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British Rail Class 398
British Rail Class 398
British Rail Class 398
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British Rail Class 398
Citylink
Class 398 on test at Abercynon in April 2025
In servicePlanned for Spring 2026[1]
ManufacturerStadler Rail
AssemblyStadler Rail Valencia SAU
Built atValencia, Spain
Family nameCitylink
Replaced
Constructed2020–present[2]
Number under construction36
Formation3 cars per unit
Fleet numbers398001–398036
Capacity252
(126 seated, 126 standing)
OwnersSMBC Leasing[3] and Equitix[4]
OperatorsTransport for Wales Rail
DepotsTaff's Well[5]
Specifications
Car body constructionStainless steel
Train length40.07 m (131 ft 6 in)
Width2.650 m (8 ft 8.3 in)
Floor height915 mm (36 in) at doors
DoorsDouble-leaf sliding plug
(1 per side per vehicle)
Wheel diameter740 mm (29 in)
Maximum speed62 mph (100 km/h)
Traction motors4 × TSA TMR 42-31-4,
each of 150 kW (201 hp)[6]
Power output600 kW (805 hp)
Electric system(s)25 kV 50 Hz AC overhead
Current collectionPantograph
UIC classificationBo′+2′2′+Bo′
Minimum turning radius25 m (82 ft)
Multiple workingWithin class
Track gauge4 ft 8+1⁄2 in (1,435 mm) standard gauge
Notes/references
Sourced from [7] except where otherwise noted.

The Class 398 Citylink[8] is a fleet of 36 tram-train multiple units being built for Transport for Wales Rail by Swiss rolling stock manufacturer Stadler Rail.

The units will be equipped with traction battery packages, allowing them to operate over non-electrified sections of track in addition to those with 25 kV 50 Hz AC overhead supplies.[2]

History

[edit]
Mock up of the outside of a Class 398 tram-train in early 2020
Mock up of the inside of a Class 398 tram-train in early 2020

The Wales & Borders rail franchise was awarded to KeolisAmey Wales in May 2018 and commenced on 14 October 2018.[9] The franchise award included a requirement that the operator perform a full replacement of its fleets;[10] as part of which process an order was placed with Stadler for delivery by 2023 of 36 tram-train units that would be capable of running on existing lines and also under battery power on the streets of Cardiff.[11]

All units are three cars and are able to be coupled together to form a six car unit. Each three car unit has a maximum passenger capacity of 256, units will have level boarding, space for bikes, wheelchairs and pushchairs. All seats will have access to plug and USB-A style sockets.[12][13]

The first unit to arrive in the UK was 398001 in May 2022, delivered from the Valencia works to the Rail Innovation & Development Centre in Melton, Leicestershire[14] for testing on the Old Dalby Test Track.

The first unit was delivered to Taff's Well depot on 21 March 2023.[15] The Welsh Government have stated that entry into service is planned for spring 2026.[1]

Operator

[edit]

Transport for Wales

[edit]

Transport for Wales Rail Class 398 units will operate services on the Rhondda, Merthyr and Cardiff City lines,[15] and the Cardiff Bay Branch.

Fleet details

[edit]
Class Operator Qty. Year built Cars Unit nos.
398 Transport for Wales Rail 36 2020–pres. 3 398001–398036

Named units

[edit]

Unit 398028 is named Myddfai[16]

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

British Rail Class 398

View on Grokipedia
from Grokipedia
The Class 398 is a class of 36 three-car battery-electric tram-trains manufactured by Swiss firm for , designed to provide seamless intermodal services on the electrified Core Valleys lines of the network. These units, numbered 398001 to 398036, feature a low-floor design with a total length of 40.07 metres, a width of 2.65 metres, and a height of 3.865 metres ( stowed), enabling compatibility with both street-level operations and standard railway . They are powered by a 25 kV AC overhead electrification system via a single on the intermediate , supplemented by onboard batteries for non-electrified sections, allowing maximum speeds of 97 km/h (60 mph) in heavy rail mode and 72 km/h (45 mph) in mode. Each unit comprises three s—a driving motor standard (DMS2) at one end, a trailer standard (PTS) in the middle, and another DMS1—offering a of 73.22 tonnes and seating for 126 passengers without onboard toilets. Introduced as part of the £1.2 billion project to enhance regional connectivity, the Class 398s are primarily allocated to the , , and Treherbert branches, running from Cardiff Central to destinations including , with services enabling a high-frequency "turn-up-and-go" timetable. Maintenance occurs at the purpose-built Light Maintenance Depot, a £100 million facility opened in November 2025. The first unit arrived at on 21 March 2023, with dynamic testing commencing in April 2025 on the Valley lines, including trial runs to stations such as Treherbert. As of November 2025, operational trials continue, with deliveries ongoing and the first units accepted for further preparation; driver training is structured in three stages to accommodate both heavy rail and signalling, and full passenger service entry is anticipated in 2026. The depot was officially opened by King Charles III on 14 November 2025. This deployment will facilitate the reallocation of existing Class 756 and Class 231 trains to other routes, improving overall network efficiency.

