Since June 2008, C.W. Matthews Contracting Co. Inc., based out of Marietta, Ga., has been working on a $16.7-million bridge replacement contract on State Route 280 (SR 280) awarded to them by the Georgia Department of Transportation (GDOT). In addition to the replacement of the bridge, the project includes 1.224 mi. (1.9 km) of road widening and the construction of bridge approaches. The project is located within the jurisdiction of GDOT’s Metro Atlanta District office.
The bridge traverses railroad tracks and the Chattahoochee River, which also serves as the boundary between Cobb and Fulton Counties. The street name of SR 280 is different in each county; in Cobb it is called South Cobb Drive, and in Fulton it is called James Jackson Parkway.
The old bridge and roadway consist of only two lanes for travel. According to Ryan Beech, project engineer of Matthews Contracting, “Once completed, there will be four travel lanes with a turning lane in the center.”
Furthermore, the widening is needed because the project “ties into four lanes on both ends — we’re doing the middle,” explained Mickey McGee, district construction engineer in the Metro Atlanta office.
To keep traffic flowing, vehicles will use the old bridge while half of the new bridge is being built. Once the first section is completed, traffic will move to it, and the old bridge will be demolished. Then, the remainder of the new structure will be completed. Rogers Bridge Company Inc., Atlanta, Ga., is the subcontractor responsible for the construction of the new bridge and the demolition of the old bridge.
Like the old bridge, the new structure will be concrete as well. Rogers Bridge has used “several different types of cranes during the first few stages of this project,” explained Beech.
So far, the company has made use of two Kobelco 1000 cranes with a lifting capacity of 100 tons (90 t) each to set the concrete beams for the bridge. Also on hand are a Link-Belt 138 crawler crane and a Link-Belt 138 truck crane; each have 75-ton (68 t) capacity. Some tasks that the Link-Belts are used for include setting overhangs and assisting in moving materials.
Another aspect of the project involves raising the roadway’s grade. There is an elevation change of 8 ft. (2.4 m) from the existing roadway to the new roadway elevation at the bridge. As a result, “the grade has been raised on the new bridge,” McGee stated. The grade for the approaches must be adjusted as well.
The roadway portion of the project consists of more than 100,000 cu. yd. (76,000 cu m) of fill and extensive pipe work. In addition, a total of six mechanically stabilized earth walls will be installed.
According to Beech, many pieces of equipment have been brought in for the project. A Caterpillar 330C excavator is being “used to lay pipe, excavate for walls, and stream relocation,” he said. The contractor also is making use of Caterpillar D-4G XL and D-6N XL bulldozers for work on the rough grade fill and cut areas. Two types of roller compactors are readily available, Beech explained, including “the Caterpillar CP-563E (Sheepfoot) to compact fill material and a CS-563E to compact subgrade and graded aggregate base.” Also mentioned was a Caterpillar 140H motorgrader, which is being used to fine grade the roadway prior to paving operations.
Even though most would consider this project run of the mill, Mark McKinnon, Atlanta regional media coordinator for GDOT, made clear that “anytime you [work] over a body of water, regulations have to be met.” There are stringent environmental rules and regulations that must be followed from the beginning.
The Chattahoochee River is quite large, so the contractor and GDOT make sure that the necessary environmental protections are in place, including erosion control systems, from the start of construction thereby requiring the contractor to work around them.
Special caution is being taken because of an endangered species, the barn swallow, which nests in bridges and culverts in this region. “A certain time of the year we cannot remove their nests,” McKinnon said. “We schedule work on other parts of the project while they are nesting.”
Even so, McGee confirmed that the project is halfway done and on schedule for the June 30, 2010, completion date. CEG