Altamont Corridor Express

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Altamont Corridor Express
Altamont Corridor Express logo.svg
Altamont Corridor Express train climbing its namesake Altamont Pass
Altamont Corridor Express train climbing its namesake Altamont Pass
OwnerSan Joaquin Regional Rail Commission
Area served San Joaquin Valley, Tri-Valley and Silicon Valley
Transit type Commuter rail
Number of stations10
Daily ridership6,200 (weekdays, Q4 2021) [1]
Annual ridership227,900 (2021) [1]
Headquarters Robert J. Cabral Station
Stockton, California
Began operationOctober 19, 1998; 23 years ago (1998-10-19) [2]
Operator(s)Herzog Transit Services
Reporting marksACEX [3]
Infrastructure manager(s) Union Pacific (Stockton–Santa Clara)
Caltrain (Santa Clara–San Jose)
Number of vehicles10 locomotives, 30 passenger cars
Train length1-2 locomotives, 4-8 passenger cars
System length85 mi (137 km)
Track gauge4 ft 8+12 in (1,435 mm) standard gauge
Average speed39 mph (63 km/h)
Top speed79 mph (127 km/h)
System diagram

Valley Rail
Valley Rail
Natomas/Sacramento Airport
Old North Sacramento
Sacramento RT Light Rail
Midtown Sacramento
( Sacramento RT Light Rail)
City College
Sacramento RT Light Rail
ACE service facility
Altamont Corridor
Vision (2023/2027)
Altamont Corridor
North Lathrop
BSicon TIME.svg
Manteca Transit Center
layover facility
bus bridge
Phase 1 (2023)
Phase 2 (2027)
Layover and
maintenance facility
Merced CAHSR
Greenville Road
(planned Valley Link)
Vasco Road
Left arrow Amtrak to Oakland & Seattle
Left arrow BART Right arrow
Amtrak (planned)
Santa Clara–
Great America
Amtrak Santa Clara VTA
Santa Clara
Caltrain Amtrak San Jose International Airport
San Jose
Santa Clara VTA Caltrain Amtrak
Down arrow
Caltrain to Tamien
Coast Starlight to Los Angeles

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. [4] The 86-mile (138 km) route includes ten stops, with travel time about 2 hours and 12 minutes end-to-end. In 2021, the line had a ridership of 227,900, or about 6,200 per weekday as of the fourth quarter of 2021. ACE uses Bombardier BiLevel Coaches, MPI F40PH-3C locomotives, and Siemens Charger locomotives.

Service began on October 19, 1998, with two weekday round trips. A third round trip was added in May 2001, followed by a fourth round trip in October 2012. Saturday service commenced in September 2019. As of 2018, average weekday ridership is 5,900. [5]

The tracks are owned by Union Pacific Railroad, previously built along the Western Pacific Railroad main line. Under the ACEforward program, a number of improvements to the service are being considered. These include a rerouted line through Tracy, an extension to Modesto and Merced, and connections to BART at Union City and Tri-Valley.

History and funding


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. [6] [7] The highest-priority project was the establishment of passenger rail service to San Jose. [2]

Former ACE logo, used until 2013

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. [2] In May 1997, the Altamont Commuter Express Joint Powers Authority (ACE JPA) was formed by the SJRRC, Santa Clara Valley Transportation Authority (VTA), and Alameda Congestion Management Agency (ACMA). That agreement formalized financial support, administrative processes, and governance for the rail service. [2] The operation is funded by a variety of state and federal sources, largely sales tax revenue collected by the three JPA signatories, while farebox revenues account for about one-third of costs. [8]

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 4 miles (6.4 km) of Caltrain track in San Jose. [9] Service began on October 19, 1998, with two daily round trips running to San Jose in the morning and Stockton in the evening. [6]

Service expansion

ACE service to Santa Clara station began in 2001, was suspended in 2005, and returned in 2012.

