When it opens next May, one of the most dramatic features of the Dwight D. Eisenhower Memorial in Washington, D.C., will be a 450-foot-long stainless steel tapestry depicting the coast of Normandy, France, the site of the Allied D-Day Victory on June 6, 1944.
The 60-foot-high woven metal tapestry along the southern edge of the memorial site will serve as a striking backdrop to larger-than-life-size bronze statues depicting scenes from the life of the 34th U.S. president and five-star general.
Etched with a line drawing created by project architect Frank Gehry, the distinctive, transparent tapestry will shimmer during the day and reflect light at night, while leaving sightlines to surrounding buildings open, said Victoria Tidwell, deputy director of the Dwight D. Eisenhower Memorial Commission.
For its fabrication, by artist Tomas Osinsky, the project team used a graphic file that converted the artwork into three dimensions. In Osinsky's Los Angeles studio, weavers are using a custom-programmed CNC (computer numerical control) machine that has been modified to work with spools of stainless steel thread of different thicknesses to produce the tapestry in 604 3-foot-by-15-foot panels.
The weight of each of the panels varies based on its artwork. The lightest panels are roughly 75 pounds, while the panels with the most dense artwork weigh as much as 125 pounds. In total the tapestry will include roughly 600 miles of stainless steel cable and more than 82 million stainless steel cable welds, said Jared Oldroyd, vice president and business unit leader at Clark Construction.
Once complete this fall, the panels will be shipped to a warehouse in Maryland and then delivered in batches as installation progresses. They will be affixed to a 125-ton box beam and tensioned cable net support system anchored to six 80-foot-tall limestone columns equipped with precisely embedded plates to hold the cables, according to Oldroyd.
The margin of error for installation of the artwork onto the 24 embeds and 72 corresponding brackets is miniscule, said Brian Krause, Clark vice president and director of virtual design and construction.
To help meet the exacting requirements, Clark engineers turned to laser scanning, a technology they have used on dozens of projects across the D.C. metro area. Clark's VDC team used Faro scanners to take about 25 overlapping virtual scans of the site. Each scan took about five minutes to make, said Krause, adding that the process was similar to the digital 3D scans being used to help reconstruct the Notre Dame Cathedral in Paris.
The Eisenhower Memorial scans were compiled into a point cloud, an image that looks like a 3D model but is actually a rendering of millions of individual points, Krause said. His team then overlayed the design model with a rendering of the tapestry to gauge the precise placement of each embedded plate. To create the virtual model and point cloud, the team used a range of computer programs from Faro, Leica, Autodesk, Synchro Software and SketchUp.
Crews recently erected the columns, and, using data from the scans, affixed the embeds in the proper positions. Once the tapestry is delivered, the scans will also be used to provide exact measurements for tensioning of the cables to determine exactly how much tension should be placed on each cable when installing the tapestry.
Krause said that while reality-capture technology will help cut down the time it takes to install the tapestry, that’s not the main goal.
“It’s more about having the precision and certainty of what we’re building as we’re building it,” said Krause.
The design of the tapestry, columns and cable system will keep it secure in any kind of weather, Krause added. The team tested a full-size mockup of the installation at an Intertek testing site in York, Pennsylvania, where technicians ran it through hurricane-force winds and shot a 2x4 piece of lumber at it with no negative effects.
Clark, which also helped build two other new Washington, D.C., attractions — the Smithsonian’s $540 million National Museum of African American History and Culture and the $500 million Museum of the Bible — is using laser scanning on about 30 active projects for everything from documentation of historical buildings to identifying design risks for renovations, Krause said.
Clark's VDC team also used reality capture technology to help with landscaping at the memorial, traveling to tree farms in Pennsylvania and New Jersey to scan four large specimen trees that will soon be placed on site. Forty-foot-high Bur oaks and Columbia Planetrees with trunks as large as 20 inches in diameter will play an important role in the overall landscape plan, and knowing just how and where to place them will be helpful when they arrive on site, Krause said.
“Knowing the exact location of the branches, we can have the architect position them in the model and we can see where the cranes should come in to pick them up before we plant them,” he said.
Construction of the memorial on a 4-acre site adjacent to the Smithsonian National Air and Space Museum is expected to cost $115 million, Tidwell said, and the opening is scheduled for May 8, 2020, the 75th anniversary of Victory in Europe Day. In addition to the tapestry and sculptures, it will include an inscription wall and a 2,400-square-foot information center with a bookstore and public restrooms. (Click here for real time and time-lapse video of the memorial’s construction.)
Designed by a joint venture between Gehry Partners and AECOM, the memorial has been in progress for many years, and was stalled briefly when members of Eisenhower’s family came out against an earlier plan for the tapestry. Previously, three large-scale tapestries were proposed to frame the site on the south, east, and west sides. The final design for a single tapestry respects the site’s historic context while creating a sense of a memorial within a park, according to the National Capital Planning Commission.
Other noteworthy construction features of the memorial will include:
- The columns holding the tapestry will be covered in 4,000 pieces of Ambar Limestone being cut on a CNC machine. Each stone takes 12 hours to be cut, and the process has been underway for one and a half years.
- The inscription walls will encompass 4,000 letters carved on-site by artists who can complete about 20 letters per day. Handcarving gives more texture than a CNC lettering, said Krause.
- A 400-foot-long stormwater cistern will collect rainwater and store rainwater for use in the toilets and irrigation.