Portal-equipped maintenance cart hauled onto the employee track to open the train's route to the abyss.
Carl and Katia Grim carried the Interdiction Rapid-Response Railway Repair Cart by hand, turned it and positioned it on the employee track, its wheels fitting just inside the wider rails. Its portal was the door through which The Nightmare Express was sent across the floor into The Abyss.
Once the train had passed through, Zhang climbed back in and switched the portal off. Afterward Carl scolded Princess Donut for having risked both herself and the cart to come after him; she was unrepentant. The party then rode or walked the employee line back up to Station 36.
A small rail maintenance cart sized for the wider employee track, fitted with a portal generator and controls.
The crew's mobile portal platform and the delivery mechanism for the train bomb.