What might have taken months of lane closures took a fraction of that time during installation of a 2,860-ton, tied-arch cable-suspension bridge over a major highway. A project team with members hailing from seven countries used self-propelled modular transporters and intense logistical planning to place the P954 Flyover Bridge over the six-lane Khalifa Bin Salman Causeway in just 10 hours.
The 122.5-meter-long flyover links the U.S. Navy Support Activity Base in Bahrain to a port facility and will save the Navy an estimated $650,000 a year in transportation costs. The build-lift-move-install method had never been used before in the Middle East or by the Army Corps of Engineers.
According to primary contractor Contrack Watts, the diversity of the project team was a challenge, as participants came to the site at various times from Belgium, Abu Dhabi, Italy, Spain and the U.S., representing different languages and cultures. Moreover, the team had to deal with logistical and scheduling challenges in procuring building materials that would have to pass rigorous shipping and customs inspections. Another challenge was Bahrain's climate, often topping 100°F. Rigorous orientation and safety standards resulted in 308,000 labor-hours with no lost-time incidents.
Designer HNTB revised the design from a multiple-span, prestressed-concrete structure upon request from Bahrain officials who were concerned about the proposed overnight closures to the heavily traveled causeway. The revised single-span structure and fast-track construction method reduced causeway closure times to hours from months while increasing the safety of workers and driving conditions.
Crews built the 16-m-wide, 27.5-m-tall, tied-arch cable-suspension bridge on temporary falsework 250 m from its permanent location. The move entailed hanging the bridge from 2-in.-diameter high-strength rods attached to lifting beams installed at each end. Experts worked three days to prepare the bridge for the six-hour move. They analyzed the causeway pavement to ensure it would handle the bridge weight, manipulated each wheel of the two mobile transports' set of 48 and monitored the 12-axle transporter units that lifted the bridge onto abutments.
The bridge project is part of a $580-million, five-year effort to double the base of the U.S. Navy 5th Fleet Command, which encompasses about 6.5 million sq km of water, spanning the coastlines of 27 countries. The program includes constructing a perimeter fence, port operations center, administrative and recreational buildings, barracks and waterfront development to support navy and coalition ships. The bridge will directly link the support activity base to the U.S. Navy port facility over the major traffic corridor.
Owner: U.S. Army Corps of Engineers
Contractor: Contrack-Nass Joint Venture
Lead Design Firm: HNTB
Third-Party Bridge Design: Tony Gee & Partners