Opportunity
In 1833, construction was completed on a bridge spanning the Chattahoochee River and connecting the communities of Columbus, Georgia, and Girard, Alabama. Designed and built by Horace King, a former slave and respected bridge builder, it consisted of a 560-foot (170-meter) lattice truss.
The bridge was destroyed by a flood in 1838 and replaced by King in 1841. In 1865, during the last major battle of the Civil War, the bridge was destroyed once again by Union General James H. Wilson.
The bridge was rebuilt for the third time in 1866. In 1905 a new steel girder bridge was constructed that could handle the city’s new electric streetcars. That bridge was replaced in 1920 by a 639-foot (195-meter), nine-span, earth-filled spandrel arch, but by 2000 the structure had deteriorated and was closed to traffic.
The city of Columbus decided to rehabilitate the bridge to provide pedestrian access between the Chattahoochee RiverWalk, a 15-mile (24-kilometer) riverfront park on the Columbus side, and the 1.2-mile (1.9-kilometer) Riverwalk park on the Phenix City side. Rehabilitation was made more difficult by the absence of plans for the 1920 structure.
Solution
Mott MacDonald was retained by Hecht Burdeshaw Architects to serve as the structural engineer of record for the project. The design required extensive field inspections to develop the initial plan for remediation, along with research into historical closed spandrel arch structures. Assumptions on how the structures were constructed were necessary, based on information obtained from similar bridges. The design and detailing of arch, overhang, and abutment required close coordination with the bridge contractor to address actual field conditions. (See video.)
As part of local restoration efforts, the Eagle-Phenix Dam was removed in order to renew the river’s natural flow, expose whitewater rapids submerged for almost 200 years, and support two miles (3.2 kilometers) of riverine fish and bird habitat. Plans were made to create the longest urban whitewater rafting course in the country.
Existing bridge piers were encased as part of the rehabilitation, increasing their width from 8 feet (2.4 meters) or less to 12 feet (3.6 meters). Because of concerns were raised that whitewater rafts might broach against the wider piers, we retained the McLaughlin Whitewater Design Group to configure the piers.
Outcome
The Riverwalk program combines environmental restoration, economic development, and walkable communities. After the completion of the historic 14th Street bridge, two new hotels were constructed on the Phenix City side of the river at the terminus of the bridge. Visitors to Columbus increased by 30% from 2012 to 2013, reaching a total of 1.7 million.
Our subcontractor configured the bridge piers to create a “pillow” of water upstream, reducing the tendency of whitewater rafts to broach.
The project preserved a structure of historic relevance, maintaining its iconic image and demonstrating that historic preservation, environmental restoration, and economic development can successfully coexist.