The Georgia Dept. of Transportation plans to reopen a collapsed section of I-85 in downtown Atlanta by the morning of May 15, officially completing a marathon, six-week effort to restore the section of highway that normally carries nearly 250,000 vehicles a day. Contractor C.W. Matthews Construction will earn an estimated $3.1-million early-completion incentive for finishing the work roughly a month ahead of the original schedule.
GDOT Commissioner Russell McMurry praised agency staff and contractor C.W. Matthews for accelerating a reconstruction process that began shortly after a March 30 fire in a material storage area caused approximately 700 feet of elevated highway to collapse. Initial assessments projected construction to last at least until mid-June.
“Six weeks is an amazingly short timeframe to complete this project,” McMurray said at a May 10 press briefing. “At the same time, it is probably the most inspected, most scrutinized construction project Georgia DOT has ever undertaken, with our inspectors working on site around the clock. We did our due diligence each day and every step of the way.”
According to GDOT, the fast-track reconstruction saved time through the use of 24-hour accelerated curing concrete, prefabricated steel cross frames in lieu of cast-in-place concrete diaphragms and reinforcement of 13 supports that survived the fire. Weather was also on the project team’s side, with only one full work day lost due to rain.
Other issues proved more challenging, such as designing the prestressed replacement beams to support the curvature of the six deck spans being replaced. Two of the spans are trapezoidal in shape, transitioning from a skewed crossing at a local road back to perpendicular joints, explains GDOT Director of Construction Marc Mastronardi.
As a result, he says, “Twenty of the 61 beams are one-off castings to fit the trapezoidal shape.”
In all, crews used more than 2,100 cu yd of concrete and 505,000 pounds of steel to complete the structure. Mastronardi notes that the rebuild also proved to be a learning opportunity for the agency, beginning with C.W. Matthews’ removal of approximately 13 million pounds of debris in the days following the collapse.
“The demo equipment that could crush the concrete and separate the rebar in place, allowed for single handling of the debris,” he says. “Traditionally you will see elements cut, loaded and hauled off to later be broken down further and recycled.”
Mastronardi says the federal government will pick up 90% of the rebuild contract, currently estimated at $16.6 million. The federal government had already advanced GDOT $10 million in emergency relief funds.