In message , Peter Masson
wrote:
The problem is that, as a 'one engine in steam' branch, it is limited
to a train every 45 minutes. A loop built to heavy rail standards would
be too expensive.

[Catching up]

Why? You've just got to reinstate the one that used to be there. You
could even use self-restoring points like on RETB lines.

Hmm, if you put in a loop then you need signalling instead of running
OEIS. That's probably the major cost.

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"Clive D. W. Feather" wrote in message
...
In message , Peter Masson
wrote:
The problem is that, as a 'one engine in steam' branch, it is limited to a
train every 45 minutes. A loop built to heavy rail standards would be too
expensive.

[Catching up]

Why? You've just got to reinstate the one that used to be there. You could
even use self-restoring points like on RETB lines.

Hmm, if you put in a loop then you need signalling instead of running
OEIS. That's probably the major cost.

Plus, if you restore the loop that used to be there you presumably also have
to restore the platform that's now disused. And to do that, you presumably
have to make it fully accessible. With tram operation there may be room to
have a layout like that at the restored loop at Penryn or the new one at
Dyfi Junction, or, if a 2-platform solution is needed, tram operation
permits a new foot crossing, while heavy rail would require an accessible
footbridge.

Peter

On May 22, 5:14*pm, "Peter Masson" wrote:
"Clive D. W. Feather" wrote in ... In message , Peter Masson
wrote:
The problem is that, as a 'one engine in steam' branch, it is limited to a
train every 45 minutes. A loop built to heavy rail standards would be too
expensive.

[Catching up]

Why? You've just got to reinstate the one that used to be there. You could
even use self-restoring points like on RETB lines.

Hmm, if you put in a loop then you need signalling instead of running
OEIS. That's probably the major cost.

Plus, if you restore the loop that used to be there you presumably also have
to restore the platform that's now disused. And to do that, you presumably
have to make it fully accessible. With tram operation there may be room to
have a layout like that at the restored loop at Penryn or the new one at
Dyfi Junction, or, if a 2-platform solution is needed, tram operation
permits a new foot crossing, while heavy rail would require an accessible
footbridge.

Peter

I still don't accept the signalling argument. Given a simple layout
with a single loop in the middle, both single line sections can be
protected by simple virtue of the onward section of line being in use
unless the other train is in the loop opposite. That can't be
expensive, surely. Even if you decided you needed some signals, all
you'd need are a pair of colour signals, and they'd only have to pick
up the trains in the loop, and be set to danger otherwise. It all gets
much more complex if you ever added a 3rd train of course, but that's
not where things were going, so I'll sidestep it.

Stock however, I do accept as a problem. Such is the issue of the
modern railway's fixed formations. Silverlink used to get by operating
a metro unit on the line at times...and I can't help but wonder if
transferring the branch to LO and letting them operate it with a 378
might not work out better, (even more so if they'd link it to the DC
lines )

....and I agree about the footbridge. Do you know offhand how much the
modular stuff as found at Mitcham Eastfields would cost in this
context versus the costs of the more complex track arrangements for
single platform operation?