LONDON, June 15 (Xinhua) -- Siemens has won a 2-billion-U.S.-dollar contract to design and manufacture 94 new trains for London Underground's busy Piccadilly line, it was announced Friday.

More than 700,000 passengers a day, particularly commuters and tourists, use the Piccadilly line, which runs between Cockfosters in suburban north London and Action Town in the west.

However, Transport for London (TfL) said the combination of limited fleet size and old signalling technology has restricted its ability to increase capacity across the line for many decades.

The new train order, the first under TfL's Deep Tube Upgrade Program, will mean the replacement of the entire 1970s Piccadilly line fleet.

The existing Piccadilly line trains were introduced in 1975 and are now one of the oldest train fleets in passenger service in Britain.

The line, now 71 kilometers in length, first opened in 1906 and serves key tourist areas such as Piccadilly Circus, Leicester Square and Covent Garden as well as London Heathrow Airport.

London Transport commissioner Mike Brown said: "Today's announcement of our intention to award the contract to design and build a new generation Tube train is a huge milestone for London Underground.

"We are delivering the biggest investment programme in our history to continue to improve customers' journeys and support London's population and employment growth."

The investment will help support London's growing population which is set to increase to 10.8 million by 2041, supporting new jobs, homes and growth in the British capital, added TfL.

The award of the contract will pave the way for Siemens Mobility Limited to progress its plan to build a new factory in East Yorkshire, to manufacture and commission trains.

The factory would employ up to 700 people in skilled engineering and manufacturing roles, plus up to an additional 250 people during the construction phase of the factory.

From 2023, new 94 new state-of-the-art Inspiro trains will be delivered on the Piccadilly line enabling up to 27 trains an hour to operate at peak times by the end of 2026, meaning a train every 135 seconds at the busiest times.

Combined with a signalling upgrade and the purchase of additional trains, peak period capacity on the busiest central sections of the Piccadilly line will increase by more than half by the end of the 2020s and will mean an additional 21,000 customers will be able to board trains every hour during peak times.

Sabrina Soussan, CEO of Siemens Mobility, added: "Our metro trains travel the equivalent of 60 times around the world each week, transporting millions of passengers comfortably and efficiently."

The four Deep Tube lines make up a third of the London Underground network, carrying around 2 million passengers a day on key corridors linking the City, the West End, King's Cross and Heathrow Airport.