This car rests at Brocken end-of-track. It is obviously a water car, but a standard gauge car, riding on a so-called narrow gauge rollbockwagen. I suspect it is for fighting fires or used to damp down the right-of-way during fire season. There's a pipe with what appears to be a hose connection beside the bottom of the ladder. Also, another connection at the centerline of the tank between the underframe and the tank.