Development

Project background

The South Wales Metro project was initiated in 2016 by (TfW), established that year by the to oversee the modernization and integration of rail services across the . This initiative sought to transform the existing rail network by enhancing connectivity, increasing service frequency, and supporting economic regeneration in south-east . The rationale for the project centered on bridging connectivity gaps between the heavy rail system, which operates on 25 kV AC overhead , and lighter infrastructure suited to battery operation on non-electrified sections, such as underutilized branches. By incorporating capabilities, the aimed to enable seamless transitions between these systems, reduce reliance on diesel services, facilitate the closure or repurposing of low-usage lines, and promote sustainable to alleviate congestion and support environmental goals. Key milestones included initial feasibility studies in 2017, which evaluated options for electrification and network integration under the National Transport Finance Plan. In 2018, TfW confirmed the adoption of technology within the Wales and Borders franchise award, influenced by successful European implementations that allowed dual-mode operations on mixed rail environments. The supported a £200 million investment in 2019 toward as part of the broader £800 million commitment to new vehicles. was ultimately selected as the manufacturer for the Class 398 units. Following the , the £150 million with Stadler was finalized in March 2019, with commencing in 2020 at their plant in , . The first unit arrived in on 21 March 2023, and dynamic testing began in April 2025 on the Valley lines. As of November 2025, testing and certification continue ahead of passenger services in 2026.

Procurement and specification

In November 2017, Transport for Wales issued invitations to tender for 36 three-car tram-trains as part of the broader Wales and Borders rail service procurement, with a focus on interoperability between heavy rail and light rail operations, including compatibility with 25 kV AC overhead electrification and onboard batteries for non-electrified sections in the South Wales Metro project. Stadler Rail was selected as the preferred bidder in August 2018 following a competitive evaluation process, with their Citylink design chosen for its suitability to the required dual-mode capabilities. The full contract was awarded to Stadler in March 2019 for the supply of the 36 units, forming part of a larger order for 71 trains across the Wales and Borders network. The procurement specified three-car formations approximately 40 m in length, accommodating up to 252 passengers (126 seated) at standard density, a maximum speed of 100 km/h (62 mph) on heavy rail sections, and step-free access via a 915 mm floor height to enable seamless integration with street-running segments. The contract outlined initial deliveries commencing in 2023, with provisions for potential fleet expansion, and included the development of maintenance facilities at the new depot near to support long-term operations.

Design

Vehicle configuration

The British Rail Class 398 Citylink tram-trains are configured as three-car articulated units, consisting of two powered end cars flanking an unpowered intermediate trailer car, enabling efficient operation in both heavy rail and environments. Each unit measures 40.07 m in length, 2.65 m in width, 3.865 m in height ( stowed), and has an entrance height of 915 mm to support level or near-level boarding on compatible platforms. The is 73.22 tonnes. The interior layout emphasizes and flexibility, featuring double-leaf sliding-plug on each side of the cars for rapid passenger flow, spacious air-conditioned compartments with 126 seats including tip-up seats, and a total capacity of 252 passengers at a of 4 per . Dedicated spaces include six multifunctional areas for bicycles and two wheelchair-accessible positions equipped with fold-down tables, alongside priority seating and assistance buttons throughout. No onboard toilets are provided, with facilities available at stations at intervals of up to 14 minutes. Safety is integrated into the structural design through compliance with EN 15227 C-III standards, featuring energy-absorbing end structures made from high-strength to mitigate collision impacts. Additional features include a CCTV system and secondary that adjusts for passenger loading to maintain stable access. This configuration supports the units' dual-mode capabilities for seamless transitions between rail modes.

