Charles Ellson wrote:
On Fri, 2 Sep 2016 16:56:35 -0000 (UTC), 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.

Popping up tends to require a bit more excavation.

The line pops up anyway. It emerges from the tunnel portal. All I'm
suggesting was that the portal could have between the North Kent tracks,
rather than immediately to the north of them.

That costs more
money and might in some places be undesirable anyway if only for the
need to ensure support for what is being burrowed under.

It wouldn't have cost significantly more to build, and wouldn't require any
special support.


It's probably a bit late now anyway.

For sure, I'm not suggesting that it be changed now, just questioning why
it was done the way it was.