Richard J. wrote:
I've no doubt the junction itself is in rather poor shape, which is why
it's to be relaid. The plain line stretches to Bollo Lane and Acton
Lane Junction could easily be relaid in weekend possessions.

Indeed. I'm not suggesting that the reason for the blockade is to
permit this to be done - I'm merely pointing out what the conditions
are at the site.

There were drainage problems at Victoria at the start
of the District Line relaying works, which necessitated an extra weekend
closure. And the lack of space under the overbridge is not exactly a
rare occurrence (e.g. District Line tunnels). What I'm struggling to
understand is why it's really necessary to suspend the heavily-loaded
peak Richmond line services for a whole week. Or is it just Network
Rail deciding it's more convenient for them to mount a blockade, and sod
the passengers?

That may very well be the case. Personally I don't quite understand why
they need nine contiguous days to do it - four I could understand,
seven would be a stretch, but nine?