Economy of London project is construction of 42 km (26 mi) of new tunnels connecting stations in central London including a branch to Canary Wharf in east London. It is Europe's biggest construction project with a £15 billion projected cost. An additional line, Crossrail 2, has been proposed. London is served by six international airports which are the world's busiest city airport system by passenger traffic. These are Heathrow, Gatwick, Stansted, Luton, London City, and Southend. There are a number of proposals for expanding airport capacity for London including expansion of London Heathrow Airport and expansion of Gatwick Airport. The principal argument in
Khanbumbat Airport the property employing approximately 200 people, and Oyu Tolgoi was the "biggest mining exploration project in the world." In January 2013 Oyu Tolgoi started producing concentrate from the mine. The old building of the airport was built in 2000-s. In 2004 the airport was called "Oyut Airport". The runway was dirt. In 2007 it started accepting passenger flights. The new airport was built in 2012. It opened on 10 February 2013. The Khanbumbat Airport and Oyu Tolgoi mine is in the South Gobi Desert of Mongolia, north of Mongolia's border with the People's Republic of China, where the mined copper