Transport for London (TfL) has announced plans to begin modernisation work on 40% of London's Tube network.

In a statement, the body said work will begin later this year on updating the signalling and train control systems on the Circle, District, Metropolitan and Hammersmith & City lines. 

The body said the work, will increase the frequency of trains during peak periods to 32 per hour in central London. That's a train every two minutes. 

However, it added that upgrade work on the overcrowded Piccadilly, Central, Bakerloo and Waterloo & City lines won't begin until this round of upgrades has been delivered, expected to be by 2022. 

The announcement comes off the back of completed modernisation plans on the Victoria Line, where 34 trains run per hour, as well as the Jubilee Line, which has 30 trains per hour. Work's just begun on the Northern Line, which TfL reckons will eventually increase capacity to allow space for 12,500 passengers per hour. 

The £5.4bn contract for the upgrade has been awarded to French transport contractor Thales, which includes the cost of 191 air-conditioned, walkthrough trains.

The investment will also include new track, longer platforms and rebuilt, high-tech train depots with "advanced technology to ensure the highest levels of train reliability", TfL said. 

Nick Brown, London Underground's managing director, said the move will "transform the journeys of millions of our customers, significantly increasing service and reliability and frequently".

source: CityAM