The new Woodrow Wilson Bridge (WWB), is a signature crossing over the Potomac River just south of Washington, DC which links Maryland to Virginia. It carries twelve lanes of Interstate I-95/495 traffic. The bridge was designed to accommodate plans for a commuter rail system that may be added in the future. Its construction was part of the 7.5 miles, $2.5B Capital Beltway Interchange Project.

The new WWB is 6,000 feet and has four, side-by-side, 222 feet double-leaf bascule spans that provide navigational clearances of 175 feet horizontally and 70 feet minimum of vertical clearance in the span-down position, and completely unrestricted with the span raised. The bridge’s parallel double-leaf spans have 270 feet center-to-center trunnion spacing and an overall bridge width of 249 feet. The bascule span is supported on V-shaped concrete bascule piers. The new bascule spans weighing approximately 2,000 tons each comprise the world’s largest movable bridge. (The bascule spans of the new bridge are the heaviest movable load of any bridge in the United States, as 34M pounds of structure move to clear a ship through the channel.)

Features of the span include a composite lightweight reinforced concrete deck, sixteen moment-transferring span locks, sixteen tail locks, interlocking spans, redundant electrical power and control systems, eight warning gates, four barrier gates, four pedestrian gates, 32 submarine cables, sixteen motor drives, 12 control cabinets, eight motor control centers, 30 brake assemblies and a single control console fabricated from eleven individual control stations.

The bascule span and all ancillary devices are capable of operating in group mode, all eight leaves together, or individually. The redundant electrical control systems allow for seamless transition and operation in the event of a fault or malfunction from one control system to another.

Multiple levels of power redundancy also are provided through medium and low voltage switchgear substations in conjunction with two standby generators. Normal power is achieved through two separate substations and is interconnected to transfer power to the alternate power source should the primary source fail. In the event, both normal power sources fail two generators are provided capable of supply power for bridge operation.

H&H’s responsibilities included the complete design of the movable span superstructure, the trunnion towers, and the mechanical and electrical systems. H&H also provided construction support service engineering through project completion and construction inspection services for the entire electrical system for the duration of construction.

Project Accolades

Diamond Award
ACEC New York Engineering Excellence
Honor Award
ACEC National Engineering Excellence
Outstanding Large Project Award
ACEC Maryland Engineering Excellence