A new Sea-Tac Airport facility hopes to alleviate some of the airport’s growing pains by giving passengers a new place to gather—and board their planes without waiting for a gate to open up.

As Seattle goes through rapid growth, the impact on air travel and traffic has been immense. Sea-Tac Airport, according to the Port of Seattle, has had the fastest-growing number of passengers out of every major airport in the country for five years now, with passenger traffic increasing 43 percent from 33.2 million to 46.9 million between 2012 and 2017.

But as the passenger traffic has grown, the airport—for the most part—has not, although construction of a new international terminal is underway. During the busiest, says the Port, there’s not a single gate in the airport that’s not in use, holding flights waiting for a gate and using 100,000 gallons of fuel a month just from idling alone from May through June of this year.

The new, two-story annex to Concourse D, designed by architecture firm HOK, adds six gates and 32,400 square feet for “hardstand operations”—where rather than directly boarding or deboarding to and from the concourse, passengers are shuttled to and from a plane stopped away from the terminal building. The Port says this will accommodate the influx of passengers.

To access the facility, passengers will cross a bridge from the existing Concourse D. Like Sea-Tac’s other concourses, the area has concessions, charging stations, and restrooms.

The new facility opens to passengers later this fall. Another major expansion, an international terminal that will more than double travel capacity, is set to open toward the end of 2019.