This is the "Hard Top Open Air Car!"
The Open Air Passenger Car is of Heavyweight design. It has three axles (six wheels) on each truck instead of the two axles per truck used for the enclosed passenger cars. To give the car a smooth ride when it was in passenger service, the floor is several inches of poured concrete. This coach, built in 1914 as a passenger coach, and later was modified as a Maintenance of Way work car that served on the Union Pacific. The car was converted to its fully open configuration when it entered excursion train service.
The seating is bench style. The large openings provide spectacular views along the route, and are the prefered seating for photographers.