The cart blows past it at speed and portals a platform-sized neighbourhood boss away, leaving only a wet spot on the tiles.
Carl's abandoned Interdiction Rapid-Response Railway Repair Cart was left switched on and facing stop 24, and the monsters ignored it — helped by the fact that not many creatures are coming from that direction any more. His immediate worry on the run to the trainyard is the station itself, where his party was jumped by Krakaren babies the last time they passed.
Sure enough, a single enormous Krakaren Juvenile Cloneling stands on the platform as they blast by: a massive octopus thing with swirling tentacles, a neighbourhood boss at least as big as the one they fought on the second floor, half-slopped onto the track with its tentacles hanging casually over the platform edge. The portal takes the whole thing away and leaves a wet spot on the tiles as the cart zooms on toward the trainyard.
A tiled platform with a wet smear where a boss used to be sprawled across the rails.
The last obstacle between the party and the trainyard, cleared without slowing down.