Dual-voltage and dual-mode features

The British Rail Class 398 tram-trains incorporate dual-mode electrical systems to enable operation across both heavy rail and light rail networks within the South Wales Metro, allowing seamless integration without the need for passenger transfers. The vehicles support 25 kV 50 Hz AC overhead electrification for heavy rail segments, collected via a single pantograph on the intermediate car, while onboard lithium-ion batteries handle power supply for light rail sections featuring discontinuous electrification. This configuration eliminates the complexity and cost of continuous overhead lines by using batteries to bridge gaps, with automatic pantograph raising and lowering at transition points to maintain service continuity. The propulsion setup employs four asynchronous traction motors (each rated at 150 kW) on the powered bogies of the end cars, delivering a total output of 600 kW to achieve maximum speeds of 100 km/h (62 mph) in heavy rail mode and 75 km/h (47 mph) in tram mode. Regenerative braking is integrated into the system, converting from deceleration into electrical power to recharge the batteries and improve overall . The 128 kWh supports operation over non-electrified stretches, providing a range of up to 10 km in battery-only mode, though practical application focuses on shorter gaps of a few kilometers between electrified zones. Control systems on the Class 398 are adapted for mixed operations, featuring compatibility with heavy rail signalling systems such as TPWS on electrified sections and line-of-sight driving modes for light rail street sections. Speed profiles are automatically adjustable based on the operational mode, capped at 100 km/h for heavy rail and lower limits for urban tram running to ensure safety. Mode transitions occur dynamically at interface points, with the control software managing power source handover and pantograph operations to minimize disruption, supported by battery reserves for brief unelectrified intervals.

Construction and testing

Manufacturing process

The British Rail Class 398 tram-trains are assembled at Stadler Rail's production facility in Albuixech, near , , which specializes in the Citylink family of vehicles. Following the contract award to in 2019 as part of the rolling stock procurement, production commenced with the fabrication of car body shells using lightweight structures, followed by assembly, electrical wiring installation, and interior outfitting in controlled manufacturing halls. Each three-car unit undergoes sequential build stages, incorporating UK-specific adaptations such as left-hand drive controls and compliance with standards during the integration phase. The first prototype unit was completed in early 2022 and underwent initial static testing before shipment. Deliveries to the began in May 2022, with the lead vehicle transported by road from a European port to a test site before arriving at the depot at , , in March 2023. The full fleet of 36 units is scheduled for progressive delivery through 2026, enabling phased introduction into service. Manufacturing adheres to the International Railway Industry Standard (IRIS) certification, ensuring rigorous across , production, and processes at the Valencia site. Additional compliance includes structural standards EN 12663 for load-bearing capacity (P-III category) and EN 15227 for crashworthiness (C-III category), with on-site inspections verifying integration of battery-hybrid power systems and tram-rail features.

Testing and certification

Testing of the Class 398 tram-trains commenced with static and dynamic trials at Stadler's manufacturing facility in , , beginning in 2022, prior to the first unit's delivery to the . These initial tests encompassed load trials to verify structural integrity under various payloads and systems integration checks for the dual-mode electric and battery operations, ensuring seamless transitions between overhead and battery power. The first Class 398 unit arrived at ' Taff's Well depot on 21 March 2023, marking the start of preparations for UK-based trials. Track testing on the Metro's Core Valley Lines began in April 2025, with unit 398005 conducting runs to Treherbert and , achieving speeds up to 100 km/h and demonstrating mode-switching capabilities on electrified sections. These trials focused on performance under operational conditions, including acceleration, braking, and compatibility with the discontinuous electrification system. Daylight testing commenced on 1 September 2025, with ongoing operational trials as of November 2025. The certification process is being handled by the Office of Rail and Road (ORR) in phased approvals, covering safety, technical standards, and requirements under the Railways (Interoperability) Regulations 2011. Interim approvals for testing have been granted, with full type approval anticipated by the end of 2025 to enable passenger service entry in spring 2026. A three-phase driver training program was initiated in June 2025, incorporating simulator-based familiarization, on-track competency building, and preparation for line-of-sight driving in segments. Key challenges during testing included ensuring signalling between heavy rail and sections, particularly for transitions to non-electrified or tram-style operations. These were addressed through software updates to the onboard control systems, enhancing compatibility with the upcoming signalling infrastructure and resolving integration issues identified in early dynamic tests.

