Portland airport crafts wooden roof, part of $2B expansion
The crown jewel of the Portland International Airport's massive $2 billion expansion is the upcoming mass timber roof for the main terminal.
The undulating edge of the roof will become the cursive signature of the airport, if not the whole city. The TCORE, or Terminal Core Redevelopment project, will see the main terminal transformed into one giant space with picture windows and round skylights, filled with live plants and a ceiling decorated with a lattice of woodwork.
The new terminal roof is being assembled right now, just across the airfield.
It will be taken apart and installed in pieces in summer 2022 while the airport operates beneath it.
On a tour of the construction site on Oct. 20, the scale of the new building became apparent. While the steel girders to which the glue-laminated (glulam) beams are connected are now only 13 feet off the ground, the 392,000 square foot roof will peak at 54 feet high when installed. The massive structure is built in 20 modules or "cassettes" that fit together like slices of bread, each 120 feet by 110 feet.
The glulam beams were manufactured in Eugene by Zip-O Laminators. The beams toward the edges of the structure have a scallop shape cut in them, but the lines of the planks are relatively straight. The roof, however, bulges in the middle to a dome shape. There, the lines on the glulam beams have a considerable curve to them, where the packed-together strips of wood have been bent into shape.
For computer numerical control (CNC) profiling, the beams went from Eugene to Timberlab, a Swinerton company in Portland, for computer numerical control (CNC) profiling. This means robotic routers were used to shape the edges of the beams and drill holes for the metal connectors that attach the glulam beams to the steel structure. The Hoffman-Skanska Joint Venture is the general contractor.
Swinerton, specializes in mass timber, including glulam timber beams and cross-laminated timber panels and members. Swinerton did the wooden structure of the First Tech Federal Credit Union in Beaverton in 2018 and Harder Mechanical on Martin Luther King Jr. Boulevard at Northeast Thompson Street in 2021.
The roof is being assembled in two places. One consists of 16 modules, the other four. On a tour of the sixteen-module site, Hoffman-Skanska project manager Katrina Day revealed that the mechanical work would be completed and then disassembled for the move. This means every piece of electrical conduit and every sprinkler pipe will be in place — as well as the insulation and finishes — before being disconnected while the structure is rolled, in pieces, across the tarmac to the terminal area.
Vince Granato, the Chief Projects Officer at Port of Portland, explained that this is just one of five projects that make up the airport expansion, which should be done by 2025.
"We're really bringing the airport into the future," he said, standing beneath a skylight. The goal is to make a larger, more navigable terminal that is seismically stable, ready for the giant earthquake that is overdue.
"Some airports have the luxury of building a new airport, but we don't have the space for that," he said. The Port of Portland chose the modular building method. The work on the new roof is being done on the west side, near the Ground Run Up enclosure, a kind of giant booth in which jets can rev their engines on the ground to test them without causing too much ruckus.
"We had to come up with a creative way to do this, and it's much safer," he said. Not only are the workers in less danger because they are working at a lower height, they are also away from all the hassles of an airport, including vehicles and passengers.
As part of architect ZGF's design, the space between the beams will be covered first with acoustic baffles (large, flat plates) and then by a lattice of Doug Fir three-by-sixes. This fairly hefty lumber will look like matchsticks from far below. Other wooden detailing around the huge skylights will give the feeling of being inside a game of pick-up sticks.
But all this must be assembled and then moved across the tarmac. The problem with modular building is always how to move the finished product into place since it is too big for most transportation systems. So, starting in March 2022, the steel beams of the new airport roof will be jacked up on self-propelled modular transporters (SPMTs), which are like giant truck beds with lots of wheels. Six bogies will be used, each with 24 wheels and rated to lift 1 million pounds. SPMTs are used to move oil rigs. Mammoet, the Dutch firm doing the job at the airport, also installed a moveable confinement shelter, bigger than Paris's Notre Dame cathedral, over the Chernobyl nuclear power station in 2016.
The Portland airport cassettes weigh only around a million pounds each. They will be moved one at a time. Synchronized jacks will keep them from having too bumpy a ride, although the wood is designed to flex in an earthquake. Trucks on the project site fly the orange and white checkered flag for airfield safety, required of anything near an airport runway.
Seventy percent of the latticework will be installed before the roof is moved, the rest added later while in place since workers have to work around the wood to hook up the wires and pipes again.
The Port of Portland is touting how locally made its new product is, from Oregon and Washington lumber to local steel. The roof will be held up by elegant steel Y-columns fabricated by Thompson Metal Fab Inc across the river in Vancouver. They are made from rolled steel from Evraz on North Rivergate Road.
ZGF's vision is of a space that feels unobstructed yet is compartmentalized by the undulating roof into different zones. The experience will offer travelers comfortable, cocooning chairs, with light filtered through wooden slats and picturesque views of the mountains and the planes taking off and landing. Although the terminal will be remodeled too, the roof, not the carpet, is the defining new element that will give the airport a new form and atmosphere.
Editor's note: A previous version of this story misidentified the general contractor for the project.
PDX Next is the entire $2 billion airport expansion project, consisting of five different projects.
The Terminal Core Project (internally known as TCORE) or the main terminal project includes the roof and all the work in the main terminal to expand the heart of the building 150-feet to the west. The roof is estimated to cost $100 million.
PDX Next Terminal Roof Fabrication Yard is just off Marine Drive. The new roof is a Hoffman Skanska joint venture. The project will be complete in 2025, though portions of the main terminal likely will open in 2024.
There are 200 craft workers on the side-by-side roof sites, and another 400 working at the airport on other projects.
Learn more at www.pdxnext.com.
Reporter, The Business Tribune
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