Our excellent reputation in tunnel design is earned through experience, including the world’s largest diameter soft-ground tunnel; the world’s first and only vertical, continuously spiral-lined shaft; the largest deep-transit station in soils in the United States; and instrumentation for major tunnel installations.  Our staff is experienced in designing and managing construction for tunnels that involve a wide range of excavation techniques, including drill and blast, roadheader, tunnel-boring machine, earth-pressure-balance machine, slurry machine, sequential excavation method, micro-tunneling, pipe-jacking, and directional drilling.