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Alstom PL42AC
Alstom PL42AC
Alstom PL42AC
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PL42AC
New Jersey Transit PL42AC #4029 at Convent Station
Type and origin
Power typeDiesel-electric
BuilderAlstom, EMD
ModelPL42AC
Build date2003–2006[citation needed]
Total produced33
Specifications
Configuration:
​
 • AARB-B
 • UICBo′Bo′
Gauge4 ft 8+1⁄2 in (1,435 mm) standard gauge
Wheel diameter42 in (1,067 mm)
Length69 ft 10 in (21.29 m)
Width10 ft 8 in (3.25 m)
Height15 ft 5 in (4.70 m)
Loco weight287,000 lb (130,000 kg)[1][2]
Fuel capacity2,250 US gal (1,870 imp gal; 8,500 L)
Prime moverEMD 16-710G3B-T1
Engine typeV16, two-stroke diesel
AlternatorTA-17
Head end power800 kW (1,100 hp)
Cylinders16
Performance figures
Maximum speed100 mph (160 km/h)[1]
Power output
  • At alternator: 4,200 hp (3.1 MW)
  • At rail: 3,620 hp (2.70 MW) MAX with HEP on
Tractive effortstarting: 69,975 lbf (311.26 kN)
continuous: 27,000 lbf (120 kN) [clarification needed]
Career
OperatorsNJ Transit
Numbers4000–4032[3]
Sources:[2][4] except where noted

The Alstom PL42AC is a class of four axle B-B diesel-electric locomotive designed by Alstom in association with GM-EMD. 33 were built between 2003 and 2006 for NJ Transit Rail Operations.

Description

[edit]

The PL42AC is a diesel-electric 4-axle locomotive built by Alstom with the 16-710G3B prime mover for New Jersey Transit. The first two locomotives were manufactured at the Meinfesa plant in Valencia, Spain in 2003.[5] The 31 following units were assembled at the Alstom Transport plant in Hornell, New York in 2004,[6] and were produced through early 2006. The power rating of the PL42AC locomotives is 4,200 hp (3.1 MW) total for tractive effort and head-end power. The locomotive has a design similar to the GE Genesis, mainly because both PL42AC and Genesis series locomotives were designed by industrial designer Cesar Vergara.[7]

This locomotive uses IGBT technology with precise traction computers for tractive effort. The PL42AC has 800 kilowatts head-end power and WABCO's EPIC II braking system, along with an E-7 wheel slide device, made by Wabtec, preventing flats spots on the wheels through software and hardware.

It has an Intelligent Display Unit (IDU) based on Bombardier Transportation technology from which an engineer or technician can view data or download events and faults from the previous weeks or months. The technician can do a host of tests from the IDU to determine if a specific system is operating correctly.

The PL42AC uses computer hardware and software to control functions and to protect the engine. For example, if the on-board computer detects too little oil in the system, it will shut down the engine to avoid damage.

Accidents

[edit]

On December 19, 2025, engine 4008 was involved in a head on collision with another train on the Montclair-Boonton Line at the Bay Street station, resulting in damage to the nose.[8]

Future

[edit]

In July 2020, NJ Transit announced that older locomotives in the PL42AC fleet will be replaced by additional ALP-45A dual mode locomotives, due to the PL42AC's unreliability and inability to be upgraded to meet new Environmental Protection Agency standards.[9] Of the 33 units, 23 are slated for replacement, while the remaining 10 will receive a light overhaul for continued service.[10]

As of December 2025, fewer than 20 units are considered active and fit for service, while the remaining have been sidelined for prolonged periods of time due to significant maintenance issues.