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. [10]

With that success, the agency wanted to add additional runs. To enable more trains on the line, ACE funded $3 million in track improvements, [11] but the limited amount of equipment only allowed ACE to add 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. [12] Even with the added capacity, by early 2001 ACE was regularly carrying more than 700 daily standees. [13]

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. [14] 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. [13] However, by late 2001, the deepening dot-com recession was severely hurting ridership, and expansion plans were put on hold. On June 30, 2003, the ACE JPA was dissolved in favor of a Cooperative Services Agreement between the three member agencies. [2]

On January 6, 2003, ACE introduced the Stockton Solution Shuttle, allowing Stockton passengers to use the ACE trip which terminated at Lathrop/Manteca. [10] The trip was extended to Stockton on August 1, 2005. At that time, service to Santa Clara was suspended to allow for the construction of a second platform and pedestrian tunnel at the station. [15]

On August 28, 2006, ACE added a fourth round trip, which operated midday using one of the existing trainsets. [2] On November 7, 2006, San Joaquin County voters approved a 20-year extension of Measure K. [7] Suffering from reducing funding due to the Great Recession, ACE cut the lightly used midday trip on November 2, 2009. [10] On May 14, 2012, ACE restored service to Santa Clara station. [6] [16] On October 1, 2012, a fourth rush-hour round trip was added, running approximately one hour after existing trips. [10]

Altamont Corridor Express

Car in new Altamont Corridor Express livery at Fremont station in July 2018

In December 2012, the service was rebranded from Altamont Commuter Express to Altamont Corridor Express to reflect plans for a broader scope of service. [17]

In March 2014, ACE opened a $65 million, 121,000-square-foot (11,200 m2) maintenance facility in Stockton. [18] On July 1, 2015, management and governance of the San Joaquin passed from Caltrans to the new San Joaquin Joint Powers Authority. [19] The SJJPA has nominal control over the SJRRC, but delegates all responsibility over ACE to the SJRRC.

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. [20] [21]

ACE received Road Repair and Accountability Act funds in order to initiate Saturday service in January 2018, [22] with two Saturday round trips added in September 2019.

Future plans

In association with the California High-Speed Rail project, the ACE line is been planned to be dramatically upgraded and expanded. Beginning around 2008, initial plans called for the Altamont Corridor Rail Project to produce a high speed rail "Super ACE" capable of halving the travel time between the endpoints. [26]

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; [27] this was released in 2017 and prioritized goals as either long term or short term. [28] Short term goals included track improvements, a possible reroute through downtown Tracy including new stations, a West Tracy station, and a new extension to Modesto in addition to additional daily round trips. Long term goals included upgrades to the existing corridor to allow as many as 10 daily round trips, extension to Merced and electrification of the line from Stockton to San Jose. [28]

Also under studied were possible connections with BART at Union City or the Tri-Valley [29] [30] via traditional ACE rail, diesel multiple units, or bus bridges. [31] This connection is planned to be facilitated by the Tri-Valley-San Joaquin Valley Regional Rail Authority. [32]

Altamont Corridor Vision

The state senate allocated $400 million in revenue from a gas tax increase to ACEforward expansion. [28] ACE was awarded $500.5 million in April 2018 for expanded service to Ceres and Sacramento [33] to provide more rail service and connections within the Central Valley. [34] [35] Service is expected to begin from Ceres by 2023 [36] with interim bus bridge service to Merced until that segment of Union Pacific right-of-way is upgraded. Four trains will depart Ceres in the mornings, and one train may make the complete run to San Jose with others transferring passengers at North Lathrop. [37]

By 2019, the plan had come to be called the Altamont Corridor Vision, with an expected price of $9.7 billion, allowing ACE to run up to six weekday round trips in 2023 with the goal of ten weekday round trips once additional track infrastructure is completed. ACE and the Tri-Valley-San Joaquin Valley Regional Rail Authority sought funding to construct a shared tunnel under Altamont pass in order to speed service and increase reliability. [38] The Union Pacific right of way between Ceres and Lathrop will be double tracked to facilitate passenger service. [36] As of 2019 platforms are being extended to accommodate longer trains. [39]

