With aircraft operations at Dulles nearly 560,000 annually, expanding the current three-runway system has become a necessity. The first three runways at Dulles date back to the Airport's 1962 opening date. The current Airport master plan allows for a new north-south runway (opened in 2008) and a future east-west runway (the fifth runway). Both runways were approved by an FAA Record of Decision in 2005. Construction of the fourth runway began in 2006, but fifth runway construction is not yet scheduled.
The fifth runway will run parallel to existing runway 12-30 along the south side of Dulles Airport property. The runway would be roughly parallel to U.S.50, west of Chantilly. It will be approximately 10,500 feet long and 150 feet wide. When completed, the new runway will be named Runway 12R-30L and the existing parallel runway will be renamed 12L-30R. The numeric designation is the runway's compass bearing in degrees, divided by 10. The letters stand for left and right.