"The aerial guideway has been one of the most challenging aspects of the project as we had to carry out this work safely above busy highways and in a congested area," said Larry Melton, Bechtel's executive director on the project. "Innovative construction techniques, the work of a dedicated and experienced crew, and patience from the public were critical to the successful completion of the guideway."

It was constructed by connecting more than 2,700 reinforced precast concrete segments, each weighing 25 to 40 tons. The segments were engineered for specific locations to ensure a custom fit.

Work will now focus on completion of stations and associated pedestrian bridges and pavilions, as well as on the process of connecting the Dulles extension to the existing Metrorail system.