Known as the economic jewel of Georgia, the Hartsfield-Jackson Atlanta International Airport (ATL) averages 275,000 passengers daily and has held the title as the world’s most traveled airport for over two decades. Located just 10 miles south of downtown Atlanta, ATL serves more than 150 U.S. destinations and upward of 70 international destinations in over 50 countries.

With a focus on meeting future aviation demands, in 2016, the city of Atlanta’s Department of Aviation set into motion a multibillion-dollar capital improvement program, ATLNext, to boost capacity, renew and replace existing facilities, and enhance ATL’s aesthetic appeal through a series of projects to be completed over the course of two decades. 

Specifically, this $6 billion master plan will modernize the Central Passenger Terminal Complex (CPTC), extend two concourses, construct multiple parking decks, add a sixth runway and expand cargo facilities. The program also paves the way for construction of a new hotel and travel plaza, as well as a mixed-use development with an initial 60,000 square feet of Class A office space.

Soaring Twin Canopies are Architectural Marvel

One area of the airport receiving major attention is the CPTC, which contains two independent facilities for domestic and international passengers. Upgrades to the domestic terminal include giant twin canopies built over curbside pick-up and drop-off areas at the building’s north and south entrances. Spanning eight traffic lanes, the soaring structures are designed to enhance the passenger experience by protecting visitors from the elements and improving traffic flow with elevated walkways.

The northside canopy was completed in October 2018 after a solid year of construction. Immediately afterward, crews turned their attention to the southside portion of the canopy project, which was finished 32 days ahead of schedule on August 29, 2019. 

Each of the monolithic arched canopies is 72 feet tall at its apex, 194 feet wide and 864 feet long. Combined, the canopies contain 3,500 tons of domestically sourced steel (the equivalent weight of nine Boeing 777 jets) and are covered in 19,776 square yards of lightweight ethylene tetrafluoroethylene (ETFE) panels embedded with more than 3,500 customizable LED strip fixtures for nighttime illumination. In addition to shielding airport guests from inclement weather, the highly translucent ETFE material allows natural sunlight to filter in while still offering protection against harmful UV rays.

“The canopies serve a functional purpose for the airport, but are also an icon for the city,” says Project Superintendent Kyle Orr of NSMS, a tri-venture that led construction of this dramatic new terminal entrance as part of a $265.5 million contract to improve various areas in and around the CPTC. “You see all this architectural steel spanning over the roadway, you see a specialty fabric going across the top of that, and there’s thousands of LED lights that can change and form different patterns. It’s an architectural marvel.”

In addition to the canopies, NSMS is upgrading all 38 existing domestic terminal entrances and associated facades, as well as improving the domestic terminal’s vestibule area, lobbies, and checkpoints to bring the nearly 40-year-old facility into the 21st century. The overall project is expected to be complete in April 2020.

A Major Logistical Feat

Significant planning and tremendous coordination have been essential in bringing this key element of the ATLNext program to fruition. The busy airport has to remain operational at all times, requiring round-the-clock construction so crews can maintain a steady pace while working around a near-constant flood of airline passenger traffic. “A typical project is a construction project with a logistics component. But this is a logistics project with a construction component,” says NSMS Senior Project Manager Justis Brogan.

Despite facing tremendous logistical obstacles, the NSMS team – which is utilizing a Construction Manager at Risk project delivery approach – is up to the task in meeting the owner’s requirements.

“From the beginning, one of the largest challenges has been pedestrian and traffic control and sequencing,” says Cameron Hudson, NSMS Project Manager. “To facilitate the safe and controlled erection of these canopies, we had to shut down entire roadways, implement traffic control systems, close certain vestibule entrances and exits to allow overhead work to occur during non-peak hours, and reroute the way passengers arrived to terminals from parking decks or drop-off vehicles.”

“This project is unique because the canopies have never been built before,” Brogan adds. “We knew we couldn’t leave areas closed at the face of the building where people flowed in and out during the day. So, we worked with the design team to engineer the connections in the canopy trusses in a way that allowed us to build them in nightly shifts.” 

