This June, San Francisco International Airport (SFO) completed a $75 million taxiway reconstruction project, removing two heavily used taxiways and replacing them with two separate, non-intersecting taxiways. The updated layout improves safety and efficiency by providing pilots a better line of sight down the runway and brings the airfield up to current FAA standards. The project included full-depth taxiway construction; FAA fiber optic and runway status lighting; electrical and lighting infrastructure; relocating a fuel vault with associated valves and piping; storm drainage work; airfield signage and lighting as well as pavement marking.
The previous layout had an unconventional design with taxiways D and T intersecting with converging centerlines, which created potentially challenging conditions for planes exiting Runways 28L and 28R, SFO’s predominant arrival runways. Due to non-standard geometry and the acute angles, aircraft exiting Runway 28R onto the high-speed Taxiway T had line of sight challenges when crossing Runway 28L, Taxiway D and Taxiway K. Realigning Taxiway T to cross Runway 28L perpendicularly and eliminating the need to cross taxiways D and K improved both safety and operational efficiency by allowing the taxiways to be used simultaneously.
The previous site was identified as a potential hot spot through the FAA Runway Incursion Mitigation program in 2015, and SFO began planning the fix in 2016.
 facts&figures
Project: Taxiway Improvements Location: San Francisco Int’l Airport, in CA Cost: $75 million Funding: $39 million in FAA Airport Improvement Program grants; $36 million from capital program bonds Construction: Jan. 2024–June 2024 Key Components: New non-intersecting taxiways; relocated fuel vault & lines Construction Manager/General Contractor: Golden Gate Constructors Project Design & Construction Management: AECOM Electrical Subcontractor: Royal Electric Fuel Subcontractor: McGuire and Hester Storm Drain Subcontractor: Fontenoy Engineering Grooving: ABSL Construction Markings & Striping: Chrisp Co. Civil Design: SFO Engineering (in-house) Electrical Design: Lean Engineering Fuel Vault Design Subcontractor: Burns & McDonnell Lighted Runway Closure Marker: Sherwin Industries Key Benefits: Enhanced safety; increased efficiency; reduced delays; compliance with FAA standards; improved airport operations Of Note: No incursions or aircraft safety incidents during 6-month runway closure |
Taxiway T, one of the busiest at SFO, was last overlaid in 2006, while Taxiway D was reconstructed in the early 1990s. The recently completed project presented an opportunity not only to enhance the airfield’s geometry but also to reconstruct and rehabilitate a high-traffic area.
Changing the geometry of taxiways D and T required significant construction, including extensive excavation, drainage work, paving, striping, markings, lighting and signage. Additionally, the closure of Runway 10R-28L was necessary to reconfigure the runway entrance lights, taxiway lead-in lights, signs and other electrical systems.
The $75 million taxiway reconstruction project was funded through $39 million in FAA Airport Improvement Program grants with the remaining $36 million covered by SFO’s capital program bond funding.
Assembling the Team
Airport leaders determined a construction manager/general contractor project delivery would fit the project best and selected Golden Gate Constructors, a joint venture between Graniterock and DeSilva Gates Construction that has been doing airfield improvement projects at SFO for the last 10 years. AECOM, which has been supporting SFO airfield projects for the past 13 years, was hired for project management support.
Golden Gate worked to efficiently schedule the project with detailed coordination and input from key project stakeholders including airfield operations, FAA air traffic control, FAA tech ops, airline representatives, subcontractors, vendors and other entities. “There’s some coordination work that takes place almost on a daily basis to ensure that there are no safety impacts or any challenges,” notes Daniel Lee, airfield program manager with the SFO Design and Construction Team. “We wanted to correct those things at a moment’s notice.”
AECOM worked as an extension to the airport project management team, providing inspections, support and quality assurance testing to ensure specifications were met. The firm also acted as the primary point of contact between stakeholders, contractors and airport management, while managing logistics and ensuring that construction proceeded according to plan and remained on schedule. “AECOM’S role is fundamentally to provide the day-to-day professional services that keep the project moving forward,” comments AECOM Project Manager Mark Summers. “Our role develops and changes as the projects move from planning into design, and then through construction.”
