Train passed red signal?

In case you aren't familiar, the in-cab signalling used on the Jubilee line requires the train and signalling system to talk to each other so that the signalling system knowns where the train is and the train knows the limit of it's movement authority.* A non-communicating train is simply one that is not currently talking to the signalling system (there are multiple reason why this might happen). There are defined procedures set out for what drivers and signallers/controllers must do when this happens. I don't know the details of these, but turning the train off and then back on again (what you almost certainly experienced when the lights went off and it all went silent) to completely reset the train's computer is one thing that can be tried to try and get them talking again (although obviously not the first thing).

*In a traditional signalling system, a green signal gives authority to move up the line to the next signal. This signalling system works the same way, except the limits of authority are not marked by signals.


The word you didn't hear was probably "berthed". Each platform has an ideal stopping point, with a small tolerance either side of that (±50cm), so that the train lines up with the platform doors properly, this is termed its berth (I guess the term comes from the space for a ship alongside a dock?). Outside that window the signalling system isn't guaranteed to correctly identify the train as being at the platform and the system that stops the doors being opened on the wrong side of the train also wont recognise that it is at a platform and so wont allow the doors to be opened (I can't remember whether this is part of or separate from the signalling system).* If the train stops short then it can be driven forwards until it's in the right place (this happens not infrequently on the Central line) but if it has gone too far then nearly always the train will have to continue on to the next station (I believe that communication with the line controller or signaller needs to happen before doing so though).** It is also possible for a train to have stopped in the right place but for the system to have not recognised this, I think this would also be spoken of as "not berthed properly" (it would not surprise me if this is what happened to your train at Waterloo). In this situation it's possible that the train might be moved forwards slightly (obviously not if it's right at the forward end of the window) to get the systems to try again, and/or the platform doors can be opened by operating a control panel on the platform.


*This can be overridden if needs be, but obviously there are procedures that must be done first to ensure that there really is a platform there.
**There are alternatives, but as these involve very time-consuming procedures to make sure everything is done safely they're basically never done.

p.s. sorry if you know any of this already.