Each canopy structure consists of 19 super trusses made of 20-inch, 18-inch and 14-inch steel pipe. The off-site steel fabrication alone took about a year to complete, and then the canopy structures were installed one at a time. But before erection activities commenced, crews had to prep the existing terminal facilities. “A significant amount of enabling work factored around Delta Air Line’s check-in facilities, which had to be relocated and rebuilt so we could have room to create the concrete pier foundation system,” notes NSMS Project Superintendent Anthony Gorzelnik. Existing utilities also had to be moved to make way for the project’s 38 piers, which are supported on micropiles as deep as 75 feet.

Mass concrete – an approach often used for large structures such as dams, bridge piers and other high-volume placements – was used to form the 21-foot-tall, 4-foot-wide piers, each one made of nearly 30 cubic yards of concrete. Mass concrete can be temperamental to work with, primarily because it has to cure at a lower temperature than it would organically to avoid concrete cracking, among other potential issues. As a solution, a specialized cooling system was installed within every concrete pier. “The cooling system in the piers is really unique. A series of plastic pipes carried chilled water through the center of each of the columns, and the engineering behind that is to control the temperature inside the column and make sure it stays very consistent,” Gorzelnik explains.

Though the outer sides of the canopy systems rest on these piers, the inner sides are supported by the existing terminal building, which had to be strengthened in order to bear the additional weight. “We had to go down to the apron level of the airport and install micropiles to the existing building columns and reinforce the foundation. Then we added stiffenerplates to the airport’s existing interior columns to further fortify the terminal structure,” says NSMS Project Director Dan Hobson.

Various innovative technologies were utilized to advance the construction schedule and streamline multidisciplinary collaboration. One example is 4-D scheduling, which uses realistic video simulation to bring projects to life by helping viewers more clearly visualize the sequencing of construction events. Additionally, various simulations can be run to detect potential issues before construction begins. “Creating a 4-D model not only assists in refining our schedule and work sequence, it also helps dramatically in communicating to the owner the construction impact on the traveling public,” Hobson says.

He continues, “The airport’s primary focus has always been to ensure the passenger experience is maintained, so passengers can get to their flights without being delayed by construction. To ensure we fulfill this objective, we also use passenger movement diagrams for each individual phase of work, and each individual area of work, to show where passengers will be in relation to active construction at each stage of the project.”

Lessons Learned

According to NSMS team members, they learned many important lessons while constructing the first canopy, which enabled them to complete the second canopy faster and more smoothly.

“On the north canopy, we experienced an engineering challenge related to long-span steel construction. The steel tolerances are such that the trusses needed to be erected within 1 inch of the design specifications to account for temperature fluctuations that, in a structure of this size, could cause the steel to move and shift substantially,” Brogan shares. About a third of the way through the north canopy build the NSMS team realized the steel members were moving in a way that could not have been predicted. At that time the team had to temporarily slow progress to make adjustments and modify the canopy’s alignment. “On the south canopy, we changed some of our erection methodology, and also how we tracked and modified our placement based on temperatures and environmental conditions so that we didn’t have to spend time making adjustments like we did on the north canopy,” he continues.

Gorzelnik adds, “We also learned a valuable lesson in controlling the pace at which all the different contractors provide their services or materials. There is a point in construction where you can move too fast. In our case, we let some trades get too far ahead, and construction was starting to affect passengers in more places than was necessary. On the second canopy we adopted a more standardized pace that enabled us to better manage logistics across the board.”

A Project of Significance

The NSMS joint venture – which has had around 60 personnel working throughout the entirety of the CPTC modernization project – is grateful for the opportunity to build what will surely become one of Atlanta’s most memorable landmarks. “The look and shape and form and lighting of these canopies is going to be an icon for the city; it’s definitely a once-in-a-lifetime project,” Hobson says.

Approximately 1.6 million on-site manhours will be logged by the end of the CPTC project, he adds. “We have just over 4,000 individuals registered to work on the job site. Also, the city of Atlanta is focused on partnering with equal business opportunity contractors, and has exceeded its goals in garnering participation from small, minority- and female-owned businesses,” he says.

Boasting a direct economic impact of $34.8 billion in metro Atlanta and a total direct economic impact of $70.9 billion in Georgia, ATL is one of the state’s most critical assets. As such, the ATLNext program will be monumental in ushering forth the next era of aviation dominance for Atlanta’s international airport.