Planning By the 1980s, three rapidly growing areas in California –
Silicon Valley, the
Tri-Valley, and the
San Joaquin Valley – were poorly connected by public transit, as
Interstate 580 and
Interstate 680 became more congested. Commuting from the San Joaquin Valley or the Tri-Valley to Silicon Valley required using a car or limited bus service. In 1989, the San Joaquin Council of Governments, Stockton Chamber of Commerce, and the Building Industry Association of the Delta started work on a 20-year transportation plan for the northern section of the San Joaquin Valley. In November 1990,
San Joaquin County voters passed Measure K, a half-cent sales tax to fund a variety of transportation improvements. The highest-priority project was the establishment of passenger rail service to San Jose. In 1995, San Joaquin County and seven cities along the route formed the San Joaquin Regional Rail Commission (SJRRC) to oversee the creation of the service. Cost sharing for capital projects, excluding stations, during the initial 36 months of service was determined by the JPA on a case-by-case basis and approved by each of the member agencies. The initial purchase of rolling stock, construction of stations, and other start-up costs, amounting to some $48 million, were covered primarily by Measure K funds. Station improvements are the responsibility of the county in which the station is located. ACE pays the Union Pacific Railroad about $1.5 million per year to use their tracks. ACE trains also use about of Caltrain track in San Jose.
Service expansion The original service used two trainsets, each with four bilevel coach cars, for a total seated capacity of 1,120 passengers in each direction daily. In September 1999, less than a year after opening, the service reached 1,000 daily riders per direction, near full capacity. To enable more trains on the line, ACE funded $3 million in track improvements, but the limited amount of equipment allowed ACE to add only a morning "
short turn" run between San Jose and Pleasanton. This "turn-back train" started service on February 21, 2000, and gave Pleasanton and Fremont a third inbound train to alleviate the crowding on the two earlier trains. Even with the added capacity, by early 2001 ACE was regularly carrying more than 700 daily standees. ACE purchased additional equipment, allowing the "turn-back train" to operate to Lathrop/Manteca station – nearly the full length of the route – beginning on March 5, 2001. Trains also began stopping at
Santa Clara station. Although the third train added 560 seats in each direction, it brought an immediate increase of 380 daily riders. ACE then planned to add a fourth round trip later in the year, with fifth and sixth round trips by 2006. On August 28, 2006, ACE added a fourth round trip, which operated midday using one of the existing trainsets. On May 14, 2012, ACE restored service to Santa Clara station. On October 1, 2012, a fourth rush-hour round trip was added, running approximately one hour after existing trips.
Altamont Corridor Express In December 2012, the service was rebranded from Altamont Commuter Express to Altamont Corridor Express to reflect plans for a broader scope of service. In March 2014, ACE opened a $65 million, maintenance facility in Stockton. On July 1, 2015, management and governance of the
San Joaquin passed from Caltrans to the new San Joaquin Joint Powers Authority. The SJRRC continued to handle normal operation and administration. On March 7, 2016, an ACE train was derailed by a mudslide in
Niles Canyon near
Sunol. The front car plunged into the rain-swollen
Alameda Creek. Fourteen passengers were injured, but there were no fatalities. ACE received
Road Repair and Accountability Act funds in January 2018 to begin Saturday service. Two Saturday round trips were added on September 7, 2019. Saturday service was suspended effective March 21, 2020, due to the COVID-19 pandemic. One weekday round trip was suspended on March 23 and another on April 6. One of the suspended weekday round trips returned on May 3, 2021, followed by the fourth round trip on September 7, 2021. On November 18, 2024, the latest evening eastbound train was replaced with a mid-afternoon train.
Future plans ACEforward In association with the
California High-Speed Rail project, ACE developed plans to upgrade and expand service. Beginning around 2008, initial plans called for the Altamont Corridor Rail Project to produce a
high speed rail, branded "Super ACE", capable of halving the travel time between San Jose and Stockton. As the high-speed rail project was scaled back and rerouted to
Pacheco Pass several years later, these plans were replaced with the more modest '
ACEforward''''' program. The San Joaquin Regional Rail Commission issued a notice of intent to proceed with an
Environmental Impact Statement in June 2013; this was released in 2017 and prioritized goals as either long term or short term. Also studied were possible connections with
BART at
Union City or the
Tri-Valley via traditional ACE rail,
diesel multiple units, or bus bridges. This connection is planned to be facilitated by the Tri-Valley–San Joaquin Valley Regional Rail Authority. The California state senate allocated $400 million in revenue from a
gas tax increase to ACE
forward expansion.
Valley Rail However, during the development of ACE
forward, significant financial and logistical challenges to expanding service on the existing route between Stockton and San Jose were identified, and further work on the project was halted in favor of a new
Valley Rail project, focusing initially on the eastern expansion to serve commuters living in the
Central Valley. ACE was awarded $500.5 million in April 2018 for expanded service to Ceres and Sacramento to provide more rail service and connections within the
Central Valley. Service is expected to begin from Ceres by 2023 The Union Pacific right of way between Ceres and Lathrop will be
double tracked to facilitate passenger service. platforms are being extended to accommodate longer trains. Valley Rail also includes a project segment to route ACE and Amtrak
Gold Runner along the little-used
Sacramento Subdivision between Stockton and Sacramento. Six new stations would be constructed along the line with a layover facility at Natomas. Trains would run the length of the line from Natomas to San Jose or Ceres with a midday
short turn to Stockton. A Draft Environmental Impact Statement was released in 2020, with services expected to begin no later than 2023. The North Elk Grove station was eliminated from planning in September 2020. The project received funding via California's Transit and Intercity Rail Capital Program in 2023, by which time the project was expected to open in phases beginning in 2025. Later that year, the estimated commencement of service to Ceres and Natomas were again pushed back to 2026, with service to Merced and infill stations opening by 2030. == Service ==