ENR Texas & Louisiana: Delays, Complexities Test Team on Southwest Project
by LOUISE POIRIER
Two buildings, totaling more than 800,000 sq ft, an eight-story parking garage and a 400-ft pedestrian bridge, all built simultaneously with different construction methods, comprise Southwest Airlines’ (SWA) new Wings Facilities project, located at the airline’s corporate campus near Love Field in Dallas. Construction costs on the project total $200 million.
McCarthy Building Cos. and architect BOKA Powell are tackling this immense project, and together with SWA have overcome obstacles that included limited site access, inclement weather and a tight schedule.
Each of the four components on the Wings project has a different purpose. The 380,000-sq-ft Leadership Education and Aircrew Development (LEAD) Center houses 18 flight simulators as well as workshop and functional support areas with large spaces for classroom training, explains Robert Dorsey, director of corporate facilities for Southwest Airlines.
The 425,000-sq-ft, six-story office building “includes a full-service kitchen, dining area and spacious conference rooms,” he says. “In addition to surrounding surface-lot parking, an eight-level parking garage with 1,950 spaces provides convenient parking for employees and visitors.”
Additionally, a T-shaped, fully enclosed, 400-ft pedestrian safety bridge connects SWA’s existing headquarters with the new buildings.
“It provides a safer way for employees to travel between the east and west sides of Southwest’s corporate campus by eliminating the need to leave the secured portion of campus,” Dorsey says. “Additionally, it keeps employees from having to cross two busy public streets, DART light rail tracks and commercial train tracks at ground level.”
While the types of construction used on the project aren’t especially unique, the mix of different product types being built concurrently using fast-track delivery is rare, says Dan Cummings, project executive, McCarthy.
“The LEAD Center is a hardened, cast-in-place concrete frame with a 60-ft-tall architectural precast facade. The attached office building is a structural concrete frame with an insulated metal panel and glass curtain wall facade,” Cummings says. “The parking garage is a precast structure erected on a cast-in-place foundation, and the elevated pedestrian safety bridge utilizes long-span trusses erected upon bridge columns and bents.”
Both economics and performance criteria dictated those choices.
On the LEAD Center, for example, the flight simulators that live within that building are worth about $13 million apiece, “and there’s space for 18 of them, so add that up and that number gets huge really quick,” Cummings says. “The structure they live within and the facade that’s on that building will withstand an F3 tornado.”
Adds John Orfield, principal-in-charge of design at BOKA Powell: “There’s a double roof, the walls are concrete on the outside, there’s a concrete frame and all of that is done to make it as safe as possible.”
The No. 1 priority on this job when the project team assembled in mid-2016 was having the LEAD Center portion of the project ready to begin flight simulator setup by May 15, 2017, just 53 weeks from the anticipated start date, Dorsey explains.
“It was necessary to achieve this milestone to allow time for simulator assembly and FAA validation to occur in time to begin training pilots in the LEAD Center by August 1, 2017,” he says.
This business decision correlated with SWA’s plan to replace existing aircraft with new models and add flights to new destinations—which meant that pilots had to be trained on the new aircraft by a certain date or all related schedules would be thrown off, Orfield adds.
“There were multiple packages that were designed in order to get construction started as soon as possible. They started working on the site before all the drawings were done and proceeded all the way throughout the project,” he says. “We had people on the construction site doing drawings and working on it while they were building on it.”
Having the design team located on site allowed it to expedite review and response times and made it “able to assist the contractor directly in the field on an immediate basis,” adds Lyn Diefenderfer, project architect with BOKA Powell.
SWA chose a construction manager at-risk delivery method. While the CMAR delivery wasn’t unusual, SWA brought the construction manager on during preconstruction and asked that in addition to the estimating team’s involvement, the project manager and senior superintendent be brought on full-time as well, Dorsey explains.
“This allowed these team members to be a part of the evolution of documents, and it provided the opportunity to plan and schedule the work in a manner that created a much greater probability for success,” he says.
Part of the challenge of delivering the flight training area on time was that the Dallas construction market was booming as the project got underway, making it more difficult to select the right team from the outset.
