Beauty scale

How Builders Made San Francisco’s Air Traffic Control Tower Earthquake Resistant

Located just 2.5 miles from the San Andreas Fault, San Francisco International Airport (SFO) is in an earthquake-prone area. In 2016, a project to rebuild its control tower between Terminals 1 and 2 was completed. It was built with greener technology and was also built to withstand 8.0 magnitude seismic events.

A combination of striking beauty and updated seismic standards, the airport control tower received numerous accolades upon its completion and is known to be one of the best in the world.

The control tower project

Beginning in June 2012, SFO and the Federal Aviation Administration (FAA) jointly launched the $150 million project. SFO would invest $69 million in it and would be responsible for integrating the tower into the existing airport structure and for the aesthetics of the tower. The FAA invested the most, at $82 million, paying for the costs of the building itself.


The primary goal of the project was to update the structure to meet current seismic standards, the FAA said. Its predecessor had been in service since 1954, but the renovation of the existing building was not considered “feasible”, so the airport decided to dismantle it and build a new one.

The building was designed by Colorado-based Fentress Architects and Kansas City-based HNTB. In the end, the structure was 220 feet tall, and the 650-square-foot controllers’ section gave air traffic controllers a 235-degree view of the airport’s runways and taxiways, the FAA explained.

Although the control tower was built to address concerns about its ability to withstand earthquakes, it was also built to attract attention. According to Fentress, the “twisted facade” is inspired by the color, massing and materials of the passenger terminal. Doug Yakel, SFO’s public information manager, also said that while the structure was designed to fit the terminals, it was also designed to be an “iconic landmark”.

The SFO Air Traffic Control Tower is designed to be an eye-catching landmark. Photo: FSO

Airport manager Ivar C. Satero said at the time of completion:

“The result is a masterpiece, filled with state-of-the-art safety engineering, cutting-edge technology and the visual vibrancy to represent SFO for decades to come. I truly appreciate the vision, dedication and the teamwork that made this exceptional facility possible.”

In addition to the control tower, the project includes a large office at its base, known as the “Integrated Facility,” Fentress said.

Alongside Fentress, HNTB was contracted as lead architect to complete the conceptual work and design the tower to 45% completion. The company said its biggest challenge was “squeezing” it into the tight space between Terminals 1 and 2.

So how can it withstand earthquakes?

The California Earthquake Authority says scientists believe the San Andreas fault line could cause a destructive California earthquake by 2030. This possibility is not exaggerated, as the fault has caused one of the largest earthquakes in California in 1906 with a scale close to 8.0, killing approximately 3,000 civilians.

While earthquakes have been the cause of major city-wide lockdowns, flight cancellations and airport disruptions, air traffic controllers are essential to keeping planes safe in the skies, even during a natural disaster.

According to Fentress, the control tower includes a “post-tensioning” system, which helps the structure not sway with extreme winds or a large earthquake. Post-tensioning is used to strengthen concrete and increase its strength by being compressed.

The airport is in an earthquake prone area. Photo: FSO

Rafael Sabelli, director and director of seismic design at engineering firm Walter P Moore, explained in Structure Magazine that post-tensioned cast iron “stands up to extreme earthquakes and wind-induced vibrations.” Sabelli also said the base building had concrete walls and a steel frame that could withstand “threats of explosion” from nearby roads. He said:

“A performance-based seismic design methodology was adopted early in the process, allowing flexibility in structural system choice and reliable, customized performance goals. Located 2.5 miles from the San Andreas Fault, the control tower is designed to remain fully operational at the Design earthquake level and to provide safe, collapse-free egress at the maximum considered earthquake level.”

Indeed, the post-stressed core is supposed to refocus in the event of an earthquake and if it then deforms the building. Sabelli said the project demonstrated the “feasibility” of building “damage-resistant, self-centering structural systems in an economical and efficient manner,” as the SFO and FAA completed it on budget and within schedule. time limit.

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Built with durability in mind

Although the control tower is known for its strength and aesthetics, it was also built with sustainability in mind. In 2011, SFO established its roots in sustainability by opening the first LEED Gold terminal. Then, in 2016, SFO created a strategic plan to achieve net zero carbon, ahead of many other national airports. As of 2021, the airport had received approximately five million blended gallons of Sustainable Aviation Fuels (SAF).

The control tower was built with solar panels and ecological materials in its mechanical and technical systems. SFO and the FAA selected Ambient Energy to help the project achieve Gold LEED certifications. The company provided energy modeling for Title 24 compliance, thermal comfort studies, and foundational and enhanced commissioning.

The company said the tower was expected to save 12% energy and 33% water. In addition, more than 75% of waste during construction was recycled.

Sources: California Earthquake Authority, FAA, SFO, Structure Magazine,