To clarify some matters:
All of the D78 Rail Adhesion Trains (RATs) are based at Neasden depot. Generally they live at the very back and can (just) be glimpsed from a passing train - southbound gives the best opportunity. From time to time they are shunted onto the Klondike roads, those between the depot and the running lines. There is a history of trains getting tagged by graffiti artists when left here for too long.
The D78 RATs are due to be CBTC fitted but this is not a requirement for this year. The trains will not run south of Neasden, and no further CBTC migration is planned for this year. It should also not be an issue next year with focus switching to the District for the next few sections.
The current priority is to get CBTC fitted and working to the bulk of the engineers’ fleet, for which a shutdown took place this weekend just gone. There were significant issues with this (I’ve been off so I don’t know how the weekend went) and the resulting requirement to run only via Ealing Common causes significant delays for some engineering possessions.
Once Sandite season commences one of the 5-car units will be out several times daily.