Engineering the Home of the Braves
An Inside Look at the New SunTrust Park and The Battery Atlanta
By Lori Johnston
The problems were numerous.
Pipelines needed to be moved. A pond drained. Traffic and parking plans both designed and implemented. And all this in one of the tightest timelines, given a project of this magnitude.
But a team of engineers, assembled from both Atlanta-based and national firms with local offices, were ultimately tapped to ensure the Atlanta Braves’ new home in Cobb County would be ready by the major-league baseball team’s Opening Day: April 14, 2017.
“This was a very aggressive schedule,” says Emmy Montanye, Vice President and Principal-in-Charge at Kimley-Horn in Atlanta, which provided planning and engineering consulting for the entire project. It was no small feat, but the brand-new SunTrust Park, along with the surrounding mixed-use development project, The Battery Atlanta, was completed in a record-setting 36 months.
Mike Plant, the Atlanta Braves’ President of Development, jokes – now that the ballpark is open – how he would often apologize to people at the opening of a conversation and say, “I need this by tomorrow.”
In a project so time-sensitive and complex – one that spans 57 acres, cost $622 million for the stadium, approximately $400 million for The Battery Atlanta, and was riddled with site and design challenges – persistence, transparency and confidence among the engineers, architects, builders, contractors and property owners was crucial.
“We knew that we couldn’t be indecisive, otherwise we wouldn’t get to the finish line – and that finish line had no grace period,” says Plant. “My expectation of everyone who worked on the project was to bring their ‘A-game’ every day. And, to be incredibly collaborative, because we knew that if we didn’t work together and communicate well, we were going to miss key elements in getting this done. I credit everyone who was part of this team; they did all of those things very well and at a high level.”
Montanye and several team members recently strolled through SunTrust Park and The Battery, while the Braves were away from their new home. Montanye beamed while surrounded by her Kimley-Horn colleagues, including recent college graduates who joined the firm just at the beginning of the project.
“You really need to think through as a team how you’re going to build the project, what the sequencing is and what the phasing is, including how to issue and permit your design packages,” she says. “Then, you’ve got to be willing to make decisions based on all the information you have at the time and move on. As a team, we agreed that once we made a decision, we were living with it. All-in-all though, we made really good decisions.”
Some of those decisions included the addition of infrastructure not originally planned. Plant explains: “We built three different parking decks that were never part of the original plan. We added more roads, we built more vertical structures – again, not part of the original plan.”
Engineering ingenuity and quick decision-making helped create an economic engine that will support more than 5,200 jobs (including the construction) for the region, which pay a total of $235 million, according to Braves’ projections. SunTrust Park and The Battery Atlanta, which join other new projects in the Cumberland Community Improvement District, are expected to generate approximately $140 million in additional property tax revenue in their first decade alone. More than $30 million in hotel/motel tax revenue and more than $20 million in new sales tax revenue will be gained within the next ten years, according to projections by Brailsford and Dunleavy, an Atlanta consulting firm, which were provided for Cobb’s Competitive EDGE, a Chamber of Commerce initiative.
For many in the metro Atlanta area, it is hard to imagine that once vacant parcel, which has now been transformed into an economic and community development centerpiece. Over the following pages, the engineers who spent more than three years on the project give an inside look at some of the largest obstacles and innovative solutions that made it all possible….
Kimley-Horn’s due diligence, which began in September 2013 before the project was originally announced, served to identify site-related issues that would significantly impact cost or schedule, or were too substantial to justify the Braves purchase of the site.
One major hurdle was a three-acre pond with ducks and turtles, which could have hampered development or delayed the project significantly. “Typically, if there’s water on a property, you immediately have a lot of potential environmental concerns, and in many cases, it becomes a schedule driver,” says environmental engineer Marcus Rubenstein. He was an engineer with Woodard & Curran at the time of the project and is now a Senior Environmental Project Manager for Kimley-Horn.
A crucial first step was to determine if the pond was a viable natural system or man-made. A private investigation was part of a comprehensive due diligence effort that included finding documents from prior consultants and uncovering 20-year-old photographs that showed the land was once a parking lot with no pond. It was not a natural feature, they found – a good sign for greenlighting the project. Once the United States Army Corps of Engineers drained the pond, it discovered the pond was fed by a well and county water, instead of a natural stream. “Sure enough, we were all walking on chunks of asphalt,” Montanye says.
The Corps did not have jurisdiction over the pond, which meant the feature could be removed to build The Battery, as well as accommodate part of the plans for SunTrust Park. But first, local Boy Scouts relocated the yellow-bellied slider turtles to a new home on the Chattahoochee River, just three miles away.
The pond process took about five months, but could have delayed the stadium for years. “We would have just begun building the stadium if we were not able to quickly resolve this issue,” Rubenstein says a couple of weeks after Opening Day.
THE GAS LINES
Draining the pond was an initial step in solving another challenge: the gas lines that crossed the middle of the future ballpark. A 90-foot-wide gas line easement ran diagonally through the undeveloped site, which included two petroleum gas lines (one 42-inch and one 36-inch), as well as a 24-inch natural gas line.
