Union Pacific’s West Local switches Rocky Spur on July 8, 2012. Three clean Union Pacific GP40-2s (two rebuilt from Southern Pacific GP40s, while one is a former Cotton Belt locomotive) switches Western Aggregates at the end of the line. Rocky Spur, now labeled the Rocky Flats Industrial Lead, is a 3.9-mile line runs north out of Rocky, Colorado, on the Moffat Tunnel Subdivision.