NFPA Journal®, September/October 2004
by Stephen Barlas
|Bottom front view of the 1903 Wright Flyer hanging in the Milestones of Flight Gallery at the National Air and Space Museum. Photo: Eric Long/OIPP, National Air and Space Museum, Smithsonian Institution|
|A 70-foot polished steel sculpture called Ascent, created by John Safer, relfects the Udvar-Hazy Center´s control tower, IMAX theater, and an airliner flying overhead. Photo: Craig Parham, Smithsonian Institution|
|Conducting a pump test. Photo: Capitol Sprinkler Contracting, Inc.|
Antique airplanes hang from a barrel-vaulted ceiling 10–stories high. At the far side of the museum, a second, higher walkway runs almost the entire length of the three football-fields-long structure at right angles to the lower walkway. Those two perches let observers look up and out at an amazing collection of historic planes, such as the Enola Gay and the SR-71 Blackbird, some of which had been in storage since well before the Smithsonian Institution's Air and Space Museum opened in 1980.
The Udvar-Hazy Center, the new Smithsonian aviation museum, which opened in December 2004, is built to resemble an airplane hangar—which isn't much of a design leap since its raison d être is to display the aviation artifacts that didn't fit into the Air and Space Museum in downtown Washington, D.C., 25 miles from Udvar-Hazy in Virginia.
In 1999, Udvar-Hazy, chair and CEO of International Lease Finance Corporation, pledged $60 million for the new companion facility at Dulles Airport in Virginia. At the time, it was the largest-ever contribution by an individual to the Smithsonian Institution. He later increased his pledge by $5 million.
In an architectural sense, Udvar-Hazy mimics the U.S. Air Force Aviation Museum at Wright-Patterson Air Force Base outside Dayton, Ohio. That museum features three, hangar-like structures sitting side by side, the first built in 1971 and measuring 800 square feet (74 square meters) by 240 square feet (22 square meters). However, the steel truss-construction Udvar-Hazy is considerably longer, and its square footage is one-third greater than the USAF museum's first building.
But it isn't only the size of the Udvar-Hazy that makes it unique. So do some of its other features, including a 164-foot (49-meter) glass-enclosed observation tower and a separate restoration hangar—not yet built—where planes will be worked on inside a visitor-friendly viewing area.
"This was a once-in-a-lifetime project," says John O'Neill, a partner at The Protection Engineering Group, PC. O'Neill worked on the project while at Gage-Babcock & Associates, which was hired to design the structure's fire protection systems by project architect Hellmuth, Obata, & Kassabaum (HOK).
"It is not often you have a museum, industrial space, and an IMAX theater in the same location, much less a collection of some of the most important air and space artifacts the United States has," O'Neill says.
Looking up from the Udvar-Hazy bridge at the aerial artifacts dangling like Christmas ornaments, it's easy to understand at least some of the fire protection design challenges the museum posed. Take the sprinkler system, for example. Snaking in and out of the airplanes, the interconnected piping would have looked like a crooked jungle gym.
Instead, 24 white sprinkler pipes 2 inches (5 centimeters) in diameter and 280 feet (85 meters) long run up the arched museum roof like ribs, following the contour of the ceiling. Each pipe has a 4.9-degree bend every 10.6 inches (27 centimeters). The piping feeds the branch lines, which feature 4,600 Viking pendant and upright quick-response sprinklers. The number and placement of the sprinklers was dictated by NFPA 13, Installation of Sprinkler Systems.
"This is the most unique sprinklering application I have seen in 25 years," says Vince Caponi, battalion chief and fire marshal for the Metropolitan Washington Airports Authority (MWAA).
As the first responder for the museum, MWAA had a considerable interest in making sure Udvar-Hazy was well protected and accessible. Caponi was involved in all fire protection engineering decisions, even making some key decisions on his own. For example, fire brigade access to the museum was initially planned for the back of the building, through the restoration hangar, which was the shortest distance from MWAA's fire station. Because of funding problems, however, that hangar has not yet been built.
"When funding for the restoration hangar was delayed, Vince allowed the building to be flipped, with the fire panel in the entrance of the building," says Walter Urbanek, the project manager for HOK.
The route the vintage airplanes would take to the museum raised fire protection issues of its own. Both Caponi's fire trucks and the planes flown into Dulles and then towed from there to the museum take Haul Road, which runs behind the museum. Ross Mowery, a Smithsonian fire protection engineer who was heavily involved in Udvar-Hazy's construction, says deciding whether to let the old planes motor over to the museum under their own steam or tow them was a critical issue. NFPA 403, Aircraft Rescue and Fire Fighting Services at Airports, defines the various on-airport "movement areas" and provides different crash rescue requirements for each. Aircraft moving under their own power, carrying fuel, pose a more significant risk than towed aircraft, defueled for museum display.
"Had we decided to allow the planes to move themselves, the FAA may have required us to build MWAA another fire station close by the museum," says Mowery, only half in jest. As it is, the Smithsonian leases the land for the new museum from MWAA, which used some of those lease payments to buy a new fire truck.
Of course, NFPA fire codes and standards were a big factor inside the building, too. Two open-topped, glass elevators at either end of the skywalk rise about 45 feet (14 meters) from the floor of the museum to the gleaming, black metal walkway. The roof is 55 feet (17 meters) above the elevator's highest point.
