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
London City Airport be found. The waiting area is connected to piers on both sides where corridors on the upper floor lead to the departure gates on the ground level. As the airport has no jet bridges, walk-boarding is used on all stands. The following airlines operate regular services to and from London City Airport: Passenger numbers at London City Airport saw rapid growth between 2003 and 2008, doubling from around 1.5 million per year to over 3 million. Totals declined in 2009 and 2010, but have since recovered and in 2015 over 4.3 million passengers passed through London City. London City Airport