The work between London Cannon Street and Charlton will mean that buses will replace trains between Lewisham and Charlton and Dartford via Woolwich Arsenal.
Trains will be running on a revised timetable over the weekend between these points, with some stations not being served whilst engineering works take place.
On Saturday, engineering work taking place between Herne Hill and Streatham will close some lines, with no trains running on Sunday.
On Saturday and Sunday, engineering work taking place between Charlton and London Cannon Street will close the line between Charlton and Slade Green.
Stations affected:
This will mean several changes to services over both days:
Saturday
Trains normally running between Luton and Rainham will only run between Plumstead and Rainham and on a revised timetable.
Alternative Travel on Saturday
On Saturday, Thameslink has advised that tickets will be accepted on Southeastern trains running between Plumstead and London Bridge, London Underground services between London Bridge and Canning Town, DLR services between Woolwich Arsenal and Canning Town, and Elizabeth line services between Abbey Wood and Farringdon.
Sunday
On Sunday, trains normally running between Kentish Town and Rainham will run between Dartford and Rainham only and to a revised timetable.
Alternative Travel on Sunday
On Sunday, tickets will be accepted on Southeastern trains between Dartford and London Bridge, London Underground services between London Bridge and Canning Town, DLR services between Woolwich Arsenal and Canning Town, and Elizabeth line services between Abbey Wood and Farringdon.
On Saturday, engineering work taking place between Herne Hill and Streatham will close some lines, with no Thameslink trains running between Herne Hill and Wimbledon or Sutton .
On Saturday, trains will run between Herne Hill and St Albans or Luton, and on Sunday these trains will not run.
Stations affected:
Alternative Travel
Thameslink has advised customers that tickets can be used on London Underground Northern line services between Kings Cross St Pancras and Morden.
Tickets can also be used on London Buses between Blackfriars and Tulse Hill or Streatham, or between Streatham and Sutton (via Wimbledon or via Mitcham).
Tickets to travel between East Croydon and Wimbledon can also be used on London Tram services between these stations over the weekend.