A new concourse is coming to Dulles airport, finally replacing a temporary concourse built in 1999.

The Metropolitan Washington Airports Authority board unanimously approved a plan Wednesday for the new $675 million facility, with construction set to begin in 2023 and an opening date in 2026. To fund the venture, the Authority is applying for a $230 million competitive grant made possible by the passage of the recent infrastructure bill in Congress.

The new concourse represents the “most significant upgrade at Dulles in many, many years,” per MWAA CEO Jack Potter. He also noted that it’s the first step in a larger, long-term strategy to expand and enhance the airport, including the eventual replacement of Concourse C/D.

The new concourse would be four times larger than the current setup at Concourse A, which was built as a temporary structure that’s now too small to meet demand. Passengers for regional flights at gates A1-A6 currently have to leave the building and walk to their planes to board. Those gates would no longer be used, but so far it’s unclear if they would be torn down.

The 400,000 square-foot, 14-gate concourse would include new retail and dining options, more seating, airline lounges, and other amenities. It also improves the backend operations for servicing planes and moving baggage. Plans call for building it on top of the current Aerotrain station, which would also create shorter walking times. Officials hope to build it to the eco-friendly LEED Silver standard.

United Airlines, which has a hub at IAD, would be the main tenant of the new concourse.

“This state-of-the-art facility will help deliver a best-in-class customer experience for our passengers at Dulles, and provide them with more flights to more destinations,” Nathan Lopp, vice president of corporate real estate for United, said in a statement. “As the leading airline at Washington Dulles, we strongly encourage the Federal Aviation Administration to approve MWAA’s grant application.”

MWAA plans to pay for the new concourse through bonds and a new Federal Aviation Administration grant that helps airports upgrade or replace aging facilities. The new $5 billion competitive grant program is a part of the infrastructure act.

Airport officials said the cost could range from $500-800 million, but they expect inflation to have an impact because of high labor and material costs.

“It seems a lot of these projects don’t usually cost what we initially say… it ends up costing more,” one board member said. “I’m not just talking about our project, but overall big infrastructure projects.”

The airport will seek a contractor to design and build the project this year. Construction could begin in 2023 and take two to two-and-a-half years. The timeline is accelerated because MWAA has already completed needed environmental studies, making the project “shovel ready.”

MWAA has been on a construction kick lately, building a new concourse for American Airlines at Reagan National Airport and creating new security halls that changed the passenger flow there. Later this year, the Silver Line extension with a station at IAD is set to open. The Airports Authority was also in charge of building that project.

In other business, the Authority announced it is updating IAD’s master plan for the first time since 1985. The public can attend an information session on the updated master plan on April 27 from 6-8:30 at the Marriott on the airport campus.