NETWORK Rail has begun work on a £326 million 18-month project to upgrade the North London Line in time for the 2012 Olympic and Paralympic Games.

The long awaited scheme, made possible by cash from the 2012 budget, will double passenger capacity to support up to eight services an hour each way. It will also involve extending platform lengths on the London Overground route in readiness for a new fleet of 32 air-conditioned trains later this year.

As part of the project more than 200 signals will be upgraded, four miles of track and 69 switches renewed, 30 platforms lengthened and seven more stations improved.

Transport for London’s programme of station improvements – including lighting and passenger information screen upgrades and lift installation – will continue in tandem with the line’s upgrade.

A £108 million contract for civil engineering work on the line is shortly to be awarded by Network Rail to one of four short-listed contractors – Carillion, Balfour Beatty, Colas, and a Fitzpatrick/Grant Rail joint venture.

The project is being funded by a £166 million injection from TfL, topped up with an £82 million grant from the Olympic Delivery Authority, to improve public transport connections to the main Olympic site in Stratford, east London.

Network Rail is contributing £75 million to the scheme, with a final £3 million from the Department for Transport.

In addition, the DfT has allocated a further £354 million to increase the line’s freight capacity by four-tracking sections of double track between Dalston Junction and Camden Road, but this is unlikely to be completed in time for 2012.

Platforms will be extended at Kentish Town West, Camden Road, Dalston Kingsland, Homerton, Crouch Hill, Leyton-Midland Road, South Acton, Acton Central, Willes-den Junction High Level, Kensal Rise, Brondesbury Park, Brondesbury, West Hampstead, Finchley Road and Frognall, Hampstead Heath, Caledonian Road, Canonbury and Highbury and Islington.