Operations

Primary operator

Transport for Wales (TfW), a not-for-profit company wholly owned by the , has managed rail passenger services in Wales and bordering areas since taking over operations in 2018. As the primary operator of the Class 398 fleet, TfW is responsible for all aspects of unit maintenance, including repairs and servicing at its dedicated facilities, as well as crew training programs tailored to the tram-train's dual-mode capabilities. The Class 398 units are based at the purpose-built depot near , a £100 million facility that serves as the primary maintenance hub and control centre for the , enabling efficient storage, inspection, and preparation for service. The depot was officially opened by King Charles on 14 November 2025. Following certification, the units were handed over to TfW for operational familiarisation, with the depot supporting ongoing maintenance to ensure high availability. TfW has implemented a three-stage driver program for the Class 398, focusing on handling, dual-voltage operations, and integration with the existing fleet, including the related Stadler Class 756 units already in service on regional routes. This specialised equips crews to manage the units' battery-electric and modes seamlessly. As part of TfW's long-term public ownership model, the Class 398 fleet is integrated into broader investments, with TfW overseeing maintenance and any necessary refits to support service through the 2030s and beyond under funding commitments.

Intended routes and integration

The Class 398 tram-trains are primarily deployed on the branch lines of the Metro's Core Valleys network, including the , Coryton, , , and Treherbert () lines, with services extending through Queen Street to Central and alternating terminations at . These routes integrate with the broader Core Valleys Lines to provide through-services, allowing seamless connectivity across the valleys without the need for transfers at interchanges like Queen Street. Service patterns emphasize high-frequency operations to support metro-style reliability, with a target of 4 trains per hour (15-minute peak intervals) on the Treherbert, , , and branches, combining for over 20 trains per hour each direction through Cardiff Queen Street. The tram-train capability enables street-running on the approximately 2 km Butetown branch to , where 2 trains per hour from the Treherbert, , and lines will operate directly, extending the element of the network alongside heavier rail services spanning roughly 40 km of valleys infrastructure. Operating hours are extended, with last departures from outer branches shifting to around midnight to enhance evening accessibility. Integration with the electrified Core Valleys Lines, completed in preparatory phases by 2024, facilitates direct journeys that reduce travel times by 13-15 minutes from branches to (to approximately 49-50 minutes total) and by 16-20 minutes to , improving population access to key centers by 7% within 15 minutes, 22% within 30 minutes, and 48% within 45 minutes. This connectivity is projected to boost ridership, with early achievements showing a 27% increase on the route and an overall 8% modal shift from car use, supporting decarbonization through reduced emissions of approximately 178,000 tonnes of CO2 over 15 years. oversees these operations as the primary provider. The rollout is phased, with initial passenger services on the branch commencing in late 2025 following testing, and full integration across all Core Valleys routes achieved by spring 2026 to align with completion and depot readiness at . Further extensions, including enhanced street-running under Crossrail Phase 1, are planned for 2029.

Fleet details

Unit composition and numbering

The British Rail Class 398 units are formed of three cars per multiple unit, consisting of a Driving Motor Standard 2 (DMS2) car at one end, a Pantograph Trailer Standard (PTS) in the middle, and a Driving Motor Standard 1 (DMS1) car at the other end. This configuration provides a total length of approximately 40 metres and a tare weight of 73.22 tonnes per unit, enabling efficient operation on both heavy rail and light rail infrastructure. The design incorporates provisions for coupling two units to form a six-car train if demand requires extension in the future, using Scharfenberg couplers; though all 36 units in the fleet are identical with no sub-variants or build differences. Under the TOPS classification system, the units are numbered 398001 to 398036, reflecting the standard sequential allocation for new multiple units. As of November 2025, multiple units have been delivered to and are undergoing testing at depot, with the remaining units scheduled for completion and full fleet entry into passenger service by 2026.

Liveries and modifications

The Class 398 units feature the standard Metro livery, consisting of a white body with red and black accents. This scheme is applied during the manufacturing process at Stadler Rail's facility in , . The first units arrived in the UK in 2023 for initial preparations and were unveiled in a temporary manufacturer's finish before conversion to the operational TfW livery ahead of testing in 2025. All units, numbered 398001 to 398036, receive this standardized livery without initial variants. As newly constructed vehicles built to rail standards, the Class 398 fleet requires no major structural modifications, though standard features such as LED destination displays and integrated CCTV systems have been incorporated for compliance with operational regulations. No significant refits are anticipated in the near term, with the fleet designed for long-term service into the .

