Transformative Upgrades: Elevating Seattle Tacoma International Airport's Critical Infrastructure

Airports are more than waypoints between destinations. They are significant drivers of economic growth for the United States, and each hub plays a vital role in supporting various industries. These transportation hubs are responsible for $1.7 trillion in annual economic output, according to Airports Council International's 2023 Annual World Airport Traffic Dataset report.

In the Pacific Northwest region, the Port of Seattle's Seattle-Tacoma International Airport (Sea-Tac) serves as a primary gateway, supporting over 33 airlines with an increasing traffic volume of 45.9 million visitors just last year. Initially constructed in the late 1940s, it has seen its share of expansion and growth in recent decades. In the past few years alone, several projects have targeted renovations and expansions for passenger needs, such as the modernized North Terminal.

But an airport of Sea-Tac's significance requires non-stop operation, which means ongoing behind-the-scenes upgrades that improve the functionality of critical infrastructure pieces. At Sea-Tac, U.S. top-20 builder and engineering services provider Mortenson has made substantial progress in the airport's efforts to upgrade and revitalize much of their infrastructure. From emergency power supply sources and telecommunications hubs to low-voltage upgrades, these critical infrastructure projects ensure uninterrupted functionality and longevity for the facility's future.

Alternative Utility Facility (AUF): Preventing Airport Disruption

An early effort in the airport's journey towards improved infrastructure is the Alternative Utility Facility or AUF. Focused on increasing the airport's reliability in case of a utility failure, the AUF takes over the 115kv feed that would catastrophically impact airport operations. With design mimicking the functionality of a data center, Mortenson leveraged their experience to create a future-proof facility that can evolve with the airport's growth.

Navigating through an operational airport poses its challenges. Close collaboration with airport authorities and a deep understanding of airside and landside dynamics ultimately landed the project adjacent to the

South Main Substation. The AUF's strategic location minimizes interference with existing operations while ensuring swift emergency access.

Located just a few hundred feet from a nearby jet fuel farm, the AUF hosts dual-fuel generators capable of running on traditional diesel and jet fuel. It incorporates facilities that allow for 24/7 occupancy, including a full bathroom. With continuous or near-continuous uptime, the system provides 30 megawatts of continuous power over 10 3 MW generators, and an automatic transfer switch provides a reliable source between the primary and alternate power sources.

Disruption avoidance is paramount, given that Sea-Tac operates 24/7. To ensure a switch to alternative power would work in the event of an incident, Mortenson performed a successful closed transition for testing. Sea-Tac maintains annual testing, where they drop utilities, and the generators kick in to fully operate the facility for around an hour before transitioning back to primary power. Due to the project's success, passengers and personnel are unaware when these switches occur.

Having future-proofed the facility, the Port was able to recently upgrade all breakers and allow for power transitions to happen seamlessly with just the push of a button. Supervisory Control and Data Acquisition (SCADA) systems monitor, control, and analyze the AUF equipment, providing a universal means of access to control modules.

Meet Me Room: Rising to Evolving Telecommunication Demands

In the digital age, airports are not just physical connectors; they are digital hubs that demand robust networking capabilities. Similar to the AUF, the Meet Me Room at Sea-Tac is a crucial element of the airport's next generation and future of communications. The new building serves as a demarcation point: a dividing line between where telecommunications carriers come into a centralized location at the airport and where the Port of Seattle's management and control continues.

Delivered using the design-build methodology, the Meet Me Room will route all primary services from data service providers through one centralized hub, organizing many strategies and pathways over several decades of Sea-Tac's lifespan.

A few crucial transitions are central to creating this new backbone telecommunications infrastructure. As technology evolves, tremendous amounts of copper lines are left behind and unutilized. Research indicates that some deadened copper lines were still incurring a cost for airlines despite the lack of use for over a decade. With a universal upgrade to fiber occurring in tandem with this project, the Port will take ownership of managing all internal wiring moving forward instead of individual tenants. The project is currently under construction with an anticipated completion of June 2024.

