The possible options for rectifying the tunnels have been, successively,

2001 - Anything (except grouting),
Sept 2003 - "Reprofiling and filling" or alternatively perhaps "let it settle naturally"
2004 - Anything (including grouting).

The Investigation stage has ended.

The Choosing an Option stage is about to start. It'll take till until at least April 2006 to decide.

After that come the repairs, "in the longer term"