Riders get on a Metro train.

Q. Red Line rider Ben Proshek asked us what’s behind the annoying five- or six-second wait for the doors to open after trains stop at a platform.

This question comes up often.

The Post’s Dr. Gridlock gave part of the answer in a column four years ago: The driver’s seat is on the right, so if the platform is on the left, the driver has to get up to look out the left side window and then hit a button on a panel that’s also on the left.

But one Metro driver who didn’t want to be named because they’re not authorized to speak publicly said there’s more to it than that.

The delay is “a safety precaution Metro instituted when there was a wave of operators opening the door off the platform or on the wrong side,” the driver said.

So now operators have to look out the window for three to five seconds upon stopping to make sure all of the train is fully on the platform and to make sure they know which side the doors should open.

On all trains, they have to hit a button to open the doors. But on the new 7000-series trains, they also have to verify that’s what they want to do by hitting another button.

A January 2017 post explaining the delays by Greater Greater Washington noted trains can be set to open the doors automatically, but operators have had to do it manually after four incidents in which the doors automatically opened when they shouldn’t have.

Let us know what frustrates or confounds you about Metro. Reach us at kery.murakami@washpost.com or @theDCrider.

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