The front one is a Rewanui Brake van which operated a brakes on to a centre rail "Fell" system. These vans were used on the Rewanui & Roa inclines in the South Island and a similar vans on the Rimitika incline in the North Island.
The rear van is modelled on a van of 1890's vintage.
The photo was taken of one of the large viaducts on Karls american railway.
