Dulles Airport Tunnels

58,000 feet of tunnels

Automated people-mover system

US$3.4 billion development program

Challenges

The Dulles Development Program needed a network of tunnels for new, upgraded systems: an automated people mover (APM), a pedestrian tunnel, utility tunnels, underground baggage conveyors, and roads for airport tugs.
Adjacent airport operations and construction were successfully performed concurrently requiring multistaged construction sequencing.
Following the events of September 11, 2001, construction plans were reevaluated to reflect affected passenger figures and enhanced security requirements.
A second project phase was initiated following a reassessment of infrastructure requirements. Many specialist subconsultants were involved to complete the design of a pedestrian tunnel extension and other tunnels, including a covered baggage conveyor system with all necessary linkages.

Solutions

Detail design and design management was provided for the APM, baggage, and tug tunnels. Our scope included detailed design for the tunnels and associated structures, mechanical/electrical systems, ventilation systems, and the vehicle maintenance facility.
We led a team, including ten subconsultants, to finish the design of the pedestrian tunnel extension—the 2,800-foot-long, twin-35-foot-diameter, tunnel-boring-machine tunnels that link to a baggage conveyor tunnel; and a 2,400-foot-long extension of the west APM twin tunnels.
Tunnel designs were developed with special attention to fire and life safety.

Highlights

58,000 feet of tunnels bored, ranging from 18-foot diameters created by tunnel-boring machines, to 40-foot-wide New Austrian Tunneling Method caverns.
Ground conditions consisted of siltstone overlaid by weathered rock and residual soils.
Tunnels were constructed in the airport operating area under taxiways that remained operational throughout.
Eight stations and a maintenance facility for the APMs were constructed.

Project numbers

Phase 1: US$450 million construction cost
Phase 2: US$300 million construction cost
1,875-foot-long, 40-foot-wide, pedestrian-tunnel extension
700-foot-long, cut-and-cover baggage-conveyor tunnel