It's nearly time. 71,795 screaming fans. 110-million plus global TV viewers. $5 million 30-second ads. The chance for the New England Patriots to claim their fifth Super Bowl championship, or the Atlanta Falcons their first. Lady Gaga. And yet one question remains for the structural engineering team at Houston-based Walter P Moore, which helped to build NRG Stadium, where the game will be played: Will they open the retractable roof?
“It must be a Houston thing,” said the company’s national sports market leader, Bart Miller, in advance of Super Bowl LI. “Retractable roofs aren’t entirely new but are still quite a novelty in stadium development, and yet at NRG we almost always play with the roof closed and the [air conditioning] on full blast.”
Completed in just 30 months to be ready for the 2002 NFL season, the $352 million NRG Stadium boasts more than 7,000 club seats and 196 luxury suites, and it can be configured into a 125,000-square-foot space for meetings, concerts and special events. To enhance the Texans' bid for Super Bowl LI (NRG also hosted the 2004 game), stadium owners upgraded the end zone scoreboards with two, 100-ton Mitsubishi video screens following the 2012 season, yielding 14,549 square feet of display surface in total.
With stadium builders and renovators engaged in perpetual one-upmanship to deliver the ultimate fan experience, NRG’s record-setting end zone display and retractable roof faced stiff competition even as plans for the screens were finalized. Currently under construction, the Mercedes-Benz Stadium in Atlanta and the forthcoming Los Angeles Rams stadium promise even more structural and high-tech innovations — including a first-of-its kind aperture roof for the former and a $2.5 billion construction budget for the latter.
To execute on Super Bowl–sized project expectations, builders like Walter P Moore (which has engineered eight Super Bowl stadiums since 2001) are pulling out all of the construction technology stops. To meet schedule and budget while ensuring worker safety and seamless facility operability and management post-construction, they are employing virtually every AEC tech tool available including BIM, laser scanners, drones, total stations, worker wearables and equipment tracking along with virtual reality for stakeholder communication and contractor training.
Marquee projects, marquee technology
Win or lose, the Falcons will get a Super Bowl LI glimpse of playing on the national stage under a retractable roof, although they may not recognize the similarities between NRG Stadium’s parallel rail, supertruss system and the eight-piece, pinwheel retraction roof planned for their home field. (See a video fly-through of the roof structure here.) Another Falcons stadium element tough to recognize on sight are paper construction documents for the project — because there aren’t any.
“For the scale of this project, we’re talking about 35,000 separate shop documents that are getting updated daily, multiplied by a factor of eight or nine for each crew chief working on the roof alone. To use paper documents would have been crazy,” said Parsa Sabahi, director of technology for Euless, TX-based Derr and Isbell Construction, which is leading construction of the stadium roof.
In lieu of traditional shop docs, the entire build out is being managed in an integrated software suite that includes Autodesk BIM 360 for 3-D modeling, Bluebeam Revu for document collaboration and an enterprise-built document management application for day-to-day quality assurance and safety reports, all backed up on a server as well as a Device Magic forms database. Workers can access the files from Derr and Isbell–provided iPads and view them on seven large, high-definition screens located around the job site.
Aaron White, director of digital practice at Walter P Moore, sees an integrated software suite powered by a central BIM component as the current gold standard for stadium and arena development. “You really need to manage and administer the project in a total BIM environment that includes all MEP systems. We’re working on a project now with over 70 different virtual models glued together, and the only way to handle that is in a BIM environment.”
While vendor consolidation of niche technologies promises some system streamlining, White doesn’t expect near-future stadium development and construction to ever run on a singular application. Instead, he thinks virtualization will continue to emerge as a standardized user interface for systems across design, build and facilities operation.
“I think we [will] move to a data-centric, 3-D environment in an open BIM software that expands on the current tools that are being brought to market,” White said. “Design has been forging ahead in that regard and construction is following suit. It may not be as common right now, but we expect it to grow, and we think the future of stadium construction is going to be virtual.”
