A Pennsylvania Railroad Keystone Station sign for AO interlocking tower on the PRR Main Line between Altoona and Pittsburgh PA, east of Conemaugh, PA. NOTE: this object is a scenery (building) item. It can be used by placing it next to a building. Based on PRR Drawing Number 78160-A, dated 1926. Developed using Blender 2.79 and TANE SP4 (Build 105766).