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Alstom PL42AC

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from Grokipedia
The PL42AC is a four-axle B-B configuration diesel-electric locomotive designed and built by Transportation specifically for Transit (NJT) operations on non-electrified lines. Powered by a 4,200 horsepower EMD 16-710G3B-T2 16-cylinder prime mover, it delivers up to 3,680 horsepower for traction and features AC traction motors for efficient passenger service. A total of 33 units, numbered 4000–4032, were produced between 2004 and 2006 to bolster NJT's diesel fleet capacity amid growing ridership demands. Procured under a contract awarded to in late , the PL42AC class was a design incorporating EMD's proven engine technology with Alstom's electrical systems, including IGBT-based for improved reliability and lower emissions compared to NJT's older fleet. The locomotives were primarily assembled at Alstom's facility in , following initial design work in , , with the first units entering testing in 2003 before full revenue service by 2005. Weighing approximately 131 tonnes and capable of speeds up to 100 mph (160 km/h), they measure 70 feet in length and include features like a 2,250-gallon fuel capacity to support extended runs on NJT's diesel routes, such as the and . Despite their advanced specifications at the time, the PL42ACs' unique design—exclusive to NJT—has posed maintenance challenges, including limited parts availability and higher costs for specialized components like the custom AC propulsion system. As of November 2025, most of the 33 units remain in active service, though NJT initiated plans in 2020 for partial retirement, aiming to replace 23 units with newer dual-mode ALP-45DP (including ALP-45A variants) locomotives from Bombardier (now Alstom) while overhauling 10 units to meet emissions standards and improve fleet interoperability. This transition, delayed from initial timelines, reflects broader efforts to modernize NJT's approximately 175-locomotive fleet for enhanced reliability on its 12-line rail network, part of a system serving over 800,000 daily passengers across bus and rail services.

Background and Development

Origins and Procurement

In the early 2000s, Transit's expanding rail operations required additional diesel locomotives to support service on its extensive non-electrified lines, including routes like the Atlantic City Line and portions of the Morris & Essex Lines, where the aging fleet struggled with reliability and capacity demands. To address these needs, the approved the of 33 new diesel-electric passenger locomotives in September 2001, aimed at replacing older units such as the models that dated back to the and . The contract was awarded to Transportation Inc., in collaboration with ' Electro-Motive Division, for a total value of 188 million euros (approximately $163 million USD at the time), with an option for up to five additional units. Funding for the procurement came from a mix of state resources through the Transportation Trust Fund and federal grants administered by the , reflecting broader efforts to modernize infrastructure. Following the , initial planning and phases advanced through 2002, with manufacturing commencing in 2003 at Alstom's facility in , and the first units entering testing and delivery in 2004.

Design Collaboration and Production

The of the PL42AC resulted from a collaboration between Alstom's engineering team in , , and Electro-Motive Division (GM-EMD), focusing on integrating the EMD 16-710G3B prime mover into Alstom's AC traction architecture. This partnership leveraged Alstom's expertise in electrical systems and GM-EMD's established diesel engine technology to create a passenger compliant with emerging EPA Tier I emissions standards. Key to the design process was industrial designer , who led the exterior and structural styling, drawing on his prior experience with the locomotive to adapt a streamlined, four-axle B-B configuration optimized for commuter service efficiency and . Vergara's influence emphasized a lightweight carbody and integrated cab design to enhance and operator comfort, while maintaining compatibility with North American rail standards. The overall concept prioritized a balance between high generation and traction performance for push-pull operations. Production commenced with two prototypes fully constructed at Alstom's Meinfesa facility in , , in 2003, allowing for initial testing and validation of the integrated systems. The remaining 31 units were assembled at Alstom's , plant from 2004 through early 2006, utilizing kits shipped from to incorporate local U.S. components and finalize assembly for the North American market. This hybrid manufacturing approach reduced lead times and supported between Alstom's European and American operations. Notable innovations included the adoption of insulated gate bipolar transistor (IGBT) technology in the traction inverters for precise control of AC motors, enabling smooth acceleration and . Additionally, the locomotives integrated WABCO's EPIC II electropneumatic braking system, which provided advanced air brake modulation and anti-wheel slide protection to minimize wheel flat risks during frequent stops. These features underscored the project's emphasis on reliability for high-density commuter routes.

Technical Design

Mechanical and Electrical Features

The PL42AC utilizes a B-B with four axles to achieve balanced weight distribution across the , enhancing stability and maneuverability on urban rail corridors. The 's body adopts a sleek all-steel construction with a streamlined profile akin to the series, offering dimensions of 69 ft 10 in in length, 10 ft 8 in in width, and 15 ft 5 in in height to optimize and clearance for passenger service. Electrical systems incorporate the Intelligent Display Unit (IDU) for real-time diagnostics, fault monitoring, and data logging to support efficient operation and maintenance. Complementing this is the E-7 device from , which employs software and hardware integration to mitigate wheel slip and prevent flat spots during braking. Safety and auxiliary features include (HEP) generation rated at 800 kW to supply heating, lighting, and other train amenities, a capacity of 2,250 US gallons for extended range, and compatibility with standard gauge track measuring 4 ft 8½ in. The core diesel engine is an EMD 16-710 series prime mover, integrated to drive both and auxiliary functions.