“That was a huge hurdle and bottleneck for the project,” says Tim Santi, Principal in the Atlanta office of Walter P Moore, the structural engineer for SunTrust Park.
The underground gas lines, spanning all the way to Louisiana and carrying fuel to major users such as Hartsfield-Jackson Atlanta International Airport, needed to be moved. Kimley-Horn’s early review allowed it to develop a concept to relocate the gas lines, a complex process that required months of legal agreements, design and permitting. At the same time, the property was being re-zoned under the Atlanta Regional Commission’s Developments of Regional Impact (DRI) process administered by the Georgia Regional Transportation Authority. With 37 intersections and 30 driveways, it was the largest DRI in the state, to-date.
The team kept the current gas lines active and built new fuel lines, then decommissioned the abandoned lines. It was an orchestrated and staged process that amazingly did not hinder the flow of the petroleum, Montanye says.
“Obviously, this was the number one challenge because the lines needed to be moved before we could do anything else,” says Kate Triplett, an Associate with Kimley-Horn who oversaw the day-to-day civil engineering work for all the land development on the project.
The gas line easement also restricted the use of pipes and stormwater drainage in certain areas. “The challenge was that we couldn’t build on top of the lines and we wanted to be able to use as much land as possible,” Triplett says. The team needed a water drainage solution and found it in pervious concrete, which was used on all the parking lots in that area. “By using that material, the water drains through and we didn’t need to put in storm drainage.”
THE STORMWATER VAULT
The stormwater drainage solutions don’t end there, however. A hidden, yet massive system of the project is the stormwater vault underneath the Red parking deck. The approximately 440-by-100-by-11-foot basin can hold 4.2 million gallons of stormwater. “You don’t even know it’s there – the top of the basin actually creates one level of the deck,” Montanye says.
The “swimming pool”-like basin was designed to support the lowest level of the parking deck so that people could drive over it, says Martin A. Cuadra, Senior Principal at Uzun + Case, LLC. But the team also designed and constructed it to be able to support construction vehicles and equipment as heavy as a crane.
“When we excavated for the parking deck, we basically excavated another 10 to 12 feet and built the vault first,” Montanye says. “The columns of the parking deck actually come down through the vault.”
However, the same solution could not be used twice. When a surface parking lot was turned into the Delta Deck in order to provide more spaces at the stadium site, the team did not have time to create another vault. Instead, they used two smaller concrete chamber systems. Using this system, the team was able to save usable space and preserve the land value of the parcels in the mixed-use project, since developers would not need to add their own stormwater systems.
Ultimately, the master basin keeps the property from being littered with more than a dozen detention values, or systems, and it cost $2-per-cubic-foot less than a typical vault due to its massive size. “It was a lot of coordination and moving parts between the people involved, but it was well worth it,” says Kimley-Horn’s Triplett.
THE SLOPED, ROCKY SITE
Dave Miller, Senior Principal for NOVA Engineering and Environmental and one of the project’s geotechnical engineers, was no stranger to the project’s site. He conducted geotechnical investigations there starting in the mid-1980s as companies considered developing the property. The site’s topographical difficulties required an owner with both financial resources and ideas. “I kept waiting for someone to have the vision to see what could be done,” says Miller, who also worked on Centennial Olympic Stadium, which later became Turner Field.
One major challenge was approximately 90 feet of topographic relief on the northern end of the ballpark. “You had 60-foot cuts and those cuts encountered about 40 feet of rock,” Miller says. This required significant excavation and dirt removal. “When it was all ‘said-and-done,’ we took 24,000 truckloads of dirt and rock off the site,” says the Braves’ Plant. “It was a massive amount of rock, more than we originally thought.”
While the north side of the site presented rock, which took time to excavate, the old pond, with 70 to 80 feet of compressible soil, was to the south. The pond was between 20 and 30 feet below where the field level needed to be. The horizontal land planning required the geotechnical guidance and combined expertise of both NOVA and consulting firm Terracon to understand what was behind and beneath the elevation drop from the north to the southern part of the property, Plant says.
Despite the quick schedule, the geotechnical team needed time for the pre-loading, or “surcharging,” process, which required building fill slopes to let the soil settle. They excavated from the top down, instead of building it from the bottom up. After the settlement process, which took several months, they could build structures, such as the back wall that separates the red deck from The Battery.
“The important thing is addressing the settlements and making sure movement occurs before you build the foundation,” Miller says. “We had to get that wall in before starting to build The Battery.” While surcharging is a standard approach, the magnitude was uncommon. “What’s unusual is the depth of fill that had to be placed and the amount of settlement that was going to occur,” Miller adds.
THE CANTILEVER DESIGN
With many of the site’s engineering challenges solved, the next step in the process was structural. The stadium’s cantilever design is column-free, including the upper canopy, which is only supported on one end. “All kinds of places are cantilevering – or only supported on one end – and therefore hovering over your head, which is cool,” Santi says.
