Crossrail is facing major signal problems which could prevent any trains from being allowed to run when the line's due to open in 2018.
The South-East's £15billion new railway is on course for humiliation as engineers admitted the complex signal issues may not be resolved in the next three years.
A source inside the project claimed it was still likely that Crossrail would open, with reduced services, but suggested said it was also possible that no trains would be running at all in 2018.
|Crossrail Map click to enlarge|
Crossrail will adopt both traditional metro signalling and modern high-tech systems to connect trains on the 26 miles of new tracks underneath London to existing major cross-country rail lines.
As it stands, engineers are struggling to create 'interfaces' - meaning the trains are unable to shift smoothly from the orthodox Metro system to the state of the art system used once outside central London.
Crossrail's chairman, Terry Morgan, conceded that a 'mitigation plan' was being put in place.
The admission confirms the worry that signalling on the 73-mile Berkshire-to-Essex link won't work properly by 2018.
A source who has recently worked on Crossrail told The Independent: 'The most likely scenario is that Crossrail will open with a significantly reduced service.'
A second source said: 'In the extreme you wouldn't be able to run any trains. Signalling technology in this industry is something that has challenged everybody for a very, very long time.'
A huge part of Crossrail equates to a a new underground system, running through busy Tube stations such as Tottenham Court Road and Liverpool Street.
But Network Rail, the government-backed body in charge of the country's most important train tracks, is hoping to introduce a highly complex signalling system across the lines, which will connect with Crossrail.
This will feature technology akin to GPS, providing pinpoint accuracy on the location of a train - so that more than one can stop and start on any single section of the line without the danger of a crash.
The ability to locate the exact position of trains should make it easier to manage and increase the flow of Crossrail trains into London.
Crossrail, Europe's biggest construction project, is initially scheduled to run 24 trains per hour during peak periods, and it is hoped this will increase to 30.
|Above & below. Eastbourne Terrace which runs alongside |
Paddington, has been closed to all traffic except buses,
to allow construction of Crossrail.
The major issue facing Crossrail is to the west of London, once the track passes through Paddington station.
Industry experts suggest the issue was frustrated by Network Rail separately launching its own 'digital railway' programme last year.
This meant introducing advanced technology - such as software that accurately forecasts temperature and rainfall across the UK's major lines.
Crossrail has so far involved more than 10,000 construction workers across 40 sites and up to now encountered few problems.
|Eastbourne Terrace showing the course that the new railway will take|