Powertrain and Performance Specifications

The PL42AC employs a diesel-electric centered on an EMD 16-710G3B prime mover, a 16-cylinder, designed for high reliability in passenger service. This engine drives a main that generates the locomotive's total power output, enabling efficient conversion to electrical energy for and auxiliary systems. The power ratings reflect the locomotive's dual role in providing traction and (HEP): the main alternator produces 4,200 hp overall, but when delivering 800 kW of HEP to support passenger car amenities, 3,620 hp remains available for traction, ensuring balanced performance during typical commuter operations. This configuration prioritizes consistent power delivery under varying loads, with the engine tuned to meet EPA Tier 1 emissions standards. Traction is achieved through four Alstom AC traction using (IGBT) inverters for improved efficiency and precise control of power delivery. These , combined with the locomotive's total of 288,000 lb, provide strong for accelerating trains, supporting a top speed of 100 mph. The IGBT inverters enhance power control by reducing switching losses and enabling smoother application across speed ranges. The braking system integrates , which regenerates energy during deceleration by using the traction motors as generators, with a pneumatic air system managed by WABCO's EPIC II . This setup allows for blended braking, optimizing friction and dynamic elements to minimize wear while maintaining safe stopping distances; the 288,000 lb weight further aids during braking maneuvers.

Operational History

Introduction to Service

The PL42AC locomotives began entering Transit's fleet in 2004, marking the start of a multi-year delivery process for the 33-unit order numbered 4000 through 4032. The initial units arrived following initial assembly and testing preparations, with the complete fleet achieving full operational status by early 2006. This timeline aligned with Transit's efforts to modernize its roster for operations. Prior to revenue operations, the PL42AC units underwent rigorous testing and certification phases to ensure compatibility with New Jersey Transit's infrastructure, particularly on non-electrified routes such as the and . These phases included evaluations of traction, braking, and signaling systems to meet federal and state safety standards for passenger service. The locomotives' design features, including AC traction enabling top speeds of 100 mph, facilitated successful certification for high-demand commuter corridors. The PL42AC fleet was initially assigned to push-pull commuter service, hauling bilevel and single-level coaches on New Jersey Transit's diesel lines while progressively replacing aging locomotives. The first revenue service occurred in 2005, with early operations integrating the new units alongside Bombardier BiLevel cars to enhance capacity on key routes. This deployment represented a significant milestone in Transit's fleet renewal, improving efficiency for daily commuter traffic.

Reliability and Maintenance Challenges

The PL42AC locomotives have encountered significant reliability challenges since entering service, primarily due to their aging infrastructure and unique design, which has complicated parts and repairs. Mechanical failures in the PL42AC fleet have contributed to NJ Transit's broader decline in performance. These issues have resulted in substantial downtime and frequent service delays without any reported major accidents involving the fleet. Maintenance efforts for the PL42AC have focused on condition-based programs to extend and mitigate failures, including a 2009 initiative with Transportation's subsidiary that involved teardowns of sample units, revealing that full overhauls were not immediately required but highlighting the need for proactive diagnostics across the 33-unit fleet. Routine overhauls and inspections are conducted at NJ Transit's Meadows Maintenance Complex in , as part of broader state-of-good-repair projects aimed at optimizing performance and reducing costs. However, the locomotives' custom design has driven up maintenance expenses, with rehabilitation costs approaching $3 million per unit, leading to scaled-back plans by 2020 where only 10 PL42ACs received reduced overhauls while the remainder were slated for replacement. An additional challenge emerged with environmental regulations, as the PL42AC's Tier 1 emissions compliance, achieved at initial production in 2005, could not be upgraded to meet the EPA's stricter Tier 4 standards by 2020, rendering the fleet non-compliant for continued long-term use and accelerating retirement discussions. This limitation, combined with high unreliability, has prompted to prioritize newer dual-mode locomotives capable of Tier 4 adherence, further straining maintenance resources for the existing PL42ACs. As of November 2025, while partial retirements have been initiated (replacing at least 10 units with ALP-45DP locomotives), many PL42AC units continue to operate on diesel routes such as the .

