Secondary retention device for bi-parting doors

A bi-parting door assembly for a transit vehicle having a door opening formed in a wall of the transit vehicle, the door assembly comprising:

• a first door and a second door disposed adjacent to the wall;
• a door operator system configured to move the first door and the second door in opposing directions along the door opening between respective open and closed positions, the door operator system comprising a door operator frame configured to be mounted on the transit vehicle above the door opening;
• and
• a retention mechanism for the first door and the second door, the retention mechanism comprising:
• a first track connected to the first door, the first track having a first end and a second end, wherein the first track is movable with the first door between the open position and the closed position;
• a second track connected to the second door, the second track having a first end and a second end, wherein the second track is movable with the second door between the open position and the closed position;
• a first retention assembly connected to the door operator frame, the first retention assembly being configured to retain the first track in the closed position;
• a second retention assembly connected to the door operator frame, the second retention assembly being configured to retain the second track in the closed position;
• a first engagement member connected to the second end of the second track, the first engagement member being configured to engage the first retention assembly to cause the first retention assembly to move to retain the first track in the closed position when the second track is in the closed position;
• and
• a second engagement member connected to the second end of the first track, the second engagement member being configured to engage the second retention assembly to cause the second retention assembly to move to retain the second track in the closed position when the first track is in the closed position.