Valley Rail

Valley Rail is the project to route ACE and Amtrak San Joaquins 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 begin no later than 2023. [40] The North Elk Grove station was eliminated from planning in September 2020. [41]


As of July 2019, ACE operates four round trips per weekday in the peak rush hour directions – westbound (to San Jose) in the morning and eastbound (to Stockton) in the evening. Trains are scheduled to make the 85-mile (137 km) one-way trip in 2 hours 12 minutes, an average speed of 39 miles per hour (63 km/h). [42]

ACE did not operate on weekends or major holidays until September 7, 2019, when two Saturday round trips were added. [43]


Altamont Corridor Express train crossing the San Francisco Bay National Wildlife Refuge between Fremont and San Jose

From San Jose to just north of Santa Clara, ACE uses the Caltrain main line (Peninsula Subdivision), shared with Caltrain and Amtrak service. From Santa Clara to Stockton – the majority of the route – ACE runs on Union Pacific Railroad freight lines. From Santa Clara to Newark, ACE uses the Coast Subdivision, then the Niles Subdivision to Niles. From Niles to Lathrop, the line uses the Oakland Subdivision. [44] [45] From Lathrop to Stockton, the line uses the Fresno Subdivision.

The route runs through Niles Canyon, parallel to the Niles Canyon Railway, Highway 84, and the Hetch Hetchy Aqueduct. The line passes through a 0.75-mile (1.21 km) long tunnel which cuts off one of the canyon's horseshoes. This tunnel was modified from its original configuration to accommodate intermodal double-stack freight trains. However, this left the track in poor condition, reducing speeds from 45 mph (72 km/h) to 25 mph (40 km/h) in the summer and as low as 10 mph (16 km/h) during the rainy season. The San Joaquin Regional Rail Commission plans to rehabilitate the tunnel. [46]

East of Pleasanton and Livermore, the line runs through the Altamont Pass on the original Feather River Route. After crossing the California Aqueduct and the Delta-Mendota Canal into the Central Valley, skirting the southern edge of Tracy. It then turns north between Lathrop and Manteca and runs to Robert J. Cabral Station in Stockton.

Tickets and fares

ACE tickets are available at select stations and on ACE's web site. Distance-based fares are available in one way, round trip, 20 trip, and monthly passes.

Rolling stock

Charger locomotive at Santa Clara in 2021

ACE operates push-pull trains with one to two diesel locomotives and four to eight bilevel coach cars. [9] Trains typically operate with the locomotive(s) leading westbound and the cab car leading eastbound.

ACE has ordered 17 additional Bombardier BiLevel cars (5 cab cars and 12 coaches). Deliveries were expected to begin sometime in 2021. The entire fleet of Bombardier bilevel coach cars and MPI F40PH-3C locomotives will be rebuilt, overhauled, and repainted to have a matching paint scheme, except for two that were retired in May 2020. They will then continue to operate along with the newer Siemens Charger SC-44 locomotives, which entered service in 2020. [47]

Model Quantity Number Notes
MPI F40PH-3C 4 3102-3105
Siemens Charger 4 3110-3113
Bombardier BiLevel VI coach 22 3201-3222
Bombardier BiLevel VI cab car 8 3301-3308
Bombardier BiLevel IX coach 12 TBD Deliveries starting late 2021
Bombardier BiLevel IX cab car 5 TBD Deliveries starting late 2021