Planning and Re-Planning
Replacing two taxiways is no small feat at an airport with more than 50 million passengers in 2023. The original plan included more of the project to be built during night work closures, which would have significantly extended the project duration because working in limited windows would have taken almost twice as long to complete. To streamline the process and reduce the overall impact of the project, the team revised the phasing strategy to schedule continuous work until the end of May; suspend work during the high passenger volume months of June, July and August; and then resume in September for the final 30-day phase.
Construction started on Jan. 18, 2024. After the project began, however, project stakeholders suggested working straight through the summer months for an earlier overall completion. So the project team collaborated with key stakeholders to make that possible. “We were all focused on delivering the job on time,” says Quinn Hennig-Hance, senior project manager for Golden Gate Constructors. “Most of the stakeholders, both on the airport side with the airlines, tenants, service contractors and vendors, as well as the construction teams were understanding of the impact of this project and to the operation of the airport and really supportive of our efforts to bring it in ahead of schedule and complete it successfully.”
Near the end of Phase One, SFO asked for an accelerated timeline for Phase Two, which was planned to take 30 days. Golden Gate Constructors fulfilled that request and completed the work on June 21, which was 10 days ahead of schedule. The company expedited construction by shifting to a 24/7 schedule, adding work on Sundays. It also doubled its onsite crews and made sure extra standby equipment and materials were readily available to minimize downtime and avoid delays. This early completion enabled the airport to increase its arrival rate, which benefited all stakeholders.
When planning the temporary closure of Runway 28L to allow construction, the SFO team carefully assessed the anticipated impact on operations, as it would dramatically reduce the rate of arrival. Personnel met with airlines to adjust the flight schedules, ensuring they aligned with the reduced capacity. Closing one of the two primary runways used for landings would limit operations, but the airlines cooperated by making voluntary schedule reductions. Even with these adjustments, the SFO team expected disruptions and forecasted delays averaging 30 to 60 minutes for about a third of flights. Actual delays closely matched that estimate during the six months Runway 28L was closed.
In addition to delays, the SFO team monitored the cancellation rate, which had previously spiked to more than 100 cancellations per day during a similar runway construction closure at the airport in 2017. However, in this instance, the cancellation rate at SFO remained below 1% throughout the runway closure. Airport and project leaders attribute this success to the proactive schedule reductions.
Project Impact
Beyond separating and realigning the two taxiways, engineers also had to relocate all associated underground infrastructure, including storm drainage, airfield lighting and signage, and FAA fiber optic and runway status lighting.
Crews pour the bottom slab for the new fuel vault, which is buried 15 feet deep.
This project realigned 850 feet of Taxiway D and 1,050 feet of Taxiway T. “The amount of pavement that we worked on for these taxiways was the equivalent of 15 football fields,” says Tiffany Ip, civil engineer with the SFO Design and Construction Team. There were more than 1,400 truck deliveries for the asphalt alone. Crews also laid more than 11 miles of electrical cabling and used more than 700 gallons of paint for taxiway and runway markings.
Another major infrastructure change—and the key factor driving the schedule of Phase One—was relocating one of the airport’s main-line fuel vaults because the new Taxiway D alignment conflicted with the existing vault’s footprint. Initially, the project was designed without relocating the fuel vault and the new Taxiway D segment, but after feedback from airline stakeholders and air traffic controllers, the redesign was completed in 2023 to include this critical task.
The former underground vault was approximately 16 by 16 feet and buried 16 feet deep. It housed three large remotely controlled valves connected to the main 24-inch fuel line that supplies fuel to the gates at the terminals. To create space needed to reconfigure the taxiways, crews had to demolish the existing vault and construct a new one 150 feet to the west. “When we were talking about relocating this vault in the planning stages, it was important to communicate to the stakeholders what exactly this scope was,” Hennig-Hance explains. “It’s not like you pick it up and move it. This is a large, cast-in-place concrete structure.” After demolishing the old fuel vault, crews built a new concrete structure that measures roughly 20 by 20 feet and is buried 15 feet deep. This work, critical for the first phase, was sequenced to be completed during the wetter winter months in early 2024 and was accomplished without disrupting aircraft fueling operations at any terminal.
