For anyone who has suffered long, anxious waits in a security line at Seattle-Tacoma International Airport lately, June could be something of a test run for efforts to speed things up.
The airport, which expects pre-pandemic levels of travelers during the June-August summer season, is in the midst of a $5 billion multi-year series of upgrades aimed at smoothing passenger flows and shrinking security lines that have stretched into the parking garage and made national news.
Across the airport, crews and equipment are busy on projects ranging from wider access roads and reengineered checkpoints to modernized baggage handling, new restrooms and four new floors on C concourse.
Work on two checkpoints is expected to finish in early June, while much of the rest of the renovations, collectively dubbed Upgrade SEA, will wrap up by July 2026, when Seattle hosts six matches in the World Cup soccer playoffs at Lumen Field, expected to draw hundreds of thousands of fans.
But getting there will be immensely complicated. Sea-Tac is one of the busier airports in the country – it ranked 11th in 2022, according to federal data – thanks in part to a strong economy and a huge tourism industry, said Lance Lyttle, managing director of the aviation division at the Port of Seattle, which operates Sea-Tac.
Yet it’s also one of the smallest major U.S. airports, with just 89 gates on a footprint of around 2,500-acres. By comparison, Hartsfield-Jackson Atlanta International Airport, the nation’s busiest, has 195 gates on 4,700 acres. Denver International has 146 gates on a whopping 33,000 acres.
Sea-Tac’s smaller footprint magnifies its congestion problems.
For example, although Sea-Tac’s security lines aren’t any longer than at Denver or Atlanta, Lyttle said, because “we don’t have space to queue people, the line ends up going onto the parking garage.”
As important, Sea-Tac’s diminutive footprint makes it harder to fix the congestion.
Where larger airports can temporarily close off a concourse while construction work is underway, space is such a premium at Sea-Tac that airport renovations and passenger vacations are essentially going to happen simultaneously.
“We can’t close anything,” said Greg Carey, assistant director of the airport’s aviation project management group. “So we’re constantly building around the passengers.”
Or as Lyttle puts it, “it’s like doing surgery on the marathon runner while she’s still running the marathon.”
To make that operation successful, upgrades are being rolled out according to a carefully orchestrated timeline that, in theory, lets security, baggage operations and other passenger-facing functions be shifted smoothly as each area is completed.
Work on checkpoints 2 and 3, for example, was timed for the window between spring break and the start of the summer traveling season, with checkpoint 3 closing only after 2 was completed.
Those renovations will add four more security lanes, or enough to boost the number of passengers passing security by 600 per hour, to 5,100, said airport spokesperson Perry Cooper. With peak volumes already hitting 5,000 an hour, those four lanes will significantly cut wait times.
One caveat: Because checkpoint 3 won’t reopen until early June, after the busy Memorial Day weekend, travelers are advised to allow extra time for parking and security.
To minimize disruptions to the World Cup, a major part of the upgrade — a $1 billion-plus build out of S Concourse — won’t start until after games conclude.
Together with recent improvements, such as reserved terminal parking and SEA Spot Saver, which lets passengers make reservations for security screening, Upgrade SEA will allow Sea-Tac to get more performance out of an existing footprint that is both small and relatively old: concourses A, B and C all opened before 1967, while the South and North satellites opened in 1973.
But to handle expected increases in regional travel demand, Port of Seattle officials say they’ll eventually need a larger footprint and, ultimately, a second regional airport.
The Port has proposed an expansion on the north side of Sea-Tac with 19 additional gates, known as the Sustainable Airport Master Plan. That plan, currently under review, would boost Sea-Tac’s capacity to around 56 million passengers a year, or around 5 million more than it saw in 2023, Lyttle said.
A second phase, still on the drawing board, would raise capacity to 66 million.
“After that, that’s it,” Lyttle said. “Another airport is needed.”
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