The Dulles Metrorail project is a 23-mile extension of the existing Metrorail system from East Falls Church to the Washington Dulles International Airport. Phase One is a $1.6 billion design-build project that included the Tyson’s Guideway, with more than 5.2 miles of precast segmental concrete aerial structures through Tysons Corner, Virginia’s largest employment center.

When all phases are completed, the system will provide rail service from the airport to downtown Washington, DC. The Tyson’s Guideway precast segmental concrete bridges total over 5.2 miles in length with a maximum span length of 173′. Twin structures supported on common piers are used, with one box girder supporting each track. The precast superstructure segments are typically 15′ wide, 10′ long and are prefabricated on airport property. Spans are typically 130′ long, simply supported with no closure joints, and segments are erected span-by-span using a self-launching overhead gantry. Segments are erected in a balanced cantilever over I-495.

​Corven Engineering, an H&H company, served as the engineer of record for the segmental superstructure design and provided construction engineering. Services included Initial design and bid quantities; final design and specifications; integrated shop drawings for the precast superstructure segments; construction analysis, post-tensioning stressing data; review of step-by-step erection procedures; review of three-dimensional casting geometry; engineering support during construction; and on-site technical support.