Airport operations teams appreciate that the project was initiated and is now complete, Lee notes. “They know how difficult the project was and how challenging it was for everyone,” he comments. “The fact that all stakeholders were invested in the project really shows how the airport partners have a culture where we really work well with one another.”
Green Measures
Although there were not many opportunities for sustainable materials or practices during the taxiway project, SFO took advantage of those that were available. In the pavement design, engineers specified a recycled concrete aggregate base material instead of a crushed aggregate base, which is virgin rock obtained directly from a quarry.
The material used to backfill trenches and excavated areas also has environmental virtues. “We used a material called native slurry backfill, where we reused existing material and treated it with cement as opposed to importing engineered fill from the outside. That, in turn, reduced the amount of trucking as well,” Ip notes.
FAA and airfield lighting required new duct bank infrastructure.
Challenges and Solutions
One of the largest challenges in the taxiway project was simply its location. “This is one of the highest traffic operations areas, basically in the middle of our airfield,” Lee notes.
It required closing taxiways A and B, the two main arterial taxiways that encircle the terminals. In addition, Runway 28L was closed for landings and takeoffs and instead used as a detour taxiway to navigate aircraft around the work area. “All aircraft arriving or departing SFO need to travel along these two ring taxiways,” Summers explains. “Therefore, phasing the works to maintain the functional circulation of aircraft was key in allowing construction to progress but also to ensure aircraft could still navigate around the work area when taxing to and from the terminals.”
Moving aircraft around the work area required thorough planning taxiing well as cooperation from SFO, airlines, pilots and as air traffic controllers. “Strong coordination was key to our success, as it ensured there were no safety operational risks,” Lee remarks. “We had no safety incidents throughout the entire six-month period.”
Another hurdle for the project was the impact on passenger operations when Runway 28L was closed. Beginning construction in January and working to finish before the busy summer season subjected contractors to unpredictable weather conditions.
Temperatures were mild from January through March, but heavy rain in February delayed some aspects of the fuel vault construction. Fortunately, the construction manager/general contractor project delivery facilitated a collaborative response. “No matter what the impacts were, we were always looking for opportunities to recover on that schedule and deliver on time,” Hennig-Hance recalls.
Relocating the vault was a big undertaking that involved major fuel lines from more than 20 years ago. “The vault’s relocation was meticulously planned, phased and coordinated with stakeholders to ensure that its relocation went smoothly with negligible impact to aircraft fueling,” Summers says. The teams had approximately three months to complete this work, as it was an enabling project for taxiway construction.
Additionally, the scope and magnitude to clean the newly installed fuel system was broader than many on the project team had expected. As a result, the teams had to adjust plans and implement a recirculation flushing system. This required extensive coordination with the airline fuel consortium, quality representatives, subcontractors and vendors. The team quickly realized that ongoing and proactive coordination was essential. They conducted town hall meetings and daily check-ins with air traffic control and key airlines to help address issues promptly. “When you have this culture of inclusivity, these stakeholders become a part of the project team and are more inclined to help and support,” Hennig-Hance comments. “There’s more buy-in and understanding of the project.”
Yet another challenge involved coordinating the tie-in of electrical and communication infrastructure for the fuel vaults, which affected one terminal’s electrical panel. Weeks of meetings were dedicated to planning this operation, including testing battery backups and developing contingency plans. This coordination proved to be successful, as the tie-in was completed without unplanned impacts.
Although the project included challenges, the work inherently created opportunities for additional improvements. “The project is a triple-win for the airport,” Summers comments. “It not only addressed the incursion and safety concerns created by the relic geometry but also gave us an opportunity to rehabilitate high-use taxiways in the heart of the airfield that are otherwise hard to access during normal airport operational conditions; plus, the bonus of improving operational efficiency allowing aircraft to exit the runways and arrive at their assigned gates faster than before.”
