bob wrote:
Recliner wrote:
wrote:
On Fri, 02 Sep 2016 13:46:50 +0100
Recliner wrote:
I must admit I don't understand why Crossrail and the North Kent line
have separate island platforms, rather than having the Crossrail pair
between the third rail tracks, thus allowing cross-platform
interchanges. The down third rail track could have been re-routed to
the north of the portal, so that it was on the north, rather than the
south of the new Crossrail pair. With that arrangement, both down
tracks would flank one island platform, and both up platforms the
other. It would save a lot of passengers the hassle of having to cross
from island platform to the other.

Presumably that would require the crossrail tracks to cross the 3rd rail ones
complicating signalling, power supply isolation and causing potential hold
ups on both lines due to a problem on the other.

No it wouldn't. The Crossrail portal would be between the up and
(slewed-north) down third rail tracks. The Crossrail tracks would stay
between the third-rail tracks until the former's buffer stops at Abbey
Wood. Beyond Abbey Wood, the two third-rail tracks would come together
again and resume their former alignment towards Dartford. It would be a bit
like how the diesel track pops up between the two Central line tracks at
Greenford.

It's a while since I've been down that way. What is the Crossrail alignment
between Woolwich and Abbey Wood? For Crossrail to run between the 3rd rail
lines requires the Crossrail route to pass under a realigned down 3rd rail
line at some point, or if the Crossrail lines were run as the outer pair,
the westbound Crossrail line would need to pass under both 3rd rail lines.
Incidentally, how are the Crossrail lines named in terms of "up" and
"down"?

Yes, I queried why the down third-rail track wasn't moved to the north side
of the new portal. The third-rail tracks were moved slightly to the south
anyway, and I'd originally thought that the final alignment would have seen
the down line realigned to the north of the new portal (it would have had
to have been left to the south of the portal during the construction phase,
but the new down third-rail track could have been built to the north, once
the Crossrail construction was complete).