Recognizing an old viaduct in the city of Atlanta needed replacing, the Georgia Department of Transportation (GDOT) aimed to accelerate construction of the Courtland Bridge and employed an innovative procurement process and a design-build delivery method to fast track the work while collaborating with a multitude of stakeholders.
“It’s a 110-year-old bridge that is structurally deficient, and our goal is to replace it using an aggressive schedule to try to complete the work before the Super Bowl in 2019,” says Richard O’Hara, Project Manager for GDOT.
The 1,100-foot-long bridge bisects the Georgia State University (GSU) campus and is one block from the Georgia State Capitol. It was originally built as the Washington Street viaduct, connecting north and south Atlanta, which had been dissected by the railroad. Collins Street runs under the bridge, parallel to it, and provides access to several university buildings and parking garages. The bridge also crosses Decatur Street, the MARTA transit system and CSX railroad tracks.
“Along with the technical challenges, we also were dealing with the public and making sure their needs were addressed through the life of the project,” O’Hara says.
Initially, the department had planned on using a traditional, design-bid-build process, but after looking at the schedule, with a 24-month closure of the bridge, and the desire to open the bridge as quickly as possible, it switched gears and used a 50/50 technical vs. price procurement and a design-build delivery method.
“We thought with design-build, we would let the contractor drive the innovation,” says Andrew Hoenig, Project Manager for Innovative Project Delivery at GDOT. “That in turn, would accelerate the construction schedule.”
Typically GDOT awards about 80 percent on price and 20 percent technical, but for this job with its challenges, the department decided on the 50/50 balance, with schedule playing a bigger role, and the state paying a premium for speed.
“This is our first project that did not go to the low bid,” O’Hara recalls. “The incentive built in to the 50/50 best value design-build procurement was for them to compete for the right combination and win the job.”
The Need for Quick Construction
C.W. Matthews Contracting Co. of Marietta, Georgia, weighed several options before deciding on the winning strategy. The company received the $21 million contract to design and build the four-lane bridge in September 2017 and plans to finish it about one year later, in October. The bridge will have been closed five months, one less than GDOT required.
“We aligned the closure with the end of spring semester for GSU,” says Mike Nadolski, Project Manager with C.W. Matthews. “During summer semester there are fewer students around.”
Michael Baker International in Norcross, Georgia, served as the design partner and completed the design within months.
“We came up with a phasing plan for the most critical pieces of the bridge for the construction and got the design done to get those portions built,” Nadolski says. “We built the bridge from the ground up and had the foundations designed first and were under way with foundations in December. Some of the other portions of the bridge, toward the top, were still under design.”
Nadolski adds thanks to the Michael Baker designers for delivering the plans so quickly and to GDOT for its fast approval.
C.W. Matthews proposed installing micro-piles under the existing bridge, while traffic still flowed on it, using short equipment that fit under the old bridge. Micropiles use high-strength, small-diameter steel casings and threaded steel bars, according to GDOT. The piles were drilled to a depth of 80 or more feet to reach bedrock. Then grout was pumped in the drill hole to bond it to the bedrock. Each micropile can support a 550,000-pound load.
The design called for 13 bents, rather than the 28 supporting the old bridge. That allowed work to take place without interfering with existing bridge foundations.
Crews were able to install 10 of the 13 bridge foundations and some of the columns and support structures, with the old bridge operational. That allowed the road to stay open about three months longer than if traditional foundations had been used.
“Once the road was closed, all we had to do was set beams and pour the bridge deck,” Nadolski says. “That phasing was the biggest piece for acceleration.”
Another key was using high-early strength concrete, a mixture that cures quickly. The required strength, typically, occurred within 24 hours. C.W. Matthews successfully used that concrete mix on the Interstate 85 bridge repair last year.
Additionally, C.W. Matthews selected a 400-ton crawler crane, a Manitowoc MLC300 with a 300-ton Manitowoc 2250. The cranes were placed on 4-foot-tall pads to enable the counterweight to clear the fences and spread the loads.
“One of the ways to accelerate it was whether we could reach farther with our cranes,” Nadolski says. “That gave us the largest crane capacity with the smallest footprint.”
Stakeholder Collaboration and Employee Dedication
C.W. Matthews’ crews are working 24 hours a day, seven days a week, with employees typically working 60 hours to 70 hours each week.
“There is a huge commitment of time,” Nadolski says. “”This is beyond ordinary. We can do it in short spurts. It is very taxing on the people involved.”
Nadolski explains while C.W. Matthews can surge up to produce dramatically fast deliveries, trying to do so on every job is not possible.
“Of high value to the project, the entire team was working toward a common goal for the schedule,” O’Hara says. “The team went over the top and made several changes to accommodate the public.”
That includes stakeholder engagement with MARTA, CSX, the university, the general public and historic preservation interests. CSX and MARTA had representatives present during any construction over the tracks. CSX had a person on staff, 24 hours a day.
“Stakeholder cooperation is one of the unique features of this job,” Nadolski agrees.
C.W. Matthews developed a public-involvement plan and hired a coordinator to manage communications with the public. Historic preservation experts and the public asked the team to preserve a 1907 wall from a freight depot. When the original viaduct was built in 1907, the freight depot was cut in half to accommodate the bridge. One wall still exists and sits three-quarters of an inch from the bridge. The team demolished the old bridge and constructed the bridge without damaging the wall, maintaining it for future residents.
The project remains on time for an October finish.
“Accelerated bridge construction is an extraordinary result for the public,” Nadolski says. “It’s supposed to be through extraordinary design and ordinary effort. But in this case, it was a mixture. We are obtaining an extraordinary result from extraordinary design and extraordinary effort. We couldn’t be more proud of the commitment from everyone involved.”
Photos courtesy of C.W. Matthews Contracting Co.
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