A new airport rail network has started operations at Dulles International Airport in the US.

Planning for the $1.5bn train system began 15 years ago.

The completed project covers four miles of track at speeds of 42mph and features 29 electric rail cars on rubber wheels that can accommodate 50 passengers.

The train, known as Aerotrain, runs from airport’s baggage claim area through to its main passenger terminals and boarding gates A, B and C.

The train does not serve gate D or the international arrivals terminal.

The AeroTrain is part of a $3bn expansion launched a decade ago, which comprises building a fourth runway, parking garages, 15 new gates, concourse and terminal expansions, and a control tower.

The AeroTrain system replaces most of the existing cramped, diesel-fuelled Mobile Lounge system. However, half of the 49 mobile lounges will stay in service indefinitely.

The airport is expected to have a Metrorail station by 2016 when the Silver Line is extended from East Falls Church to the airport and into Loudoun County.