Aerial rendering of the Seattle-Tacoma International Arrivals Facility; Aerial rendering of the Seattle-Tacoma International Arrivals Facility;

Seattle Tacoma International Airport, International Arrivals Facility, Seattle, Washington

New facility uses innovative technology to double international flight capacity

Seattle-Tacoma International Airport (SeaTac) has seen a dramatic increase in international flights. As a result, the airport is experiencing a shortage of international arrival-capable aircraft gates and the existing customs area is beyond capacity. The Port of Seattle assembled a design team to create a high-quality passenger experience and advance the Seattle area as a travel gateway.

With SOM, Clark Construction, and other team members, we developed a plan to support a doubling of the airport’s international flights and destinations in the next 25 years. 

The efficiency and design of this secure facility will allow the airport to serve an increased number of international flights and passengers each day — capacity will increase to serve up to 2,600 people per hour. Arup is providing airside planning, terminal planning, and building engineering design, among other services, as part of a collaborative design-build team for the Port of Seattle.

To meet demand, the new facility will increase the number of gates capable of serving international wide-body aircraft from 12 to 20, as well as increasing the number of passport check booths and baggage claim carousels. The new design also creates a single baggage claim process, offers direct access to ground transportation, and will reduce passenger connection times from 90 to 75 minutes. 

Project Summary


450,000ft² facility

60%increased passenger capacity

2020scheduled opening

Mitigating mechanical challenges

The Arup team designed HVAC systems for a wide variety of spaces in the facility, including baggage handling, baggage claim and pedestrian walkways, as well as office, lab, and fitness areas. We addressed several challenges in the design, such as mitigating hydrocarbon odours from the airfield, maintaining positive pressurisation, designing for active smoke control, and working around massive baggage handling systems. 

To achieve optimal outcomes, we performed computational fluid dynamic analysis to verify comfort conditions in the extremely tall baggage claim areas as well as other spaces with unusual air distribution criteria. We also conducted timed egress analyses for an active smoke control system for the pedestrian walkway as well as for the open areas of the main international arrivals buildings.

The team used a multidisciplinary BIM approach to coordinate the routing of building services through extremely tight spaces in the pedestrian walkway. Our work at the arrivals facility is currently one of our highest delivering projects with a BIM Maturity Score of 82%.

Rendering of the Seattle-Tacoma International Arrivals Facility Rendering of the Seattle-Tacoma International Arrivals Facility

The new international arrivals facility (IAF) will be a multilevel facility located east of SeaTac's current Concourse A.

Customs and border protection

A new customs and border protection (CBP) processing area, which will be run in partnership with US CBP headquarters in Washington DC, will be the first to use the “automated primary” approach. This innovation allows for faster processing of passengers, shorter passenger queuing times, and improved utilisation of CBP officers. We led the effort in determining facility requirements for this advanced approach and developed detailed passenger simulation models to facilitate airport, airline, and agency review.

Reducing water demand

Our plumbing engineering services are helping the Port realise long-term aspirations of using reclaimed water to reduce their potable water footprint. A recycled water piping system was implemented to all non-potable fixtures, and the Port agreed to utilise low-flow plumbing fixtures going forward. The team also conducted a highly detailed rainwater analysis of the complex curved roof structure, which is roughly 200,000ft2, to determine gutter and rain leader sizing. 

While the building does not include any rainwater harvesting, it is ready to accept a supply of recycled water piping during the building’s lifetime, with no service downtime or necessary work. The harvesting and treatment system would be located on site at the airport and supplied to all future buildings, reducing the overall demand for potable water by the Port.

Announcements you can hear

The IAF’s terminal-wide voice and visual paging systems (TWVPS) are another feature of the innovative design. The system includes public address and visual paging coverage for all public areas in the airport expansion, as well as voice paging for office and support spaces for the customs and border protection areas.

Utilising 3D modelling and simulations, our team verified the design would meet the stringent standards set by the Port of Seattle and allowed stakeholders to hear the simulated performance of the TWVPS from various locations within arrivals. To provide even and intelligible coverage throughout the large, open-volume arrivals hall, we designed a system of digitally steerable phase-array loudspeakers, which allow passengers to clearly hear announcements and reduce the build-up of reverberant sound that can muddy speech. Working with SOM, the loudspeakers are seamlessly integrated into the impressive architecture of the new facility.