The July and August numbers represent a significant slowdown in the pace of the errors, which occurred as frequently as four times a week in the first month after Metro disabled its automatic doors system in April, forcing operators to open doors manually by pushing a button.
The most recent incidents occurred at the Dupont Circle station the morning of July 22, at West Falls Church the afternoon of July 25, and at Judiciary Square mid-day Aug. 3.
Almost all of the incidents this year have been the result of operators forgetting they were driving eight-car trains instead of six-car trains and not properly stopping the train at the end of the station, leaving the back car hanging in the tunnel.
Metro General Manager John Catoe said in June he was considering ordering operators to stop all cars at the eight-car mark at the far end of the platform to help reduce the errors, but was reluctant to make the change because riders would have to adjust to new boarding spots for six-car trains.
"That means we're telling our customers they have to change because we can't get it right," he said. "That's a pretty powerful message."
Metro did not change its boarding setup but did take other preventive measures, such as installing eight-car markers on some station platforms that indicate where the trains should stop, handing operators placards that say "8" to place on their train consoles, and having supervisors remind operators during their shift that they have eight-car trains.
"Based on our records, we do think there's been some considerable improvement," said Dan Epps, Metro's managing director of rail transportation. "We're continuing to reinforce what we've put out there in an effort to try to eliminate this altogether."
While no riders have been injured because of the errors, they comprise some of Metro's most serious safety violations, because passengers who exit the back railcar could fall onto the tracks.
Operators were fired in two of the incidents, transferred to non-operator positions in three of the cases and suspended in the remaining 18 incidents this year.
Metro officials disabled the system's automatic door feature in April because it was malfunctioning and had opened the doors on the wrong side of the train four times in 100 days, they said.
Metro engineers are scheduled to finish installing and testing new electrical equipment in all of the railcars by January, which will enable officials to resume the use of the automatic system, Epps said.