Delaware Memorial Bridge Main Cable Dehumidification Modified Design-Build
New Castle, Del.
Award of Merit
Owner: The Delaware River and Bay Authority
Owner’s Engineer: AECOM
Contractor: American Bridge Co.
Structural Engineer & Construction Inspection: WSP USA
Contractor’s Engineer: WSP (Formerly Ammann & Whitney/Louis Berger)
Construction Inspection: AECOM and WSP
The $39-million main cable dehumidification system installation represents a dramatic advancement in bridge maintenance, according to the project team. Only the second of its kind in the U.S., the dehumidification system on the twin-span bridge forces dry air through the four bridge main cables to prevent deterioration from corrosion, the team says. “The system consists of a pipe running from the dehumidification chamber in the anchorage up along the suspender ropes of the bridge, with air flowing through the pipe until it reaches the injection port where it enters the cables,” the team says.
The dehumidification system for this design-build project will extend the bridge’s life span and prevent costly replacement of the bridge’s main cables, each of which is composed of 8,000 strands of steel.
Another key challenge involved maintaining normal traffic flow during construction to this vital crossing between Delaware and New Jersey. To minimize traffic disruption during the approximately 23-month project, the team completed work on an accelerated schedule by deploying multiple, simultaneous installation teams. Erecting scaffolding the complete length of all four main cables and training multiple teams of ironworkers at once helped deliver the project on budget and one year early.
Installing the system so quickly minimized inconveniences to the 80,000 travelers crossing the bridge daily.