peaks, and for the brief period
when there were 4 trains an hour all day to and from Reading, 2 of those ran
via Hounslow with some stops in place of Twickenham and Richmond.

--
Mark