Realigning taxiways D and T shifted their intersection with Runway 10R-28L and required changes to the lighting infrastructure at these intersections. Instead of creating a patchwork of conduit trenches to remove the old lighting and install new, a 4-inch overlay was applied to the entire affected area, ensuring a uniform and high-quality surface for aircraft, Summers explains.
A Learning Experience
Lee emphasizes the importance of comprehensive planning and coordination with all stakeholders. The team held monthly town hall meetings with 70+ attendees and coordinated closely with airlines, the SFO ground service group and air traffic control. Extensive communication throughout the project provided stakeholders with regular updates on progress and challenges. “Effective communication is very important,” Lee says.
The project team also prioritized safety, with extensive risk management evaluations and training for construction crews. “We put in project safety meetings as well as field safety check-ins to make sure that everyone is performing and looking out for one another,” Lee adds.
To enhance coordination, the SFO team co-located with project designers, management support teams, Golden Gate Constructors and AECOM. Working from the same office facilitated communication and collaboration, fostering a strong culture of engagement and teamwork.
AECOM, Golden Gate Constructors and SFO spent the latter part of 2023 planning and phasing the project. “The early engagement on the contractor through a progressive CMGC [construction manager/general contractor] contract meant that they were engaged and could provide early input in the design, constructability and phasing of the project,” Summers explains. “This was key to balancing construction efficiency with minimizing operational impact.”
Hennig-Hance underscores the importance of partnering with airport operations and airline representatives to minimize disruptions. During the taxiway project, detailed meetings were held regularly to discuss the timing of gate impacts, in an effort to find the most optimal schedule. “We try to be respectful of their business and do what we can to streamline our operations—to reduce the impact on those stakeholders, who we consider our partners on these projects,” Hennig-Hance comments. Early challenges, such as staffing issues during the winter months, required close collaboration with airside operations to adjust schedules and find practical solutions. Golden Gate Constructors also partnered with the engineering team to troubleshoot issues while maintaining high quality and achieving project objectives, says Hennig-Hance.
The key takeaway for Mario DaRosa, project manager with Golden Gate Constructors, was the importance of engaging all stakeholders early in the project and keeping the lines of communication open. “Engage all stakeholders very early on,” he advises. “Have open and honest communication about what the schedule is going to look like, and then try to really understand impact to the overall airfield operations, what your project is going to be, and try to seek opportunities to minimize that impact to those folks.” Ensuring that materials and resources are lined up in advance is also crucial to avoid delays and keep the project on track, he says. The taxiway project, which ran 24 hours a day, six days a week for six months, required constant problem-solving and stakeholder engagement to ensure smooth progress.
Lee says it’s critical to engage the right resources and understand how to shut down a runway, construct taxiways and manage associated tasks. Early planning and coordination are key because airlines may have specific requirements and differing opinions during the process. That’s why he worked to align everyone’s focus on the shared goal of improving taxiway alignment. “If everyone has bought in, then it’s less about what difficulties they may have during the six months of construction and more about what the end results will look like,” Lee explains. Getting that perspective is what truly matters, he emphasizes.
Coming Up at SFO
Many of the capital projects SFO put on hold during the COVID-19 pandemic are now being reactivated as passenger traffic has resumed to previous levels. The final phase of the Harvey Milk Terminal 1 has been completed, a $2.5 billion project that started in 2016. In July, work began on the Terminal 3 West modernization project to update the airport’s oldest terminal, built in 1979. This $2.6 billion modernization will take approximately four and a half years to complete.
This new fuel vault replaces a previous vault that conflicted with realigning Taxiway D.
Around $3 billion of infrastructure upgrades are also underway. They include improvements to electrical infrastructure, enhancements to the water treatment facility and upgrades to the central plant responsible for heating and cooling. These projects aim to increase efficiency and support the goal of achieving “Triple Zero”—zero carbon emissions, zero waste going to landfills and zero net energy consumption.
Finally, a shoreline protection program to safeguard critical infrastructure is currently in the permitting process. This program is designed to secure eight miles of water lines along the airport border against sea level rise, ensuring that all the ongoing work is resilient to climate change.
