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Moving block signals finally go ahead on Jubilee Line

ALCATEL WILL install a simplified moving block signalling system on London Underground's Jubilee Line by 2009, 10 years after plans to introduce a similar system were scrapped.

The signalling contractor won the £300M contract to install the system last week.

It will install the signals for TubeLines, the consortium responsible for upgrading the Jubilee, Northern and Piccadilly lines.

Moving block signalling was originally commissioned from supplier Westinghouse for the Jubilee Line Extension, which opened in 1999.

The previously untried Westinghouse system enables the frequency of trains to be increased by allowing trains to travel closer together, and was to have increasing line capacity by 50%. It was to be flexible enough to allow changes to distances between trains depending on their speed.

But the system was abandoned after problems with the inter-train communications system and with communications between trains and the train control centre (NCE 21 May 1998).

There were also problems marrying the Westinghouse system with the existing fixed block system on the rest of the Jubilee Line.

The new signalling system designed by Alcatel was described by a TubeLines spokesman as a 'halfway house' between moving block and traditional signalling.

It uses sophisticated intertrain communications technology to reduce headways, but keeps fixed minimum distances between them.

TubeLines hopes this will enable it to increase line capacity by 20%.

Alcatel's contract also covers installing the system on the Northern Line by 2011. A separate contract for the Piccadilly Line will also be awarded.

Almost identical Alcatel systems are already being used on metros in Vancouver in Canada, Ankara in Turkey, and on London's Docklands Light Railway.

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