Crews in Alexandria are doing a series of balloon tests to help city officials decide the location for the new Metro station at Potomac Yard.
The balloon will take pictures and videos of each of the station's three proposed sites, and city officials said Monday that the tests "will assist in providing a future understanding of the visual impacts" that the station would have on each possible location.
The balloons will be visible above George Washington Parkway for around an hour each day, but officials ask residents to not stop on the parkway to watch the testing.
The new station, which is slated for construction along the existing Blue and Yellow Lines between the Ronald Reagan Washington National Airport and Braddock Road stations, is estimated to cost as much as $538 million to complete.
Officials don't expect to decide on the station's location for at least another year, when they expect all testing on the three sites to conclude.
The series of balloon tests will run through Dec. 7.