The prototype bridge for this kit is a Southern Pacific bridge in Piru, CA. It is a very common design that has been used throughout North America, and even other parts of the world. The model, as built from the plans, spans 21 inches. It is approximately 4-3/8 inches high and 2-7/8 inches wide. From railhead to bottom of shoe is approximately 15/16 inch. The parts are made from injection molded, impact grade styrene plastic. Central Valley Model Works no. 1902.