ABSTRACT
Hathaway Bridge Replacement Design-Build, Panama City, FL
Tom Boyle, Project Manager, Granite Construction
Bill Crittenden, JV Project Manager, Granite Construction
Presented: Wednesday, May 12
8:45 am - 9:30 pm
The Florida Department of Transportation (FDOT) District 3 office, which encompasses the northwestern part of the state, has known for years that the Hathaway Bridge is functionally obsolete. The only direct link across St. Andrew's Bay for people traveling from Panama City to Panama City Beach is a bridge constructed in 1958 consisting of two lanes in each direction with no shoulder or pedestrian/bicycle travel lane. Due to the growth of this area over the last 40 years, this bridge has become inadequate to meet the traffic demands of the community as well as its projected future growth. Furthermore, the bridge is below the minimum navigational requirements for vertical clearance for the Gulf Intracoastal Waterway. After obtaining the necessary funding, the FDOT let the project using a design/build delivery method utilizing a combined technical score and price criteria. In August of 2000, Granite Construction was awarded the largest design/build contract ever let by District 3 in the amount of 81.5 million dollars.
The new Hathaway Bridge consists of two parallel bridges, each 80 feet wide. These bridges will have the capacity for four lanes of traffic in each direction with a separated pedestrian sidewalk on each bridge. They offer a 65 ft vertical clearance and 287 ft horizontal clearance at the channel. The superstructures of the bridges are designed with a single cell precast segmental box girder with seven 330 ft long variable spans and eight 200 ft long constant depth approach spans. Each segmental box girder bridge is supported by a row of single columns that are supported on a pile cap at the water surface that both bridges share. These waterline footings are supported on high capacity 60" diameter precast, pretensioned concrete cylinder piles, which were cast full length. The superstructures of both bridges were constructed using the balanced-cantilever method with one of the world's largest launching gantries. Custom built in Italy, this 900 ton gantry was shipped to the project, assembled, tested and put into service.
The 650 ft long, 45 ft tall gantry consists of twin triangular trusses supported by two movable legs which rest atop the pier segments. This gantry is designed to lift two 200 ton segments at the same time and position them for erection. Fully remote controlled, it can launch itself forward as the construction progresses from cantilever to cantilever. To put the size of the bridges and gantry into perspective, consider that when the gantry moves from one pier to the next, it places a point load on the just-completed cantilever equal to the weight of two fully loaded 747 jetliners.
As with most new bridge projects, the Hathaway Bridge also involves the demolition of the existing structure. Demolition becomes a project of its own, requiring the same detailed planning in order to safely and successfully complete the work. The existing bridge consists of the main center steel truss, continuous plate girder spans, and concrete beam spans. The piers are founded on 54" diameter concrete cylinder pile. A combination of mechanical methods and explosive blasting methods are being used to remove the old structure. Recyclable materials are being salvaged with the remaining portions of the bridge being transported offshore into the Gulf of Mexico to create artificial fishing reefs. A large marine equipment fleet was used for both construction and demolition.
This presentation will describe the general construction methods and materials used in the construction of the new Hathaway Bridge as well as the methods used for the demolition of the old Hathaway Bridge.
Credits
Owner: Florida Department of Transportation
Design/Builder: Granite Construction Co - HNTB
CE & I: Reynold, Smith & Hill
