This car, WP 11012, from the WP series 11001-11040 was built in 1927 by Western Wheeled Scraper Co. for Six Companies, Inc, and used for the building of Hoover Dam. WP bought their 40 cars from Six Companies after the dam was completed. Cars of this type were used by the WP to haul rock and ballast in Maintenance-of-Way service. Originally painted black with large white Western Pacific on the sides they ended up being painted yellow.
They were used by the WP right up to the Union Pacific takeover. They were changed very little during service, and 11012 is a good representative of this class of car.