Every activity on the Broadgate raft project is governed by the 80 page possessions schedule, worked out well in advance and almost impossible to amend. A possession begins when the PICOP - Railtrack's person in charge of the project - issues a Form B authorising overhead line contractor GTRM to shut down the power on a particular section of track.
GTRM then passes a Form C to the other contractors' PICOWS - persons in charge of the works. The rail lines cannot start operating again until the PICOWs return the Form Cs to GTRM and GTRM reconnects the power and returns Form B to the PICOP. Failure to recover the Form Cs - even if the PICOW has wandered off home at the end of his shift with the form in his back pocket - means trains will be stuck. And this would be a 'very serious, very expensive matter'.
So far this has never happened, and nor will it, says the project team.