Walter P Moore’s project delivery process – or “Digital Practice” as they call it – allowed the design team to complete deadlines in just eight months. The firm developed a custom set of visual programming tools and code to parametrically and quickly make changes to the design model, as well as to control complex geometry. Nothing in the ballpark is orthogonal (at right angles), even though there are 180-foot-tall light towers and buildings sitting on top of buildings, Santi says.
“To meet the schedule, the structural steelwork was all done quickly through our ability to create highly sophisticated structural analysis and drawing tools,” he says. For example, the team was able to sidestep processes and shave a couple of months off the schedule by drawing the Tekla models that are used by a steel fabricator themselves in order to go straight to mill order.
This piece of the project truly demonstrates how engineering firms work with complex, fast-moving projects and must continually re-think the way projects are delivered. “This project is probably a little under-estimated,” Santi says. “Think about the steel members – beams, columns, girders, struts, trusses – in the building. Every one of those is cut somewhere in someone’s shop – they put holes in them and weld things onto them. But, it’s all got to fit together when it comes to the site. To be able to define that with drawings and models so that when it arrives, it all fits together like a Lego set…that is something that’s underestimated.”
THE STADIUM CANOPY
Instead of a retractable roof, the Braves chose a 108,000-square-foot canopy, which is the largest in Major League Baseball (MLB) – and they wanted the canopy to shade at least 60 percent of spectators.
To accomplish this, the Walter P Moore team developed an algorithm and codes to parametrically analyze thousands of canopies and modeled both the sun’s position and time of the year as it moves across the site. “We worked hand-in-hand with the architect, Populous, on that part of the project to come up with the best shape of the canopy,” Santi says. “We had to design not only the largest canopy, but also design it in record time…there’s no way to have done this without these electronic tools.”
As a result, it helped influence the design and shape of one of the stadium’s key features.
The seating bowl is faceted and has different slopes, treads and riser heights. Previously, structural engineers could not model each individual step, tread and riser, but Santi says they built the tools to electronically have the program recognize the steel frame, which supports the seating units in the model. “When you’re controlling all the geometry in three dimensions with these tools, you can make adjustments and therefore design even more complex structures,” he says.
The sloped seating bowls were intended to make spectators feel as if they are right on the field. “There’s a lot of work in the structural gymnastics to make the stadium as column-free as possible and really push everyone closer to the field. But, it’s all about the fan experience,” Santi says.
THE TRAFFIC PLAN
Kimley-Horn determined early on that the 57-acre site could handle traffic. Its due diligence for the Braves had identified 14 primary access points, from almost all directions, compared to two access points at Turner Field. A number of those access points offered four-lane and six-lane sections, creating high-capacity arteries in addition to the interstates.
Even so, “one of the greatest challenges was the traffic flow and it was one of the biggest concerns. Everybody was fearful of the traffic coming to the stadium,” says Rob Ross, Project Manager at Kimley-Horn.
“All along, we linked those 14 access points by asking ourselves, ‘Where do we have available parking?’ We further honed-in on who the owners or entities were that would be willing to enter into lease agreements with the Braves to provide game day parking,” Montanye says.
A key component, Montanye adds, was also not to bring all the cars to the ballpark, but to disperse the traffic. The ‘secret lots’ that fans used at Turner Field to avoid traffic helped develop the parking plan, says Ross. “One of the things that we tried to do was to build upon some of the successes that we heard about at Turner Field and use those solutions here. A lot of times you would hear stories of people who had their parking space and they kept it secret. It was their easy way in and out.”
With the leases in place, they determined what additional parking lots and decks were necessary for fans, as well as residents, workers and visitors to the Omni Hotel, The Roxy and the shops and restaurants in The Battery. “The approach from the beginning was to provide multiple parking areas. That way, parking is dispersed, and that in turn disperses the traffic,” Ross says.
Three pedestrian bridges, including one over Interstate 285, were also designed to separate people from vehicles, and to keep both moving. “There was also the added encouragement for people to buy their parking early, or use Waze to find alternative routes, or park early enough to avoid congestion around the ballpark. That’s what makes the plan successful – it’s not just one thing,” Montanye says.
Another necessary step was receiving MLB approval to push the weeknight start time to 7:35 p.m. since Kimley-Horn’s data and modeling showed that the peak traffic began to decline at 6:30 p.m. “We felt like it would definitely be an advantage,” she says.
The traffic and parking plan, which evolved over time, serves as an example of the collaboration and what Ross describes as “give-and-take” among the design, construction, engineering and development teams. “What might work best for traffic doesn’t necessarily work best for architects, or property ownership. There are a lot of places that we wanted to put parking that we couldn’t because we don’t control it,” he says. Kimley-Horn had access to data and resources, but also understood rush-hour traffic patterns and grasped an understanding of the time intervals around the stadium and The Battery, Plant says.
Thinking back to Opening Night, Ross is matter of fact, while still showing his problem-solving mindset: “It was three-and-a-half years of work, and it was a good day,” he says. “The engineer in all of us still sees things that we can improve, but the public perception was positive.”
Plant agrees: “When people woke up Saturday morning after our historic first game and the world as they knew it in Atlanta hadn’t come to a crash-and-burn end – I credit that to the team, years of effort and a lot of planning.”