Reality capture and worker tracking
Stadium roof construction, in particular, presents a clear opportunity for contractors to begin leveraging virtual reality tools. “One of the most dangerous jobs in stadium construction is when the roof comes off of [its] support towers and goes into free span,” White said. “We’d like to start using VR modeling of de-shoring the tower headers before we send workers up 150-foot towers." The use of VR could provide the team with both a look at header conditions and a simulation with access to tools in a virtual environment for training purposes.
A badge system has simplified the process of tracking worker movement for time-keeping purposes on the Mercedes-Benz Stadium. The wearables include a QR code that is scanned via iPad on ingress and egress to the job site, providing supervisors with a real-time look into man hours and personnel on hand at a given point in time.
"We think the future of stadium construction is going to be virtual.”
Aaron White
Director of digital practice, Walter P Moore
More important to the Mercedes-Benz team than wearables has been the use of daily drone flights for aerial image capture. With stadiums and sporting events still off-limits to commercial drone flights, Derr and Isbell UAV pilots had to get an FAA exemption due to the project’s proximity to the Georgia Dome. And that wasn’t the only UAV hurdle. Despite the widespread adoption of drone technology in construction, Sabahi said some members of the project team were initially skeptical regarding the usefulness of drone reality capture.
Simply putting the technology to use removes much of the trepidation from teams not yet familiar with drone capabilities. “Now we use aerial imaging for weekly reports, for comparing as-builts, and project surveyors use it for their own reports and to actualize project status,” Sabahi said. “Now, if Monday rolls around and the sky is not clear enough for a drone shot, we immediately get emails from the GC and subs looking for their missing aerials.”
White, too, sees broad application possibilities for drones in stadium construction, again pointing to safety situations where aerial imagery could provide 3rd-party inspectors access to many out-of-reach areas. White is also hopeful that point cloud data compression and transmission might lead to more regular use of laser scanning for as-built comparisons and daily project updates.
“We’ve got surveyors out there with total stations who can check project status on demand, but what are the possibilities for laser scanning during roof erection? That is an immense amount of data but worthy of considering how it might be meaningful for erectors and engineers,” White said.
Designing for weight and speed
As stadium designers continue to push the boundaries of video board display size and roof retraction mechanicals, engineers are paying careful attention to loads, environmental exposure and systems design. In 2008, Category 4 Hurricane Ike ripped several panels off NRG Stadium's roof, but the Houston Texans were able to play out the season with the roof open while repairs were made. “From Miami to Houston, we continue to look at strategies to address wing shear and pressure so roofs can be hurricane-ready and resilient,” Miller said.
While NRG's video displays are mounted against an interior wall — and didn’t need additional housing hardware when replaced in 2012 — screens at Raymond James Stadium, in Tampa, FL, are perched at the top of the cantilevered seating bowl. “Now we’re thinking about wind load and vibrations from having almost 8,000 square feet of LED wind sail attached to the building,” Miller said. “Thankfully, as technology is advancing, the screens are getting lighter per square foot.”
The aperture roof at Atlanta's Mercedes-Benz Stadium features eight retraction panels that allow the roof to open in less than seven minutes. In addition to breaking the roof up into smaller components, the use of lightweight polymers contributes to a lower weight load, particularly important as the retraction assembly sits on another portion of the roof, rather than being attached directly to the stadium superstructure. In Los Angeles, clear roof fabric will be supported by a cable system to allow for a transparent roof. Durability, rather than speed of opening, is guiding retractable roof technology for stadiums, as typical systems will cycle through about 250 openings and closing per year, Miller said.
Whether one of those 250 will occur on Super Bowl Sunday 2017 at NRG Stadium remains to be seen. Luckily for Walter P Moore and the curious at-large, there’s already a website that reports on the open/close status of retractable stadium roofs across the country. Although NRG's was TBD at press time, StadiumRoofStatus.com promises an update closer to Sunday's game. If the roof indeed comes off, it will have to be prior to pre-game warm ups, per NFL policy. So it's worth starting that Super Bowl party early.