References

  1. https://tfw.wales/sites/default/files/2023-09/TfW%20CVL%20Vehicle%20Change%20proposal%20Class%20398%20v2.pdf
  2. https://tfw.wales/projects/metro/south-wales-metro/trains-and-stations
  3. https://www.railmagazine.com/news/fleet/2025/04/17/transport-for-wales-begins-testing-class-398-tram-trains-on-south-wales-metro
  4. https://www.railwaypro.com/wp/king-charles-opens-new-south-wales-metro-depot/
  5. https://www.modernrailways.com/article/three-stage-training-class-398s
  6. https://www.railadvent.co.uk/2025/10/transport-for-wales-get-visit-from-south-africas-minister-of-transport.html
  7. https://www.modernrailways.com/article/wales-blazes-trails-new-trains-on-the-rails
  8. https://tfw.wales/about-us/our-story
  9. https://www.gov.wales/sites/default/files/publications/2018-06/south-wales-metro-summary-brochure.pdf
  10. https://www.railway-technology.com/projects/south-wales-metro/
  11. https://www.bbc.com/news/uk-wales-33314634
  12. https://www.gov.wales/sites/default/files/publications/2017-12/national-transport-finance-plan-2017-update.pdf
  13. https://www.gov.wales/written-statement-update-procurement-wales-and-borders-rail-service-and-south-wales-metro-1
  14. https://www.walesonline.co.uk/business/business-news/200m-deal-buy-new-trains-16059421
  15. https://www.railwaygazette.com/modes/south-wales-metro-rolling-stock-order-confirmed/46974.article
  16. https://www.railwaypro.com/wp/stadler-to-deliver-71-new-trains-for-wales-borders/
  17. https://www.railwaygazette.com/uk/cardiff-valleys-class-398-tram-train-unveiled-at-innotrans/62443.article
  18. https://www.railway-technology.com/news/tram-train-south-wales-metro/
  19. https://www.stadlerrail.com/api/docs/x/4fd9bdcae0/citylink_transport-for-wales_en.pdf
  20. https://tfw.wales/sites/default/files/2023-10/ACC0001_A4EL_V5_FleetAccessSpecification.pdf
  21. https://tfw.wales/sites/default/files/2023-09/TfW%2520CVL%2520Vehicle%2520Change%2520proposal%2520Class%2520398%2520v2.pdf
  22. https://www.railengineer.co.uk/discontinuous-electrification-in-the-cardiff-valleys/
  23. https://tfw.wales/sites/default/files/2021-09/FOI%25202020-127%2520Various%2520Rolling%2520Stock%2520Queries%2520%255BENG%255D.pdf
  24. https://www.railway-technology.com/projects/stadler-citylink-tram-train/
  25. https://www.stadlerrail.com/en/solutions/references/citylink-transport-for-wales
  26. https://www.railvolution.net/news/first-class-398-tram-train-for-tfw-in-britain
  27. https://www.stadlerrail.com/api/docs/x/3a0eaa5458/srses-iso22163-en.pdf
  28. https://www.rail-suppliers.com/first-south-wales-metro-tram-train-arrives-at-new-depot/
  29. https://news.tfw.wales/news/first-south-wales-metro-tram-train-arrives-at-new-depot
  30. https://www.modernrailways.com/article/tram-trains-begin-testing-south-wales-metro-network
  31. http://www.britishtramsonline.co.uk/gallery2025/gallery38.html
  32. https://www.uktram.org/post/uktram-support-reflected-in-major-milestone-for-south-wales-metro-as-king-charles-opens-new-depot
  33. https://www.orr.gov.uk/sites/default/files/2023-11/transport-for-wales-rail-limited-section-22-7th-supplemental-agreement.pdf
  34. https://tfw.wales/transport-wales
  35. https://www.walesonline.co.uk/news/wales-news/trains-transport-for-wales-government-19145493
  36. https://tfw.wales/sites/default/files/2025-04/TfW-BP-2025_ENG.pdf
  37. https://news.tfw.wales/news/new-electric-tram-trains-in-testing-for-south-wales-metro
  38. https://tfw.wales/sites/default/files/2024-10/South%20Wales%20Metro%20Phase%202%20Evaluation%20Final%20Report%20-%20FINAL%20version%20ISSUED%20v3.0.pdf
  39. https://www.thepwi.org/wp-content/uploads/2024/03/2024-03-11_The-South-Wales-Metro-a-historical-perspective_A-Humpage.pdf
  40. https://www.modernrailways.com/article/new-trains-transform-tfw-fleet
  41. https://spotlog.org/locolist/class/UK/398
  42. http://www.britishtramsonline.co.uk/fleets/southwales.html
  43. https://www.modernrailways.com/article/first-tfw-398-arrives-taffs-well
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