The initial half of the Dulles Metrorail extension will cost $180 million more than earlier estimated and may not be finished until early 2014, according to a report prepared for the Federal Transit Administration.

The document, unveiled Monday, delivered the highest price projection yet for the 11.6-mile first phase – arguing that to run the track from west Falls Church to Reston will cost $2.83 billion. The figure, the report said, does not include potential “upward adjustments for project complexity, additional organizational risks, or cost growth to date.”