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London Bridge resignalling for Thameslink 2000 will have to wait on technology
This column tends to cover subjects you won't read about anywhere else. There are several reasons for this.
Informed Sources is a personal column and at times reflects my particular interests. It also has a mission to demystify techie stuff for the lay reader. But above all the aim each month is to explain what is going to happen and why, so that when a big story breaks readers are not surprised.
Take the related subjects of safety cases, acceptance and computer Based Interlockings which have featured on and off for a long time now. This arcane area is now determining the Strategic Rail Authority's approach to Thameslink 2000.
As you will recall the Transport & Works Act Inquiry into the project identified ‘ serious shortcomings' in the case of the proposals for London Bridge Station. The Inspector was thus unable to recommend either compulsory purchase of some necessary land, or the approval of the request for planning permission.
Where does CBI come into this? Well SRA Chairman Richard Bowker has written to the Transport & Works Act Processing Unit explaining that whatever happens with the T&WA powers, Thameslink 2000 will now be a two phase project.
This letter summarised a joint review of the project carried by SRA and Railtrack, following the Inspector's report. This revealed that signalling technology considered essential for the implementation of Thameslink 2000 has ‘taken longer than expected to develop'. Well, you all knew that.
Back in August 2000 what was then Adtranz Signal was selected for resignalling Thameslink 2000, including London Bridge , with the Ebilock CBI.
Apart from three or four CBIs doing the work of a dozen Solid State Interlockings, the more recent technology had a number of other advantages. For example, it could overlaid on the existing signalling as track layouts were remodelled since Ebilock comes with computerised design facilities which enable track layout changes to be accommodated quickly.
There was also a cunning plan for commissioning. Ebilock would be linked to existing lineside signalling equipment through changeover boxes. During night time possessions you could switch from the existing interlockings to Ebilock for testing and commissioning, and then switch back again for the morning service.
Delays to the Ebilock pilot signalling scheme at Horsham, plus similar slippage with the Ansaldo and Siemens CBIs, meant that the Ebilock proposal was quietly dropped.
And in his letter Richard Bowker says that CBI will not now be ‘sufficiently developed for use on a project of this scale' until ‘about' 2006 or 2007. Without CBI, resignalling the tracks through London Bridge and to the east of the station would require possessions ‘of up to six months at a time'.
My signalling chums think this estimate is OTT. After all, completely resignalling and remodelling Crewe was done in a six week possession. Depending on how far east the work goes, three months ought to be sufficient.
Anyway, a six month closure would be ‘hugely disruptive' and ‘unacceptable' to the travelling public, so the SRA is proposing deferring remodelling and resignalling until CBI is ‘proven and available'.
But the SRA believes that the St Pancras-Blackfriars-London Bridge ‘core section' of Thameslink 2000 can be remodelled and resignalled to handle up to 24 trains/hour using what it calls ‘conventional signalling technology' and we know as SSI. Network Rail is currently discussing this project with Alstom.
As a result of all this, the SRA and Network Rail now propose a two stage approach. Cynics may note that this would also defer some of the expenditure to the end of the 10 year transport plan or beyond.
Of course Thameslink 2000 is not an island. It will be needed to disperse passengers arriving at St Pancras International when the Channel Tunnel Rail Link opens in 2007.
This makes T&WA approval for Phase 1 a matter of urgency. Given an early go ahead, the upgrading works on the core section, would be completed by 2007. In parallel, platforms at outer stations would be lengthened to take 12 car trains.
In fact, there will be a six month blockade of existing Thameslink services during the second half of 2004 when the new station box is built for St Pancras Midland Road station – and what a wonderfully retro station name that is.
This blockade provided the ideal opportunity to carry out preparatory work for the major changes at Blackfriars and the extension of Farringdon station associated with Thameslink 2000. Both schemes were scheduled for after the blockade.
If Phase 1 doesn't go ahead, signalling and track work would have to be based on the assumption that the route would reopen unchanged. This, says SRA, would put back Thameslink 2000 by a further year and increase the cost by £100m.
So, max pressure on Deputy Prime Minister John Prescott, who is responsible for the T&WA unit, to give the go ahead for Phase 1. It will require the demolition of modern buildings at the western end of London Bridge station and the cutting back of the existing adjacent station concourse roof. Buildings in Queen Victoria street and the Borough High Street conservation area would also have to be demolished.
Allowing these demolitions to go ahead so that Phase 1 can start, says the SRA, would not prejudice future applications concerning listed buildings which would be demolished under Phase 2. Over to you JP.