A large sinkhole, 15 metres deep and two metres wide, has opened up beneath rail lines at Forest Hill. Needless to say, this section of track is going to be closed for some time, while checks are made and the hole is filled.
The unexpected void is bad news for commuters, already struggling with a reduced service on SouthernRail lines. As of now, trains are running to all kinds of exotic diversions, as tabulated here:
The hole is also affecting Overground services. No trains are running between New Cross Gate and Crystal Palace/West Croydon.
We'll update this story as more information is released.