See also


  1. ^ a b "Transit Ridership Report Fourth Quarter 2021" (PDF). American Public Transportation Association. March 10, 2022. Retrieved June 7, 2022.
  2. ^ a b c d e f "History of ACE". San Joaquin Joint Powers Authority.
  3. ^ "AAR Railroad Reporting Marks (2015)". Railserve. Retrieved June 28, 2016.
  4. ^ a b Solomon, Brian (2013). North American Railroad Family Trees : An Infographic History of the Industry's Mergers and Evolution. Minneapolis, MN: Voyageur Press. p. 127. ISBN  978-0-7603-4488-0.
  5. ^ "Transit Ridership Report: Second Quarter 2018" (PDF). American Public Transportation Association. August 24, 2018. Archived from the original (PDF) on October 4, 2018. Retrieved December 6, 2018.
  6. ^ a b c "Altamont Corridor Express (ACE)". BayRail Alliance.
  7. ^ a b "Measure K". San Joaquin Council of Governments. Archived from the original on September 2, 2016. Retrieved August 29, 2016.
  8. ^ "2014-2015 WORK PROGRAM & BUDGET" (PDF). San Joaquin Regional Rail Commission. June 6, 2014. p. 6.
  9. ^ a b Van Hattem, Matt (June 30, 2006). "Altamont Commuter Express: The commuter rail service linking San Jose and Stockton, Calif". Trains Magazine. Retrieved August 23, 2006.
  10. ^ a b c d Cox, Jeremiah (July 10, 2013). "Altamont Commuter Express on the SubwayNut". Subway Nut.
  11. ^ Cabanatuan, Michael (November 16, 1999). "ACE to Add Third Morning Train / Pleasanton-to-San Jose service will begin by Feb 15". San Francisco Chronicle. Retrieved August 29, 2016.
  12. ^ "History". San Joaquin Regional Rail Commission. Archived from the original on May 11, 2000.
  13. ^ a b White, Mike (March 12, 2001). "4th Ace train to bolster the fleet". Press Herald. Archived from the original on November 8, 2001 – via San Joaquin Regional Rail Commission.
  14. ^ Bott, Fran (March 1, 2001). "Third ACE train ready to roll". The Record. Archived from the original on November 8, 2001 – via San Joaquin Regional Rail Commission.
  15. ^ "Schedule Changes will be effective August 1, 2005" (PDF). San Joaquin Regional Rail Commission. August 1, 2005. Archived from the original (PDF) on November 26, 2005.
  16. ^ "ACE | Altamont Corridor Express". San Joaquin Regional Rail Commission. Archived from the original on May 8, 2012.
  17. ^ "SJRRC Refreshes ACE Brand with new Logo" (Press release). San Joaquin Regional Rail Commission. December 10, 2012 – via Mass Transit Magazine.
  18. ^ Rembulat, Vince (March 23, 2014). "ACE opens $65M state-of-art facility". Merced Bulletin. Archived from the original on September 16, 2016. Retrieved August 29, 2016.
  19. ^ Sheehan, Tim (June 26, 2015). "Valley agency takes control of Amtrak San Joaquin trains". Fresno Bee. Retrieved August 29, 2016.
  20. ^ "Fallen Tree Derails Train in California; At Least 9 Injured". New York Times. Retrieved March 8, 2016.
  21. ^ Tucker, Jill; Lyons, Jenna; Cabanatuan, Michael. "14 hurt as commuter train derails -- no ACE service Tuesday". SFGate. Retrieved March 8, 2016.
  22. ^ Wanek-Libman, Mischa (January 31, 2018). "California rail providers receive $52M in state funding". RT&S. Retrieved February 2, 2018.
  23. ^ "Executive Summary" (PDF). ACE Rail. ACE. Archived from the original (PDF) on May 29, 2018. Retrieved June 2, 2017.
  24. ^ "Chapter 2 2 Description of Phase I Improvements" (PDF). ACErail. ACE. Archived from the original (PDF) on April 29, 2018. Retrieved April 28, 2018.
