ALDOT, Scott Bridge Traverse ’Bama River With $9.8M Span

Mon August 13, 2001
Giles Lambertson

Before there was Interstate 65 s1icing southward through the heart of Alabama, there was U.S. 31. It cuts all the way from Tennessee on the north to Mobile Bay in the Gulf of Mexico.

To make the trip, highway travelers must cross the Alabama River between Prattville and Montgomery. The old turn-span bridge that served the highway for so long now has been replaced.

Scott Bridge Company Inc. recently completed a $9.8-million replacement span that will serve southbound U.S. 31 motorists, complementing a separate bridge that serves northbound travelers. The job was contracted in May 1999.

The company called upon years of experience in marine and dryland construction to make quick work of the project. The job was blessed with good weather and a good working relationship with a principal subcontractor, said Mike Terrell, Scott Bridge vice president.

The new span was built adjacent to the old one so rerouting of traffic wasn’t necessary. The Alabama Department of Transportation (ALDOT) contracted with Reese and Howell, a Montgomery contractor, to build the connecting highway. The approaches are expected to be completed and carrying traffic to the bridge by July.

Total length of the new structure is 2,310 ft. (704 m), which includes four main spans across the deepest part of the Alabama and relief spans that connect with shore on the north and south ends.

Scott subcontracted the main pier work to a Tampa, FL, firm, Case Atlantic Co. It was Case Atlantic’s responsibility to drill and pour six shafts for piers that have a diameter of 12 ft. (3.6 m). The piers extend through the length of 60-ft. (18 m) caissons and another 30 to 40 ft. (9 to 12 m) into soil beneath the river.

Working from barges, the subcontractor employed a Steven W. Hain drill attachment on one of Scott Bridge’s cranes, a 4000 Manitowoc. Drilling spill was carried away on a separate barge, and other erosion control procedures were followed to mitigate environmental damage.

Using a vibrating hammer, the company methodically sank and worked its way through the caissons, eventually fitting the interior of the shaft with a rebar cage and pouring concrete to form the piers.

“It went very smoothly,” Terrell said. Looking back from the vantage point of a completed project, he said the biggest “thrill” of the overall job was how well the pier work proceeded.

So many things can go wrong in such an undertaking, he observed, but none of them did.

“The weather worked well for us,” Terrell said, “and the drilling subcontractor and our people worked well together as a team.”

Michael Harper, who was ALDOT project engineer, agreed that the pier work went exceptionally well.

“Case Atlantic did an outstanding job,” Harper said. “You can have major problems with drill shafts that large. But there were none.”

With piers in place, the span work proceeded. The first segments of the bridge — “relief spans” that give the river a place to surge under the highway at times of high water — are formed of pre-stressed concrete girders 54 in. (137 cm) tall and 100 ft. (30 m) long.

Motorists traveling south will ride smoothly onto and across 11 of these spans before reaching the deeper portions of the Alabama. On the south end, four more of the 100-ft. (30 m) spans complete the crossing. The pre-stressed concrete girders were provided by Tindall Concrete Products of Atlanta, GA.

In between the two relief span segments, Scott formed the main bridge from a combination of girders, some of which are pre-stressed concrete and some, structural steel.

Scott engineers talked the ALDOT into subbing weathered steel girders for the regular steel ones first specified. The “weathered” steel girders features an oxidized brown crust that seals the beam from further corrosion and doesn’t require painting. The substituted steel is expected to produce saving for the state in maintenance costs.

To handle all of these girders, the company employed a variety of cranes.

Working from barges were the 4000 Manitowoc and a 4100 Manitowoc. An American 7260 also was used, the capacities and functions of the cranes being pretty interchangeable, Scott said.

Working from ground or from the incrementally growing bridge itself were a Link-Belt LS138H and a pair of American cranes, a 5299A and a 7250

Scott had a crew of about 40 people on the project.

The four structural steel spans in the heart of the bridge measured 180 ft. (55 m), 225 ft. (68 m), 225 ft. (68 m) and another 180 ft. (55 m). The steel girders were fabricated by Augusta Iron and Steel, a Georgia firm.

This Alabama River project is old hat for a company that for almost 70 years has been crossing bridges when it comes to them. Founded in 1933, the company has grown to one with an annual business volume of $50 to $60 million.

Ike Scott is president of the firm, the headquarters of which is in the eastern Alabama city of Opelika. Terrell has been with the company for 13 years.

Specializing in railroad, highway, marine and heavy engineering, the company typically has 15-20 projects going at any one time in Alabama, Georgia, South Carolina and Tennessee. Much of it is DOT highway river crossings and railroad bridges for CSX and Norfolk & Southern railroads.

In April, for instance, Scott crews were constructing twin bridges across the Tennessee River near Florence in northern Alabama, erecting a 3,000-ft. (914 m) span across the Tombigbee River in western Alabama, and replacing steel trusses on a Norfolk & Southern bridge across the Coosa River at Childersburg, AL.

Scott Bridge also does design-build work. Among such projects were a facility for the 1996 Olympics in Atlanta and an emergency construction project following flooding.

For more information, visit www.scottbridge.com.