Fleet and Future

Current Status and Operators

As of 2025, New Jersey Transit Rail Operations operates the remaining Alstom PL42AC locomotives, with 29 units (numbered 4000–4032) in active service, all based in New Jersey. These locomotives are assigned to diesel-only commuter routes, where they continue to haul passenger trains despite ongoing fleet modernization efforts. Some units have received light overhauls to extend their operational life, allowing them to remain in active duty. The overall fleet condition reflects a transitional phase, with several units retired or slated for near-term due to age and performance limitations, though others continue in daily service amid delays for replacements. No PL42AC units have been retired to museums, preserved elsewhere, or exported; all remain under Transit's retention.

Replacement and Retirement Plans

In July 2020, announced plans to replace older units in its fleet of 33 PL42AC diesel locomotives with additional ALP-45DP dual-mode locomotives manufactured by (now ), citing the PL42AC's chronic unreliability, advancing age, and inability to be upgraded to meet EPA Tier 4 emissions standards. The initial purchase approved at that time included eight ALP-45DP units at a cost of up to $70 million, enabling the retirement of some PL42AC locomotives to improve overall fleet reliability and reduce emissions by an estimated 52 tons annually. Progress on the replacement continued with NJ Transit's Board of Directors approving the purchase of 12 additional ALP-45DP locomotives in May 2025, at a cost of up to $203.9 million, bringing the total ALP-45DP fleet to 72 units. These acquisitions form part of a broader strategy to phase out older diesel-only locomotives like the PL42AC, with full fleet modernization targeted for completion by 2031 to enhance efficiency and environmental compliance. The ALP-45DP's dual-power capability—operating in both diesel and electric modes—directly addresses the PL42AC's limitations as a diesel-only , allowing seamless service on NJ Transit's electrified lines without mode changes. This integration supports the ongoing retirement of the PL42AC fleet by providing versatile, Tier 4-compliant alternatives that align with network demands.

References

  1. https://www.nj.com/news/2020/07/nj-transit-buying-70m-worth-of-new-locomotives-approves-264m-infusion-from-state.html
  2. https://www.trains.com/trn/news-reviews/news-wire/digest-nj-transit-board-approves-locomotive-purchase/
  3. https://www.railwayage.com/news/njt-taps-alstom-subsidiary-for-locomotive-repair-program/
  4. https://www.mainlinediesels.net/index.php?nav=1000806&lang=en
  5. https://www.nj.com/traffic/2021/04/gov-murphy-checks-out-the-little-engine-that-could-improve-nj-transits-reliability.html
  6. https://www.instagram.com/p/DQ8CI3bjPoX/
  7. https://www.railwayage.com/wp-content/uploads/2020/03/njt_commuter_rail_fleet2014.pdf
  8. https://www.alstom.com/press-releases-news/2001/9/ALSTOM-to-provide-passenger-locomotives-to-New-Jersey-transit-in-the-USA-20010924
  9. https://www.transit.dot.gov/sites/fta.dot.gov/files/docs/Thursday_PM_-_Garino_-_FTA_SOGR_Roundtable_Chicago_2010.pdf
  10. http://www.mainlinediesels.net/index.php?nav=1000806&lang=en
  11. https://www.railwayage.com/passenger/intercity/cesar-vergara-recipient-of-railway-age-graham-claytor-award/
  12. http://wilmingtonnrhs.com/newsletters/2002sep.htm
  13. https://www.researchgate.net/publication/282345080_Comparison_of_Over-the-Rail_and_Rail_Yard_Measurements_of_Diesel_Locomotives
  14. https://locomotive.fandom.com/wiki/Alstom/EMD_PL42AC
  15. https://metro.fandom.com/wiki/New_Jersey_Transit_rail_operations
  16. https://www.railpictures.net/viewphoto.php?id=119618
  17. https://www.nj.com/news/2025/04/nj-transit-rail-reliability-is-plummeting-what-this-means-for-your-commute.html
  18. https://www.railwayage.com/passenger/commuterregional/jersey-transit-strong/
  19. https://www.njtransit.com/press-releases/nj-transit-purchase-eight-additional-dual-powered-locomotives
  20. https://www.njtransit.com/press-releases/nj-transit-continues-commitment-modernize-rail-fleet
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