  25. ^ "HERE COME THE TRAINS". Manteca Bulletin. April 27, 2018. Retrieved April 28, 2018.
  26. ^ Johnson, Zachary K. (November 13, 2009). "'Super ACE' rail project touted". Modesto Bee. Retrieved August 22, 2016.
  27. ^ "NOTICE OF PREPARATION OF AN ENVIRONMENTAL IMPACT REPORT". San Joaquin Regional Rail Commission. June 24, 2013. Archived from the original on May 31, 2016. Retrieved August 13, 2013.
  28. ^ a b c "ACE expansion report released". Tracy Press. May 31, 2017. Retrieved June 2, 2017.
  29. ^ "ACEforward Alternatives Analysis and Development (presentation at SJRRC Board Meeting)" (PDF). San Joaquin Regional Rail Commission. April 4, 2014.
  30. ^ "ACEforward – Improving the Altamont Corridor Express" (PDF). San Joaquin Regional Rail Commission. July 2015.
  31. ^ "Valley Link Project – APTA Economic Impact Analysis" (PDF). May 13, 2020. Retrieved July 21, 2021.
  32. ^ "Valley Link Project". Retrieved July 21, 2021.
  33. ^ Holland, John (April 27, 2018). "Expanded train service coming to Modesto, Merced; what it means for commuters". Modesto Bee. Retrieved April 28, 2018.
  34. ^ Vaughn, Danielle (February 8, 2017). "San Joaquin rail service plans expansion of Sacramento route". Lodi News-Sentinel. Retrieved February 14, 2017.
  35. ^ "NOTICE OF PREPARATION OF AN ENVIRONMENTAL IMPACT REPORT: ACE Extension Lathrop to Ceres/Merced" (PDF). San Joaquin Regional Rail Commission. January 10, 2018.
  36. ^ a b Wyatt, Dennis (October 9, 2019). "ACE on track for Manteca & Ripon stops". Manteca Bulletin. Retrieved October 14, 2019.
  37. ^ "ACE Extension Lathrop to Ceres/Merced Draft EIR Executive Summary ES.3.1.2 Operation and Maintenance" (PDF). San Joaquin Regional Rail Commission. Archived from the original (PDF) on January 15, 2019. Retrieved January 14, 2019.
  38. ^ Holland, John (September 1, 2019). "Forty trains a day through Altamont at up to 125 mph? It could happen, weary drivers". Modesto Bee. Retrieved September 18, 2019.
  39. ^ "SJRRC selects LAN for Altamont Corridor Express Platform Extension Project". Mass Transit. Lockwood, Andrews & Newnam Inc. November 27, 2019. Retrieved December 6, 2019.
  40. ^ "Valley Rail Sacramento Extension Project Draft Environmental Impact Report" (PDF). ACE. AECOM. Retrieved May 9, 2020.
  41. ^ "Valley Rail Sacramento Extension Project Draft Environmental Impact Report" (PDF). Valley Rail Sacramento Extension Project Draft Environmental Impact Report Volume II. September 2020. Archived (PDF) from the original on May 25, 2021. Retrieved December 19, 2020.
  42. ^ "Getting You There". San Joaquin Joint Powers Authority. Retrieved July 2, 2019.
  43. ^ "ACE® SATURDAY SERVICE TO BEGIN September 7, 2019" (Press release). San Joaquin Joint Powers Authority. August 21, 2019.
  44. ^ "SUPPLEMENTAL NOTICE OF PREPARATION OF AN ENVIRONMENTAL IMPACT REPORT: ACEforward – Notice of Additional Project Element – Niles Junction Connections" (PDF). San Joaquin Regional Rail Commission. May 9, 2016. p. 8.
  45. ^ SMA Rail Consulting (April 2016). "California Passenger Rail Network Schematics" (PDF). California Department of Transportation.
  46. ^ Luna, Henry J.; The Pacific Locomotive Association (2005). Niles Canyon Railways. Charleston, SC: Arcadia. ISBN  978-0-7385-2983-7.
  47. ^ "2020/2021 Work Program and Budget" (PDF). July 2020. p. 6.

External links

Route map:

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