Regular users of the Met will have seen the posters saying that the line
would close early each night south of Wembley Park, Mon-Wed.

From
https://tfl.gov.uk/info-for/media/pr...e-start-16-may

Quote:

The condition of the track and drainage between Baker Street and Finchley
Road is very poor. It is prone to flooding after periods of heavy rain and
is a regular cause of signal failures, which delays customers.

To help resolve the problem, engineers will replace 6.4km of track and
drainage systems between Baker Street and Finchley Road.

LU has chosen to extend its normal evening engineering hours so the work
can be completed in around two years. The alternative would have involved
either a full closure of this section of the line for almost six months or
a very large number of weekend closures over seven years.

The extended engineering hours will mean that on Monday to Wednesday
evenings the Metropolitan line will close earlier than usual, at around
10pm between Aldgate and Wembley Park. Some very early morning trains on
Tuesdays to Thursdays will also be affected. A very small number of weekend
closures will also take place to allow work to progress at a faster rate.
…

_____


For anyone wondering what would be happening on those nights, here's the
engineering story. It turns out that they're replacing elderly bullhead
rail and wooden sleepers with modern slab track, poured in situ, 10.5
metres a night:

http://www.railengineer.uk/2016/12/1...-cast-in-situ/