Metro announced Monday that reduced rail service levels will continue through the end of the year as the agency works to return its 7000-series rail cars to service.

       The trains, the newest in Metro’s inventory, make up 60 percent of the transit agency’s fleet but have been sidelined since the October derailment of a Blue Line train near the Arlington Cemetery station.

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       Trains on the Red Line will continue to run every 12 minutes, while operating every 20 minutes on the Green and Yellow lines. Officials said Monday that trains on the Orange, Blue and Silver lines will run every 24 minutes. Trains at some stations will arrive more frequently where rail lines overlap.

       Metro takes more than half its rail cars out of service after investigation uncovers safety issues

       Metro said January service levels will depend on the successful completion of tests and restoration plans for its 7000-series rail cars.

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       No one was injured in the Oct. 12 incident, but an initial investigation by the National Transportation Safety Board found defects in the trains’ wheelsets that could make them more prone to derailment. Similar defects in that series of trains had been identified as early as 2017, but Metro considered those to be rare and isolated warranty issues.

       Those findings prompted the Washington Metrorail Safety Commission to order the transit agency to pull all 7000-series trains from service until the trains could be inspected and Metro could develop a plan for their safe return. The commission is an independent agency responsible for safety oversight of the transit agency.

       Metro has proposed more frequent inspections of the trains — every eight days rather than the previous 90 days — in hopes that it would be able to spot early indications of any possible defect before it poses a danger. Earlier this month, it began testing two 7000-series trains as part of that effort. However, because defects can be progressive and appear after an unknown number of miles, they can be difficult to pinpoint, investigators said.