At 221 feet tall, the new air traffic control tower at San Francisco International (SFO) was designed to be functional and create a new visual landmark. Occupying prime real estate between terminals 1 and 2, the tower features nearly 150 vertical feet of glass and an LED light array to provide the iconic look that airport officials desired. At the same time, the tower and base building incorporate sustainability features and cutting-edge seismic technology designed to meet the needs of the airport and FAA well into future.
Construction of the new tower began in June 2012, and the facility went into service mid-October 2016. "We wanted to make sure it was a tower that was functional for the FAA, and that they can operate effectively for the next generation," says SFO Project Manager Mark Costanzo.
Concurrently, it was important that the structure fit with the architecture of existing airport buildings. "We worked hard to make the tower a landmark structure that would be a beacon and an icon for San Francisco for years to come," he explains.
Not only is the design of the new tower noteworthy, the process used to create it is significant as well. This was the first time FAA granted an airport the authority to design and construct an air traffic control tower.
Project: Air Traffic Control Tower
Location: San Francisco Int'l Airport
Associated Elements: Base building & pedestrian connectors
Tower Owner/Occupant: FAA
Cost to Airport: $60 million (design & construction of terminal connectors, tower façade, LED light array)
Cost to FAA: $80 million (design & construction of tower)
Design Architect: HNTB
Architect of Record: Fentress Architects
Mechanical, Electrical, Civil Designer: AECOM
Structural Designer: Walter P. Moore
Construction: Hensel Phelps
Industry First: FAA allowed airport to design & build the tower
Noteworthy Design Elements: 147-foot glass panel on tower facade; color-changing LED light array; tallest vertical post-tensioned concrete structure in the U.S.; seismic system that allows building to sway up to 6 ft. during earthquakes; tuned mass damper system to building & reduce movement in cab; pedestrian walkways that connect terminals & allow visitors to view tower through glass ceiling
Ian Gregor, public affairs manager for FAA's Pacific Division, explains that most control towers are stand-alone projects that the FAA designs and supervises; but SFO's tower project had unique circumstances that led the agency to agree to a different method. "The SFO tower project is unique in that it was being integrated into the existing terminal structure, which the airport owns and maintains," explains Gregor. "Additionally, portions of the base building serve as passenger conduits between terminals 1 and 2. Finally, the design required approval by the city's Civic Design Commission, and airport personnel are more familiar than FAA engineers with its requirements and preferences."
SFO's striking new facility replaces its former tower, which operated atop of Terminal 2 and sustained damages during the 1989 Loma Prieta earthquake that left its structural system not "up to par," explains Costanzo. After researching various options, FAA and SFO officials determined that retrofitting the damaged tower would be too expensive and decided to build new.
A siting study that considered the entire airport property identified Courtyard 2, between terminals 1 and 2, as the ideal location for the new tower. While many airports prefer to locate their towers far from the terminal areas, the best location for SFO's new tower was "smack in the middle of all the terminals," explains SFO Public Information Officer Doug Yakel, because the airport is so space-constrained. Although SFO serves more than 50 million passengers annually, it only has about 2,200 acres of developed land, he notes.
In a similar vein, most control towers at U.S. airports are strictly utilitarian-focusing on function rather than design. But SFO wanted its new air traffic control facility to excel on both fronts. "Knowing that the tower would be situated in the midst of all of these facilities we've been working so hard to renovate, we really wanted something that would not only meet the functional needs of the FAA, but meet our own design aesthetics," Yakel remarks.
The International Terminal has served as the airport's "public face" since it opened in 2000, he continues. "We viewed this new tower as an opportunity to establish a landmark at our airport that would really come to signify SFO to our region and hopefully to travelers around the world."
The airport hired HNTB as the master architect for its Terminal 1 redevelopment program, as well as the adjacent control tower and integrated facility (the base building below the control tower). The firm developed a 45% design document, which was then completed by Fentress Architects, explains HNTB Project Manager Paul Kim. Hensel Phelps provided construction management oversight.
Kim says airport officials were looking for an elegant and graceful tower design, rather than "just a lollipop on a stick" as is often the case.
The finishes and materials specified for the three-story base building and 221-foot tower feature a neutral color palette to help tie the two terminals together. Responding to the airport's desire for an iconic building, designers adorned the landside façade with a special glazing system, a glass panel that stretches nearly 150 feet tall and an LED light array.
During the day, the glass reflects sunlight; at night, it is illuminated by programmable, color-changing LED lights. The airport can show its support for various sports teams, holidays and special events by displaying the appropriate colors. "It's a really neat system and it shows how beautiful the building is when you see those lights," Costanzo notes.
"This is a new symbol for the airport and a real beacon-not so much for airplanes as it is for the public to see and know San Francisco Airport," adds Curt Fentress, president and CEO of Fentress Architects. "It's very dramatic, somewhat futuristic, and it's a refreshing piece of architecture." The overall form is reminiscent of the torches that used to guide ships into San Francisco, he continues. "It's a real landmark for the airport."
