When Deputy Prime Minister John Prescott bought the first ticket to ride the new Jubilee Line Extension from Stratford to North Greenwich on 14 May, there was much celebration. And rightly so. At the time, the project was 14 months late, £1.3bn over budget but at least the trains were running - and running very well.
But as far as JLE commissioning manager David Waboso is concerned, the big technical celebration came last week - namely getting the railway's signalling system ready and approved to run 'real' services to central London. He says gaining the Railway Inspectorate's stamp of approval on the new control system was vital as the task sat right in the middle of the JLE's critical path to opening this year.
'JLE has been looked at as a massive civil engineering project with big tunnels and big machines,' says Waboso. 'It is, but ultimately the real risks on a railway project are not in the civil engineering but on the systems that get the trains running.'
What Waboso is so pleased about is successfully switching control of the trains from a tiny temporary control tower at the Stratford depot to the purpose built centre in west London.
HMRI approval means that not only can the existing four stations on the JLE be run from this new central facility, but also that it is clear to operate trains to the remaining stations through to Waterloo. Final test running started this week to prove it will be ready in time for the mid-September opening.
So what made this operation so tricky? Waboso explains that the risk came in developing and then proving the sophisticated software used to control all the systems on the new railway. This includes signalling, power supply, radio links, tunnel telephone and emergency power cut-off, closed circuit television, public address system and ventilation systems. Each is highly complex in its own right, but also has to be married together in such a way that the operators can control the trains safely and efficiently.
'Graceful degradation is the key,' says Waboso, who learnt lessons from his seven years' dealing with the Docklands Light Railway's computers. 'We must plan the software so that if one part falls over you have capacity to bring the rest of the systems down slowly and under control.'
This means that if the West London control centre grinds to a halt, trains can still be moved, communications systems can still be operated and safety on the railway can always be guaranteed. It means deciding what you want to do in every scenario and proving how to do it safely.
The key decision to set aside the much lauded, but so far undelivered, moving block signalling system was in fact taken long before the September 1998 appointment of Bechtel to rescue the project. By autumn 1997 it had become clear that the software was not going to deliver the kind of reliability that the JLE demanded.
But Bechtel's decision to introduce train services incrementally in three stages was, from the point of view of risk management, the only way to go. In addition to the valuable feedback from running a partial live service, the decision, coupled with last week's success, now means the JLE is virtually certain to be ready to take travellers to the Dome from central London by the millennium.
Completing the link up with the existing Jubilee Line is, of course, still a theoretical reality. But from an operational point of view, only politicians will see achieving this by the new year as anything but icing on the cake.