"We weren't sure what to do there," explains Craig Barham, vice president of Capitol Sprinkler, the sprinkler installer. "Under a strict reading of NFPA 13, we would have had to run sprinkler pipes either up the sides of the elevator or dropped them from the ceiling and attached the sprinklers that way."
However, NFPA 13 permits some latitude based on the number of stops an elevator makes and its height. Depending on those factors, an open-top elevator might not need sprinklers. The final decision was to forego the sprinklers.
There was also substantial discussion over the design of the sky walkway itself. The Virginia Uniform Statewide Building Code cites NFPA 101®, Life Safety Code®, on egress distances, requiring the most remote point of the building be no more than 250 feet (76 meters) from an exit. It would have been impossible to satisfy that requirement since the elevated walkway's center point is 420 feet (128 meters) from the nearest exit. To keep the panorama of the antique planes the walkway provides, Gage-Babcock applied to the state of Virginia for a variance.
The MWAA Building Codes Department granted the variance request based on fire modeling Gage-Babcock did using the fire dynamics simulator (FDS) developed by the National Institute of Standards and Technology (NIST). Gage-Babcock determined that, by the time smoke from a fire reached the hangar's ceiling, then descended to the level at which museum-goers congregated, someone standing at the mid-point of the walkway would, in fact, have time to reach an exit.
Gage-Babcock's use of the FDS at Udvar-Hazy was the first time that software was used in the field by a private fire engineering firm, according to Kevin McGrattan, a mathematician at NIST's Building and Fire Research Laboratory. It hadn't even been officially released at the time. It was still being tested in conjunction with an NFPA Research Foundation study of the interaction of sprinklers, roof vents, and draft curtains in warehouses and big-box retail stores. As part of the study, full-scale rack storage fire tests were conducted at Underwriters Laboratories in Chicago. McGrattan used the FDS to simulate the UL tests and compared the results he got to the fire test results. The favorable comparison of model and experiment convinced Gage-Babcock that the model could be used to simulate smoke movement in the new museum.
"Getting that variance was extremely important, because the length and placement of the walkway had been designed with optimal viewing of the exhibits in mind," explains O'Neill.
Gage-Babcock designed some unique fire protection solutions elsewhere, too. There is no separate audible fire alarm system in the main hangar or the space hangar, which is still under construction. Their height, concrete floors, and general acoustics would have rendered useless any fire speaker system, since they typically are not as clear or powerful as a public address system. That's why Charley Hahl, the Gage-Babcock principal-in-charge, decided to use higher-fidelity public address speakers for the fire alarm system. This move was consistent with NFPA 72®, National Fire Alarm Code®.
The fire alarm system has priority over the building's public address system announcements, and the public address system is supervised for trouble conditions that might impair its ability to sound an alarm. The fire alarm system automatically turns off exhibit audio-visual displays during alarm conditions.
The impact of foregoing a separate fire alarm speaker system is lessened by the fact that the museum has a large security force who would easily be able to locate all visitors quickly in the museum's open space.
Given the location of the museum near the busy Dulles Airport, heightened concerns about terrorism, and revelations about fireproofing coming out of the NIST investigation of the World Trade Center collapse, one would expect fireproofing to be unusually thorough. And it is.
Bruce Rosenthal, the area supervisor for Hensel Phelps, which was responsible for the fireproofing, insisted on reapplying the fireproofing throughout the public areas, including the IMAX theater, and in the observation tower whenever he felt construction activities made that necessary. There's no fireproofing in the main hangar because it is classified as a "mall" space, and intumescent fireproofing was used on the outside of the glass-enclosed viewing tower for aesthetic reasons.
Rosenthal had to be tough in order for the fireproofing to pass inspection, and the ceiling couldn't be closed up until it was done.
Construction on the tower, the IMAX theater, and the other places where fireproofing was applied is complete, but other planned parts of the museum exist only on blueprints. That is true of the restoration hangar, where aging planes will get a makeover. Jim Convery, another Gage-Babcock engineer, participated in the design of the fire protection features of that still-unbuilt facility. "We paid particular attention to NFPA 30, Flammable and Combustible Liquids Code, and NFPA 45, Fire Protection for Laboratories Using Chemicals, because of the chemicals which will be used in that room," explains Convery. "We had to classify the chemicals for NFPA 30 and, based on that classification, make decisions on things like fire-ratings for the walls, floors, and ceilings."
Unlike most industrial settings where those kinds of chemicals are used, the museum will use those hazardous materials very close to large groups of people. Moreover, the plan is to install a glass-viewing ceiling or wall so museum-goers can see the old planes being worked on.
"So the possibility of a chemical-induced explosion was one we had to investigate very closely," says Convery. Venting in particular was a major issue. Convery had to make sure that the restoration wing's dedicated air handlers were "intrinsically safe," meaning that any sparks they might produce wouldn't ignite any of the chemicals flowing through the vents.
Those kinds of fire protection concerns separate Udvar-Hazy from any other museum in the world. So do the fire engineering solutions. It is a one-of-a-kind place, and a whale of a place to visit.