With a larger new fleet expected soon, there is a need for more stabling on the line. The idea is to provide more on the Uxbridge branch for morning service start-up, reducing pressure on reversing of trains from Northfields depot at Acton Town. This will become more crucial when eventual resignalling permits more intense service, and simplified track layouts are possible.
Presumably the rationale for changes at the South Harrow Sidings is to provide extra overnight stabling for trains. As all trains are likely to be identical (at least to start with) and given the usual budget pressure to avoid unneccessary expense I would thought the cheapest answer would be to simply extend the existing 6 sidings so they can store two trains on each siding rather than just the current one train per siding.
The initial phase is to provide additional stabling capacity which will allow the partial closures of Northfields and then Cockfosters depots in turn.
The gap between the sidings and eastbound track will be narrowed, so the the first two new sidings will be within the footprint of the existing first.
This work just goes over the boundary into designated Metropolitan Open Land.
A second phase at South Harrow could potentially double each road to two trains and provide an access route from Wood End Road which is not part of phase 1.
Are the proposed depot closures for rebuilding for new stock accommodation?