SWA, BOKA Powell and McCarthy hand-selected staff, and when it came to hiring contractors, they were “selected based on capabilities and capacity to perform, rather than just a low number,” Cummings says. “We knew they had the people available to man the project, not only the quantity of people, but also the right people to put on it, to make sure it was successful.”
The weather became another obstacle to the 53-week turnaround on the simulator portion of the LEAD Center.
“We had planned to work six days a week and long days from the start, but we anticipated that we’d have maybe 15 days of impact from weather,” Cummings says. “We eventually had 36 days [of weather] during the LEAD Center building structure and enclosure activities. So that was an additional 21 days that we had to overcome. You add up 21 Sundays and it really just doesn’t get you there because we were completing the structural portion of the project in 26 weeks.”
Rather than pushing the entire team to work 24-7, McCarthy and its subcontractors decided to use a “skeleton crew” of sorts—a smaller crew that came in after hours to rearrange materials and clean up after the day’s work. That crew also put everything in place for the following day’s tasks.
“We were just amazed at how much that actually worked. It not only helped our crews be more productive, it saved the owner costs and the weather-impact cost that would have been associated with working a bunch of crews for a lot more hours,” Cummings says.
Site logistics added another twist. A railroad track curves around the north and east perimeter of the site, while the existing SWA facility sits to the south. An operating medical facility is located to the west.
“There’s one roadway next to that medical facility that comes into the site, and it’s on Research Road. And that was the only way to get into the site without crossing the railroad tracks, which on the east side included the DART rail tracks,” Cummings says.
To avoid having to coordinate rail crossings for material deliveries, the project team had no choice but to work with one entrance and “just be extremely diligent to keep it open,” he says.
“Our superintendents did an excellent job of knowing the project well, having daily meetings with the subcontractors. They started every day with a 6 a.m. meeting to coordinate that day and to look ahead at the coming days. That was also the time to make any adjustments to the plan that were necessary due to unforeseen conditions like weather or material that didn’t show up or who knows what. Things happen,” Cummings says. “When you’ve got 800 to 900 people on site in a day and the materials are coming in at a rapid pace, there’s all kinds of opportunities for problems to arise.”
The volume of concrete needed for concurrent construction of the four project components was a concern from the start.
“Just the volume of concrete to feed all of those different entities at one time, we were looking at almost 1,000 cubic yards per day at times, and we couldn’t get one concrete supplier that could accommodate that kind of volume,” Cummings says. “So we ended up signing up three different concrete suppliers to get the volume there we needed to complete the project.”
Additionally, concrete materials from the demolition portion were taken to the same facility that road materials were purchased from, he adds. “In effect, the demolished materials came back to the project and were used for road base, both temporary and permanent.”
A high percentage of materials were purchased locally, including lumber, concrete and steel. To stay on schedule, the contractor also controlled and performed the majority of the concrete work with its own crews.
The amount of concrete used across all four components totaled nearly 125,000 cu yd. Since the project sits on a drilled-pier foundation, not a mat slab, the largest single concrete placements were on the elevated decks.
“McCarthy utilized laser scanning technologies to confirm the flatness and levelness of the concrete flight simulator pads that had very close tolerances that had to be met,” Cummings explains. “It was used in lieu of field measuring with tapes for composite metal panels and for miscellaneous steel fabrications.”
3D cameras helped confirm positioning of in-wall items before closing them up with drywall. The cameras also provided SWA with as-built information that can be used during future remodels.
“McCarthy also used GPS technology to create a record of all utilities that were installed within the site. The records include both positioning and elevations of these items and can be referenced at any time,” Cummings says.
Construction of the LEAD Center was the most complex task on the project. The level of security on the areas with access to the flight training areas was highly restricted, Diefenderfer says.
“Heavy coordination with security consultants and SWA employees as far as how people get in, how people move around and controlling where those people go [was critical]. It’s another one of those key things that is beyond a normal office building that we do,” he says.
While the simulators are located on the LEAD Center’s ground floor, a full level below that contains the function and support spaces, Cummings says. Above the simulator level are three more floors.