Concourse and Main Terminal Low Voltage Upgrades: Strategic Approach for Infrastructure Longevity

When we read telecom, emergency power, and low voltage, it doesn't historically correlate with terminology such as "critical infrastructure." Mortenson is not simply running new CAT 5 cables and installing phone jacks. At the airport, low voltage translates to—and is responsible for—operating everything at 480 volts or under. That includes Sea-Tac's lighting, access control systems, baggage claim systems, escalators, elevators, and even the airport's underground transit train, which connects passengers through the terminal minute-by-minute.

Now underway, SeaTac's Concourse Low Voltage and Main Terminal low voltage projects combined incur a 24-month design phase process with 42 months of construction. The first 18-24 months of that nearly four-year construction schedule involves installing and energizing the new infrastructure. Our team will spend the second half of the construction timeline decommissioning the previous infrastructure and performing cutovers.

Mortenson will perform a strategic series of over 1,200 shutdowns throughout the project—each ranging between four days to a week in total. Significant research of circuit locations established a baseline plan for organizing these shutdowns. Three crews rotate in and out via a staggered schedule, mainly between midnight and 4:00 a.m., maintaining functionality throughout the shutdown and positioning for the next one. With the system impacting every facet of the airport's operations, shutdowns are scheduled well in advance, including significant coordination among impacted tenants and staff.

Working on such upgrades in an older facility like Sea-Tac poses unique challenges and requires a multi-faceted approach. Unlike working on a greenfield site, Mortenson spent extensive time unraveling the complexities of what existed at the airport through decades of previous construction, utility installations, and modifications. The need for comprehensive records and up-to-date, as-built documentation is akin to solving a historical construction puzzle. An extensive validation phase involving 3D laser-scanning efficiently generated a composite model required for the team to understand existing conditions and determine routing. In place of a two-dimensional survey, our team assimilated all the 3D point clouds to create a coordinated set of drawings that set a precedent for future work.

Upgrading low-voltage systems might not grab headlines. Still, it is a deliberate puzzle-solving exercise that will ultimately advance and modernize the airport for the next 50 years with code-compliant panels and systems that ensure survivability and longevity. The emergency system will also be upgraded and separated between standby power and emergency. Two-hour rated cables and updated panels ensure increased survivability, and the project accounts for increased capacity demands for future airport growth needs.

The key here is not just the technical expertise—but the ability to adapt and improvise. Due diligence and a phased approach ensure that each upgrade occurs seamlessly without causing a ripple effect of disruptions to airport staff and travelers. Both low voltage upgrade projects are anticipated to finish in 2026.

Critical Infrastructure Development: Bringing Innovation and Adaptability

Mortenson's work on Sea-Tac's Alternative Utility Facility, the Meet Me Room, and the Concourse and Main Terminal Low Voltage upgrades is a new narrative of innovation and adaptability in critical infrastructure development.

The challenges faced in these projects—disruption avoidance, 24/7 operation maintenance, synchronization with other projects, and dealing with the complexities of an older facility—are not unique to Sea-Tac. They represent airports' challenges as they strive to modernize and adapt to a growing aviation landscape. Close collaboration with airport authorities, extensive due diligence, and prior planning for disruption is essential to advancing and modernizing an airport's critical infrastructure efficiently for the facility's future.


Tyson Wagner is a Senior Electrical Superintendent at Mortenson, based in Seattle, Washington. With over 25 years of electrical industry expertise, Tyson is enjoys solving complex project challenges, utilizing innovative technologies to improve the way we build. He sees immense value in early project integration, utilizing input from the design phase and closely collaborating with project stakeholders to create successful project outcomes. He is currently translating his experience to Sea-Tac where he oversees the gambit of projects Mortenson is undertaking - from the Concourse and Low Voltage Upgrades to the Meet Me Room and soon to be PF Chang’s in the North Terminal. You can reach him by email or phone at 925.595.6109 or [email protected].

Danny Keim is a Project Executive at Mortenson, based in Seattle, Washington. In Danny’s over 20-year career with Mortenson, he has led several major renovation, infrastructure, and highly complex campus expansion projects in the Pacific Northwest. With a strong background in early-engagement delivery models such as Design-Build and GCCM, Danny stays involved from pre-construction to project closeout. Danny is serving as the Project Executive for all of Mortenson’s Port of Seattle work, collaborating directly with Tyson Wagner and the project teams to create successful project outcomes that mitigate disruption for Sea-Tac’s staff and visitors. You can reach him by email or phone at 425-497-7085 or [email protected].