Gerwick has provided numerous contributions to the design and construction of the new Cooper River Bridge.
Specialist design services included:
- Ship collision risk analysis
- Design of artificial pier protection islands for the main bridge piers
- Design of drilled shafts foundations for the main spans and high level approaches
- Design of Town Creek fender protection systems
- Design of scour protection measures
- Design of sheet-pile cofferdam cells for protection of existing bridge piers
Construction of the new bridge took place in close proximity to the existing Silas Pearman and Grace Memorial bridges. Construction of the artificial islands involved dredging in excess of 500,000 cubic yards of material in the area around the existing bridge piers.
The 54-foot diameter sheet pile cells are approximately 50' tall and enclose the bridge footings and battered pile foundations, allowing the piers to function as free-standing columns during the period of construction. The sheet-piles were driven into the Cooper Marl, located at elevations from 40ft-70ft below mean sea level.
The construction of the drilled-shaft foundations and artificial pier protection islands for the new bridge involved a number of construction sequences, including dredging and infill of quarry run and rock, for which the sheet-pile cofferdam solution provides a safe and versatile method of stabilizing the piers of the existing bridges during construction of the new bridge.
