Some of Metro's most problematic railcars would be replaced under a new proposal.

Metro staff plan to replace the 4000 series railcars with its swanky new 7000 series in a proposal due to go before its board of directors on Thursday.

The 21-year-old 4000 series breaks down nearly twice as often as other railcars, causing headaches for commuters and Metro mechanics alike. Metro has 100 of the cars in its fleet of 1,104.

But it will be years before the cars can be replaced, The Washington Post first reported.

Metro is already planning to replace its 1000 series railcars, which collapse into themselves during collisions and have been singled out by safety experts as particularly dangerous. It also will start to replace its 2000, 3000 and 5000 series railcars under the proposal due to the board this week.