(John McDonnell — The Washington Post)

This weekend, Metro is closing several stations and part of the busy Red Line that runs through the core of downtown.

Starting at 10 p.m. on Friday night through midnight Sunday, Farragut North, Metro Center, Gallery Place, Judiciary Square and Union Station will be closed. Riders can use free shuttle buses provided by Metro to get around those stations.

The Blue and Orange lines will be accessible from Metro Center and the Yellow and Green lines from Gallery Place.

The work is part of Metro’s $5 billion rebuilding plan to fix the ailing 37-year-old rail system.

For the last two years, the transit agency has been aggressively working on weekends, when it has more time to get critical equipment on the tracks and fewer riders on the system. Officials said because they have to move equipment and materials onto the tracks, there often isn’t enough time in the off-hours when the system is closed to do the work.

This weekend’s closing of the Red Line likely will affect more than a quarter of weekend riders, based on an analysis of detailed ridership from Metro statistics.

The closure comes as Metro has seen its ridership drop roughly 20 percent this week as the federal government shut down, leaving some of trains and stations nearly empty in the morning and evening rush hours. As a result, the transit agency is running only six-car trains instead of longer, eight-car trains that can fit more people.

Metro’s rail ridership dropped by 9 million trips to 209 million for fiscal 2013, compared with the previous year. Revenue is $20.3 million less than expected.