Sea-Tac Airport now home to longest aerial walkway over an active taxiway

Seattle-Tacoma International Airport (SEA) made history last week by moving the huge – no, the gigantic – centerpiece of a new record-breaking pedestrian walkway from one part of the airport to another and lifting it, very, very slowly, into place.

The centerpiece is the 320-foot-long center span of the 780-foot-long walkway being built as part of a $968 million International Arrivals Facility (IAF) at Sea-Tac that will double the number of international capable gates and greatly improve the arrivals experience.

A signature feature of the project is an aerial walkway, or bridge, that stretches 780 feet across and 85 feet above an existing taxiway. When complete, the walkway will be the longest structure over an active taxiway.

Arriving international passengers will enter the steel and glass walkway from Sea-Tac's South Satellite and walk over an active taxiway as they make their way to the new arrivals facility and go through customs. As they walk, they'll be treated to views of Mount Rainier (on clear days) and the sight of planes as large as 747-400s taxiing underneath the walkway.

Moving a monster

The center span is the size of a football field and weighs 1,565 tons. Port of Seattle officials say that weight is equivalent to 14 blue whales or eight locomotives.

As you might imagine, moving this huge center span across the airport and up into place was no easy job. But between Thursday night and Saturday morning, the job was completed.

Here's how they did it

The center span of the walkway was prefabricated off-site at the airport's Cargo 2 area.

Late last Thursday night, when it was time to bring the span over to the International Arrivals Facility construction site, it was moved down the closed center runway very, very slowly – at a speed of 2 miles per hour – with the help of four remote-controlled transporters, called Self Propelled Modular Transporters.

Early Friday morning the aerial pedestrian walkway span arrived at its location between the South Satellite and Concourse A. Several hours of site checks and adjustments followed to make sure all the pieces would line up between the already-constructed piers. Then, four strand jacks began lifting the center span into place, at a rate of 20 feet per hour.

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As this unique project was underway, lucky passengers – and SEA Visitor Pass holders – were able to watch the span's progress through the windows from many spots in the concourses and from the South satellite.

The Port of Seattle also kept us up to date on Twitter and on Facebook.

Who will walk over the walkway first and when can you do it?

The new International Arrivals Facility (IAF) at Seattle-Tacoma International Airport may be open and operational by Fall 2020.

An airport spokesman said the first people (other than project testers) to walk over the bridge will likely be elected officials and commissioners. After that, only arriving international passengers on planes arriving at SEA's South Satellite will have the thrill of walking across the world's largest structure over an active taxiway.

All photos courtesy of The Port of Seattle.