Metro will shut down six rail stations in Northern Virginia during the entirety of summer 2019 to rebuild platforms, the transit agency announced Monday.

The following stations will close between Memorial Day and Labor Day 2019: Braddock Road, King Street, Eisenhower Avenue, Huntington, Van Dorn Street and Franconia-Springfield.

Rebuilding platforms is "heavy construction activity that requires that tracks be taken out of service to allow for demolishing existing structures, access to the construction area, and concrete pouring," the transit agency said in a release.

At the Braddock Road station, as well as the Rhode Island Avenue station on the Red Line, riders have to step up or down at least 8 inches between the trains and the platforms, News4's Adam Tuss reported earlier this year. One rider said she tripped and was badly bruised. Others have said the gaps pose a safety hazard.

Metro has previously rebuilt platforms at 10 of the system's outdoor stations while keeping the stations open, but that process resulted in years of single-tracking, the agency said.

The system's outdoor platforms have structural deficiencies due to decades of exposure to the elements, Metro said.

The Braddock Road station platforms are crumbling and cracking, which has created an uneven surface and requires passengers to step up or down between the train and the platform, Tuss reported.

Via Metro - Pics from Reagan National station, King Street and Addison Road last Spring #wmata @nbcwashington pic.twitter.com/pZDPIm5ekF — Adam Tuss (@AdamTuss) May 7, 2018

The new $300 million to $400 million project will reconstruct outdoor platforms at 20 stations.

Under the first phase, Metro plans to demolish and rebuild the platforms at Braddock Road, King Street and Eisenhower Avenue, which will lead to a shutdown of rail service south of Reagan National Airport. Blue and Yellow line service will operate normally between the airport and Largo Town Center on the Blue Line and Fort Totten/Mount Vernon Square on the Yellow Line, Metro said.

Metro said it will work with local jurisdictions and other transit agencies to come up with traffic mitigation plans and travel alternatives.

Future Rebuilding Phases Set for Fall 2019-2021

Metro plans to rebuild the platforms at four more Northern Virginia stations between September 2019 and May 2020, but those station's locations and configurations will allow for construction to happen while the stations remain open, the transit agency said.

Those stations are Van Dorn Street, Franconia-Springfield, Huntington and Reagan National Airport.

During that phase, rail service is expected to run normally, with the exception of the Blue Line in September 2019, Metro said.

In 2020 and 2021, Metro plans to rebuild the platforms at the 13 remaining outdoor stations: West Hyattsville, College Park, Greenbelt, Rhode Island Avenue, Vienna, Dunn Loring, West Falls Church, East Falls Church, Cheverly, Landover, New Carrollton, Addison Road and Arlington Cemetery.

Stay with NBCWashington.com and NBC4 for more.