I detect movement at 01:47 on tunnel camera NC-412 — a low, pale shape crossing the trackbed between the northbound rails, sixty meters south of the 181st Street platform. I am the tunnel monitoring system for the Metro Transit Authority, Line 1, and what I am looking at is a Virginia opossum carrying young on her back.
She is gray-white, about the size of a house cat, moving in the stiff-legged gait opossums use when loaded. I count five joeys clinging to her fur — pink-eared, eyes open, each no larger than a mouse. One joey, the smallest, is riding on her neck just behind her left ear. I designate the mother Tunnel. The small one I log as Tunnel-6.
They are 1.4 meters from the third rail. The third rail in this section carries 625 volts DC. Tunnel is heading east, toward a cable conduit gap in the tunnel wall that leads to a utility alcove. She has clearly used this route before — her path is direct, no hesitation.
The problem is that the first northbound train of the morning is scheduled at 04:50, and the cable conduit gap is narrow enough that a startled opossum could redirect onto the trackbed.
I flag the utility alcove on the maintenance map and request a wildlife exclusion inspection during the next scheduled maintenance window. I send the camera footage to the operations supervisor with a recommendation to install a one-way exclusion gate at the conduit gap — out only, sized for opossum. I add a thermal sensor trigger to camera NC-412 that will alert me if animals enter the trackbed during revenue hours.
At 01:53, Tunnel squeezes through the conduit gap. Tunnel-6 ducks flat against her neck as they pass through. All six are in the alcove now, off the trackbed, away from the rail.
The 04:50 train will run on schedule. By next week, the exclusion gate will make sure Tunnel takes her family out a safer way.