Even Engineers Marvel Over the Curves of PDX’s New Roof

Published November 16, 2021

(Video credit: Alberta Poon)

Once the airport's nine-acre roof slides into place over the main terminal next year, what you see may depend on who you are.

You, we hope: a roofline you’ll recognize from a distance, with swooping wooden curves and giant round skylights.

Every architect, contractor, construction worker, and fabricator who built the roof: a brain-twisting feat of design and engineering.

After all, the roof's arched 80-foot-long ribs, made out of glue-laminated (glulam) wood, didn’t grow in that shape. The two-inch-thick plywood that covers those beams didn’t bend easily. It took hundreds of people and a full-scale test run just to figure out how to make the curves, well, curvy.

Zip-O Laminators, a 76-year-old family business based in Eugene, had to build a test beam merely to see if a one-piece, 80-foot arch would even fit in their plant, let alone their equipment. They used steel templates to make sure they shaped each beam correctly, pressed the glued boards together until they adhered, and carved the smooth curves by hand. Then they did it again — 272 times.

Covering the arcing beams

Next challenge: Connecting hundreds of thick, flat plywood panels together — without any gaps — to form domes and vaults that curve in three dimensions at the same time. Swinerton, which tackles construction logistics for this project, worked with CadMakers to use cutting-edge 3D-modeling software to calculate the shape of each panel and the angles at which it should be cut.

Another Swinerton partner, Freres, used a sophisticated computer-guided saw to cut the plywood, labeling each piece so the panels could be assembled on site like a jigsaw puzzle. (Sadly, they didn't scramble the pieces around just to make the puzzle more fun.)

Building the roof on site

Construction lead Hoffman Skanska Joint Venture are currently building the roof on the pre-fabrication site. Then they'll separate the roof into 18 cassettes to maneuver into place.

One other cool detail? Every major part of the roof was fabricated within 300 miles of here. The steel was milled locally. The metal girders and Y-shaped beams were fabricated in Oregon and Washington. We know the forests that supplied every one of the 35,000 boards in the ceiling lattice. (Let us introduce you to four of these sustainably managed forests and their caretakers.) The pandemic may have interrupted global supply chains and slowed construction jobs all over the world — but PDX Next has largely stayed on schedule because all our materials come from so close to here.

Jared Revay, senior project manager at Swinerton, says, "What I'd want people who see the roof to know is that all the people who made this happen — our craftspeople, our manufacturers, our vendors who stained it, even the trucking companies — everyone was so involved and so enthusiastic about this process. Without that cooperation, the success of a project like this would be very difficult."

Finishing the Roof Construction

For the past year, we've built a nine-acre roof on a prefabrication lot to the northwest of the airport. The construction crews are now installing the last component—an intricate wood lattice, sourced from sustainable Northwest forests, that will eventually cover the interior ceiling.

What you'll see: If you drive along Marine Boulevard, you can glimpse the roof's dramatic swoops in the prefab lot.

Demolishing the Last of the Clocktower Plaza

Spring and early summer

Behind all those partitions in the pre-security area, construction crews have been hollowing out the back half of the main terminal. Starting in March, the exterior structure is also coming down to create a more open, spacious footprint. It may get noisy for a few months!

What you'll see: Not much, in fact. But when you’re in the ticket lobby and going through security, you may hear and feel what’s happening on the other side of those partitions. We're strategizing ways to counteract the sound, including free earplugs at the front doors and a sensory room in Concourse D.

Installing the Y Columns

Summer

Next, we’re erecting 34 giant steel Y-shaped columns to hold up the roof. Right now, construction crews are driving steel pilings deep into the ground to anchor these columns. Over the course of a few months, we’ll erect the Y columns one by one.

What you'll see: You probably won't notice—most are going up overnight behind the temporary walls. Late-night travelers will occasionally have to walk a few yards around an installation site.

Moving the Roof Into Place

Mid-Summer Through Early Fall

Once the biggest section of the wood roof is fully assembled, the project team will break it back down into 20 "cassettes". During the summer and fall, Hoffman-Skanska and Mammoet will maneuver each cassette into place over the existing roof. It will take several days to place each cassette, and the work will happen overnight — depending on the section we’re placing, we may guide late-night travelers around a short detour.

What you'll see: Unless you're flying into PDX on a late-night flight, or camped out on Marine Drive at 2 a.m., you won't see much. If you walk to the ends of Concourse C or Concourse D and look back toward the main terminal, you'll catch a glimpse of the airport's new roofline.

Adding More of What We Love

Bonuses

In addition to the big projects, you’ll see a host of new amenities appear throughout the airport. A new play area in Concourse E. New art. New restaurants and cafes. (Lardo! Screen Door! Good Coffee!) You're almost guaranteed to encounter something new every time you visit the airport — and we're not talking barricades.