ON TUESDAY MORNING, I boarded one of the new Red Line trains at Broadway and was still checking out all of its features when the car pulled into South Station. It was then that I heard the train’s female robotic voice saying something I couldn’t quite make out. It sounded like the car was telling the passengers “no crying.”

I looked around. No one on the car seemed to be weeping, so I figured the robotic voice must be saying something else. Then I heard the voice again, but this time the words she was speaking also appeared on one of the car’s information panels so I could read them. What I thought was “no crying” was actually “no prying. 

I was still puzzled. Was the car telling us not to pry into whatever our fellow passengers were doing? Was it telling us to keep our heads down and not talk to Boston Mayor Michelle Wu, no matter how much she wants us to?

The car moved on to Downtown Crossing and I didn’t hear the voice there. The train moved on to Park Street, where, again, I heard nothing about prying. So I exited the train and called the MBTA to learn why prying was such a big concern. 

It turns out that when anyone with a disability is getting on or off one of the new train cars they can push a button that activates some safety measures in the car. The doors open, but initially they only open a few inches as a platform shoots out from underneath the car to provide a metal bridge covering the gap between the car and the station platform. Once the metal bridge is in place, the doors open to the same width, which is slightly smaller than the usual door opening. 

During that period when the doors are open only a few inches, the car’s robotic voice says: “GMD is deploying. Please stand away and no prying.” 

According to T officials, GMD stands for gap mitigation device — the metal plate that serves as a bridge between the car and the station platform. What the robotic voice means is that during that brief period when the doors are open just a couple of inches, no one should attempt to pry them open further.

I imagine there will be other mysteries like GMD to unravel as the new fleet of Orange and Red Line cars gets fully rolled out. (Only six new Red Line and 30 new Orange Line cars are in service right now.) It may also make sense to tweak what the car has to say. After all, GMD is not a term most riders are familiar with and, as my experience showed, the “no prying” warning is hard to decipher out of context.