On 2008-11-08 15:35:26 +0000, D7666 said:

On Nov 8, 2:33 pm, Robert wrote:


It's a bit more complicated than that. I think that you will find that
the Stammstrecke is defined as the section from Pasing to
Munich-Ostbahnhof, a distance of marginally over 7 miles; it is not
just the central tunnel section.

Where did I say it was the tunnel section ?

I never used the word tunnel. I said core ... and I know Stamssstrecke
is Pasing - Ost.

However, I did err in that the two track section is as you say Ost -
Donnerburgerbrucke. I had the latter station in my minds eye.

What was confusing me was that you wrote

Nowhere on the Mch S-bahn stammstrecke (the core section) are there
junctions of any sort on the twin track core - only at the ends.

My argument was that the Stammstrecke is 2 track all the way from
Pasing to the Ostbahnhof (we agree) but in that length it /does/ have
two grade separated junctions, at Laim and Donnersbergerbrücke. There
is also the junction at Ostbahnhof where lines S5 and S6 reverse. We
also agree that both Pasing and the Ostbahnhof have 4 dedicated
platforms to be able to launch and accept trains at the required
frequency.

Agreed that Donnersbergerbrücke has 4 platforms but 2 of them are used
by the BOB trains that tunnel in from the south, stop at the station
and then fly over the S-Bahn tracks to get access to the surface level
Hbf. The S7 S-Bahn trains to and from the tunnel section use the BOB
lines from the south, the BOB platforms and join and leave the
Stammstrecke at the east end of the platforms.

However arcane the details, the point is that a 28/30 tph service can
be operated on a two track route with junctions if the system as a
whole is well designed. For example note that where trains /join/ the
Stammstrecke they do so at stations which have island platforms so
station work on trains from different routes can be overlapped so as
little time is lost as possible. Apart from the possible savings in
capital cost I can't understand why at least the /southbound/ platform
at St. Pancras Low Level was not built as an island. Why design into a
system which uses very expensive infrastructure a bottleneck which
prevents it being used as intensively as possible? In the long term it
is a waste of resources, both of the passengers' time (by offering a
less frequent service than could be done) and money.

signals upgrade is
to LZB ... Seltrac S40 is an LZB ...
Then there is hope for us yet!

There had better be ... ;o)


--
Robert