Dulles Corridor breakthrough

摘要

Excavation of a half-mile (approx. 0.8km) tunnel in Tysons Corner, Washington DC achieved breakthrough last week. The tunnel, which was under construction for 13 months and cost USD85M, is the most expensive section of the 23-mile(37-km) Dulles Corridor Metrorail Extension.It is 29ft (8.8m) in diameter and lies 40ft (12m) below a heavily congested section of road. The tunnel will connect passengers to two of the four planned rail stations in Tysons Corner.