On March 30, 2017, a massive fire destroyed an elevated portion of Interstate 85 in Atlanta, Ga., causing part of the highway to collapse. The fire forced the closure of all five lanes in each direction, creating havoc for 240,000 daily commuters. Along with the collapse, the heat of the fire caused significant damage to the cast in place and precast concrete and superstructure, as well as the intermediate piers supporting the spans in both directions. Georgia Department of Transportation (GDOT) bridge inspectors later found extensive delamination and cracking of the bottom flanges of the inverted-tee bent caps.
The project garnered national attention, putting the GDOT team under tremendous pressure, says Bill DuVall, state bridge engineer for the GDOT Office of Bridge Design in Atlanta. “There was no option but to deliver the project fast.”
The GDOT wanted the bridge back open no later than June 15, 2017, less than 80 days after the fire took place. To add further incentive, GDOT offered $1.5 million if the project was completed by May 25 (before Memorial Day) and $2 million if it was done by May 21.
“The timeline was the biggest challenge,” says Richard C. Potts, vice president of engineering for Standard Concrete Products (SCP) in Savannah, Ga. But his team was up to the challenge. They committed to the project before a contract was even written, and worked day and night casting girders in two plants round the clock to meet the schedule.
Within three days of the March 30 fire, DuVall’s team determined three spans in each direction had to be replaced, and they began working with SCP on a replacement strategy. “The existing superstructure utilized AASHTO Type V modified precast concrete beams, so whether to use precast beams or not really wasn’t a question for us,” DuVall says.
The new design included 61 precast, prestressed concrete bulb-tee bridge girders, and due to the geometry of the spans, only nine could be duplicated. The project also required 13 concrete columns, 4 concrete caps, and removal of 13 million pounds of debris. SCP had the AASHTO 63-in. bulb-tee forms at both of their plants in Georgia, allowing for rapid production. “Delivery of the girders was on the critical path for the project’s success,” DuVall says.
To ensure the project stayed on a fast track, GDOT bridge engineers stayed in constant contact with the contractor and SCP. “GDOT received shop drawing submittals even before the plans were approved for use on construction, and our precast/prestress unit of the concrete branch was available 24/7 for final inspection and testing prior to acceptance and delivery,” DuVall says. GDOT also provided oversized vehicle permits to streamline delivery.
By April 4—five days after the fire—work had already begun to expose the concrete cores on columns and footings, and on April 6 columns on the southbound lanes were already formed and placed.
By April 25 the final girder was placed on southbound span over Piedmont Road, and eight days later all of spans were placed and deck profiling and grinding had begun on the northbound bridge deck.
By May 12—a mere 44 days after the fire and more than 30 days ahead of schedule—the project was completed, and the new bridge was opened for traffic. The contractor and SCP received the full incentive payment for finishing ahead of schedule.
“SCP worked long hours to keep this project on track,” Potts says. Some of his teams worked 18 days straight, and conducted night casting to streamline the project. GDOT estimates that completing the project one month early achieved about $27 million in motorist savings.
“The reconstruction looks exceptionally good,” adds DuVall. “In a few years, the average citizen will never know there is a difference.”