Inside the Tower
SFO's former tower, which was built in the '70s and began operating in 1983, had deficits beyond its seismic shortcomings toward the end of its life. Elements such as narrow hallways and the need to take two separate elevators to reach the cab also dated the facility.
The new tower features wide stairways and two exit stairwells from the cab for evacuation purposes. In addition, the FAA outfitted it with upgraded electronic and technological systems. The 650-square-foot cab provides controllers with more workspace and a 235-degree unobstructed view of the airfield. An offset cab allows for better sightlines and an improved operating layout. Moving vertical circulation components out of the middle of the cab allowed for more efficient use of the facility's limited space, Kim remarks.
FAA officials note that new air traffic control equipment in the controller work area includes a state-of-the-art ground radar system and touch-screen displays for weather and airfield status information. By the end of the year, the ground radar will link to SFO's runway status lights, which tell pilots when it is unsafe to enter a runway or to take off.
"It's built to last and carry us into the future," Costanzo reflects. "Where the previous one we just barely had enough to keep it operational."
At the base of the tower is a three-story, 44,000-square-foot building with FAA offices, computer equipment and a backup generator. The base building also includes walkways that connect terminals 1 and 2, pre- and post-security. The pre-security walkway offers a view of the tower above through a glass roof. "It gives the public the opportunity to enjoy the tower, even if they're not going inside of it," Yakel notes.
Seismic & Sustainability Standards
Ensuring that the new facility could withstand extreme seismic activity in the future was a high priority for the airport and the FAA. The tower employs a vertical post-tensioned system, with steel cables imbedded in the core to provide additional strength. The structure is designed to allow the tower to remain upright and fully operational after an earthquake, explains Kim.
"It's performance-based, where it can sway up to 6 feet at the top level," Costanzo adds. The cutting-edge system enables the tower to meet current seismic standards-up to an 8.0 earthquake-and is the tallest vertical post-tensioned concrete structure in the United States.
Fentress says the use of vertically post-tensioned cables is a unique, economical solution that provides high performance.
"Mucky clay" soil at the building site provided extra design challenges, he adds. To mitigate the risk of liquefaction after an earthquake, engineers added a large base slab to the foundation. If liquid rises from underneath the building, the
slab displaces the soil to prevent the building from swaying or settling.
For the comfort of controllers and other building occupants, the structure includes a tuned mass damper system that balances the building and reduces movement-and thus motion sickness-at the top. Giant 35,000-pound weights outfitted with springs are positioned on all four sides of the tower to counteract wind and slow any movement of the structure so the cab operators do not feel motion, explains Costanzo.
As with all construction projects at SFO, environmental sustainability played a major role in the design of the new tower, Yakel says. In recognition of such efforts, the project achieved gold certification in Leadership in Energy and Environmental Design from the U.S. Green Building Council.
Elements that contribute to the facility's eco-performance include: photovoltaic panels; leveraging natural daylight in the offices and public lobby; a roof garden; low-flow plumbing fixtures; energy-efficient heating, ventilation and cooling systems; programmable LED lighting; charging stations for electric vehicles; and the use of sustainably produced interior finish materials.
Success of the project relied heavily on partnership among SFO, FAA and a host of contractors and consultants, Costanzo notes. Formal partnering sessions, held monthly, brought all team members together to discuss progress and successes. They also provided a forum for participants to raise problems before they became major issues that would cost time and money.
The project demonstrates "the importance of being flexible, letting go of egos and adapting to working closely with an outside agency on a project that benefits us both," reflects Gregor.
Funding was also a partnership: FAA funded the tower portion, for about $80 million. SFO contributed $60 million for the building's façade, exterior LED light array and pedestrian connectors between terminals 1 and 2.
Because the tower was erected between the two busy terminals, the airport routed landside passengers out of Terminal 2, onto a sidewalk and then into Terminal 1 to ensure safety during construction, Costanzo reports. Keeping signage current and accurate was critical for reducing confusion; but the airport also added windows into the jobsite so travelers could watch as construction progressed.
The procurement method on the project was a learning curve for FAA, Costanzo notes. While SFO has found "tremendous success" with the design-build method, it's not a process the FAA typically uses. "This was something new for the FAA," he comments.
To ensure comfort with the process, one of the agency's resident engineers served on SFO's construction management team and was involved with every decision, Costanzo relates. While the airport oversaw the project, SFO wanted to fully include FAA throughout the process. "They inherit this building, and they're going to be operating out of it," he explains. "We wanted to make sure they were happy with everything they got."
As to whether FAA will consider this arrangement at other airports, Gregor says the agency is "flexible...and would adopt the method that best suits the individual circumstances."
Costanzo predicts the strategy will become more common: "I think based on the success of this, you're going to see this type of approach taken at other airports around the U.S."
Demolition of SFO's old control tower is expected to begin early January 2017 and last about six months.