The Altamont Corridor Express (also known as ACE, formerly Altamont Commuter Express) is a commuter rail service in California, connecting Stockton and San Jose during peak hours only. ACE is named for the Altamont Pass, through which it runs.[4] Service is managed by the San Joaquin Regional Rail Commission, and operations are contracted to Herzog Transit Services, using AAR assigned reporting mark ACEX.[4][5] The 86-mile (138 km) route includes ten stops, with travel time about 2 hours and 12 minutes end-to-end. The tracks are owned by Union Pacific Railroad, previously built along the Western Pacific Railroad main line. ACE uses Bombardier BiLevel Coaches, MPI F40PH-3C locomotives, and Siemens Charger locomotives. MPI F40PH-3C Bombardier BiLevel VI Cab Car Bombardier BiLevel VI Coach