“One of the more unusual factors we have on this building is going down the middle of the building is a circulation spine that is for the actual delivery and removal of simulators,” Orfield says.
A 450-ft-long, east-west corridor separates the north and south simulator bays, which hold nine units each. “It’s an open area where they can install or remove any simulator they want without interfering with other simulators that are in place,” Cummings says. “It’s the same construction as the rest of the simulator bay floors, just a reinforced-concrete deck that happens to be part of that floor. They call it the spine because of its location—the simulators move in and out through there.”
Pilots enter the simulators from the second floor because of the height of the units.
To help with pedestrian circulation and avoid forcing people to walk up and down the 450-ft-long corridor to go between the north and south training areas, the project includes two 30-ft-long by 14-ft-wide drawbridges, also on the second floor.
“One is on the west half of the building and one in the center, and that allows you to pass from the north side of the building to the south, and vice versa,” Cummings says. “The trick with the drawbridges was making sure that we coordinated very closely all of the attachment points of the drawbridges and the alignment and the attachment points and the seats for those bridges.”
Another crucial portion of the spine are the two 2-ton bridge cranes installed overhead on railings to help with installation and movement of the simulators.
“There’s one crane on the south bay and one on the north bay. The challenge with this building was that it is so long that there has to be expansion between the two halves of the building to allow for proper movement,” Cummings says. “It’s unusual for an overhead crane like this to pass an expansion joint like we have.”
To solve that, the project team worked closely with the crane manufacturers to first develop the expansion joint for the rail system and then McCarthy had to engineer and install all the attachment points for the multiple rails, Cummings says.
“The span on them is about 50 feet by 450 feet, so it’s the 50-foot width that runs along the rails. The crane itself, the structure of the crane, just travels in an east-west direction, then you can drop the hook down to help with the maintenance and installation of the simulators themselves. So it’s not a conventional crane with a boom,” he adds.
The installation of cranes was done using existing attachments and technologies. “They’re connected through the use of embedded bolts and plates, but it was making sure that they had the correct capacity and that the alignment was done with pinpoint accuracy, because there wasn’t a whole lot of tolerance in the system to be able to make it work,” Cummings says.
Reaching the Finish
The office building and the education and training areas of the LEAD Center feature raised access flooring. “It allows a lot of flexibility, a lot of change over time, and it’s not typical,” notes Orfield.
But it does add another scope of work that wouldn’t typically be included on something like an office building, Cummings adds.
“Normally, you’d build this space out, you’d build the walls, put the flooring in,” he says. In this situation, while some walls still extend from the concrete structure up to the structure above, others must be built upon the access flooring itself. “So you had to build some of your walls, install your access flooring and then build other walls on top of that and then put your carpet or tile finishes on top of that,” he explains.
Throughout the office building, floors were raised 9 in. from the structural floor, while in the training and educational spaces of the LEAD Center, it’s 24 in. to allow for a variety of functions, Cummings says.
SWA is targeting LEED certification on the project, although some aspects of the facility limit its ability to secure LEED points.
“Given the hardened nature of the [LEAD Center] building, there are a lot of opportunities within the LEED system that would not be appropriate. Since we didn’t have windows, there’s not the same opportunities for natural daylight or the same opportunities for ventilation that might get other points in other buildings naturally,” Orfield says.
Additionally, while the LEAD Center currently houses 18 flight simulators, the design team’s plans already allow for the addition of up to eight more, Diefenderfer says. “We’ve done the forethought on the design of the mechanical and electrical systems so everything is there for that building addition without having to do additional utilities down the road,” he says.
The project team delivered the first two flight simulators into the LEAD Center on May 15, 2017, as scheduled. The first pilots to use the facility began their training on Aug. 1, 2017, as planned.
The project team and crews will have worked 2 million man-hours upon completion, which is expected at the end of March. Fabrication shops will add another 750,000 man-hours in providing materials to the site, Cummings notes.
So far, the project has achieved a total recordable incident rate of 0.75, he says. “This is attributed to a constant focus and commitment by supervision and the tradesmen to keep themselves and others safe at all times,” Cummings says.
Adds Dorsey: “The project is right on schedule and is significantly under budget.”