Altamont Commuter Express trains operate on an 82-mile route between Stockton and San Jose, Calif., through the San Joaquin, Central, and Silicon Valleys. ACE trains use a combination of Caltrain and Union Pacific tracks (including the former Western Pacific line over Altamont Pass), serving ten stations.
ACE commuter service is governed by the Altamont Commuter Express Joint Powers Authority (JPA), formed in 1997 by Alameda, San Joaquin, and Santa Clara counties to coordinate management and funding. The start-up of service was financed primarily by Measure K, a half-cent sales tax earmarked for transportation, approved by San Joaquin County voters in 1990, with federal money providing the balance. The service is managed by JPA member agency San Joaquin Regional Rail Commission, and trains are operated under contract by Herzog Transit Services. Union Pacific owns the tracks.
Service began on October 19, 1998. Trains operate in push-pull fashion with F40PH-3Cs built by Morrison-Knudsen and successor MotivePower, Inc., and bilevel coaches from Bombardier. Initial operations consisted of two round trips, with a a morning turn-back between San Jose and Fremont added in February 2000. On March 5, 2001, the turn-back train was dropped and a third round trip was added departing Lathrop-Manteca later in the morning and returning in the evening. Concurrent with the March schedule change, ACE trains added a stop at Caltrain's station in downtown Santa Clara.
A fourth round trip was added in August 2006.
In midday and late evening, passengers can also board an ACE bus from San Jose to Stockton. ACE worked out a temporary trackage rights agreement with Union Pacific that expires December 31, 2003. The success of the service, which carries about 2,200 passengers each way, has prompted the Authority to seek permanent trackage rights.
At the San Jose Diridon station, passengers can connect to Amtrak and Caltrain commuter trains. Local bus operators provided free connections between ACE rail stations and employment sites.
There is no service on weekends or holidays.