Sometimes it feels like the new 7000 series railcar doors take forever to open. That might not be your imagination: it's probably happening due to a change in the newer railcars’ software.
Metro train doors can operate in one of two modes: automatic and manual. Automatic door operations mean that when the train pulls into a station and berths on the platform, the doors open by themselves once the train is stopped. Manual door operations mean the train operator has to push a button to get them to open.
Four different times in 2008, train doors opened when they shouldn't have (technically speaking, interference from the power system caused the high-frequency track circuits, which tell the doors when to open, to mis-trigger). Since then, train doors have been operated manually.
In addition to the two door modes, all trains have detection systems to make sure that the entire train is on the platform first before the doors are allowed to open. But for most Metro cars, this system is only enforced when the trains are operating in the computer-assisted Automatic Train Operation mode, which hasn't been used very often since 2009.
And that’s where the 7000 series cars differ from the “legacy” fleet. Whether 7000s are running in manual or automatic modes, they detect whether all cars are on the platform before the allow their doors open.
Only the Automatic Train Control system on the train's lead car is active, as it controls how the train moves and operates. The last car on 7000 trains operates in “Trailing” mode and performs a check to make sure that it’s on the platform before allowing the doors to open. The middle cars operate in “Passive” mode and don’t do anything.
The platforming detection in the 7000s requires the train operator to push a button before opening the doors to trigger the system to actually check where the train is, since they're operating in manual mode. When the operator doesn’t do this first, the train’s console will beep so they’re reminded, and it won’t let the doors open. The operator then needs to acknowledge an additional prompt making sure they really want to open the doors.
If you’re sitting up near the operator’s cab, you can hear the beeping when they forget this last step (not to be confused with the overspeed alarm, telling the operator to slow down over a section of track).
So if you’re waiting to get off of a 7000 series train and it seems like the doors are taking longer than the typical five-ish seconds to open...it could be that someone didn't push a button quickly enough.