On Wed, 31 May 2017 13:45:22 +0100, "tim..."
wrote:

as the bottleneck on the mainline runs all the way back to new Malden, where
are the extra paths on that part going to come from to achieve that?

I think the plan was to add a 5th track from the tunnel portal to at
least New Malden... Perhaps Hampton Court Junction.

Richard.