Rolling stock › In serviceData updated
Class 231 FLIRT
Stadler's four-car diesel FLIRT, with its engines in a short power pack car in the middle of the train, away from the passengers. Transport for Wales's 11 work from Rhymney to Cardiff and Barry Island, Maesteg to Ebbw Vale, and Cardiff to Cheltenham; they are to be fitted with pantographs and become bi-modes.
Drawing to come
- Type
- Diesel-electric multiple unit
- Builder
- Stadler, Bussnang (Switzerland)
- Built
- 2021–2022
- In service
- since 2023
- Operators
- Transport for Wales
- Formation
- 4 passenger cars and a short power pack car: 80.7 m over couplings
- Trains in fleet
- 11
- Fleets
- Transport for Wales: 11
- Top speed
- 90 mph
- Power
- Diesel-electric: four Stage V diesel generator sets in the power pack car, 1,920 kW (1,500 kW at the wheel)
- Train length
- 80.70 m
- Car height
- 3.915 m
- Car width
- 2.72 m
- Profile
- main-line
- Air-conditioned
- Yes
- Seats per train
- 170
- Total capacity
- 170 seats, 34 tip-up and 188 standing (Stadler); 204 seats including tip-ups (TfW)
- Status
- In service: 11 units, maintained at Canton, Cardiff. In June 2026 TfW confirmed that pantographs will be fitted over the coming years. Owned by SMBC Leasing and Equitix.
Car types
| Code | Car | Length | Doors per side |
|---|---|---|---|
| DMSO | Driving motor standard open (DMSO), over the motor bogie | 2 double | |
| TSO | Trailer standard open (TSO) | 1 double | |
| PP | Power pack car (PP): four diesel generator sets, with no doors or seats | ||
| TSOW | Trailer standard open with wheelchair spaces and toilet (TSOW) | 1 double |
Sources
- FLIRT diesel-electric multiple unit, Transport for Wales (data sheet FWBDMU0423e), Stadler, April 2023 (11 units; 80,700 mm; width 2,720 mm; height 3,915 mm; floor 960 mm; 170 seats, 34 tip-up, 188 standing; 1,920 kW diesel, 1,500 kW at wheel; 90 mph; Bo'2'2'2'2'Bo')
- CVL Vehicle Change notice: Class 231, Core Valley Lines (except Cardiff Bay), entry into service, Amey Infrastructure Wales for Transport for Wales Rail Ltd, 8 September 2022 (formation DMSO1-TSO-PP-TSOW-DMSO2; doors; 154.3 t; 90 mph; maintained at Canton; first unit delivered November 2021)
- Transport for Wales launches Class 231 Flirt DMUs, Railway Gazette International (Rail Business UK), 29 March 2023 (launch at Caerphilly, 29 March 2023; first on the Rhymney line, replacing Class 769s)
- A guide to our fleet of trains: fleet accessibility specifications (V3, updated June 2026), Transport for Wales, June 2026 (11 units; 170 seats and 34 tip-up; routes (June 2026))
- Transport for Wales confirms '231' fleet will become bi-modes, RAIL, 3 June 2026 (pantographs to be fitted to all 11, confirmed June 2026)
- Case study: Wales & Borders, commercial and contract management, Apex Rail, accessed 7 October 2026 (owned by SMBC Leasing and Equitix)
- British Rail Class 231, Wikipedia, accessed 7 October 2026 (first passengers 18 January 2023; bodyshells from Szolnok (last resort))
unverified car lengths: not found for the Class 231; Stadler gives only the 80.7 m unit. Greater Anglia's Class 755/4, the same FLIRT UK design and length, has 21.05 m driving cars, 15.70 m trailers and a 7.2 m power pack car (the site's 755 record), which may be the same, doors: two pairs a side on each driving car and one on each trailer (TfW's 2022 vehicle change notice); their positions aren't given, build years: TfW received the first unit in November 2021 and expected the eleventh in September 2022 (2022 notice); Wikipedia says the bodyshells were made at Szolnok, Hungary, first passengers: Wikipedia, citing The Railway Magazine, gives 18 January 2023; the formal launch was on 29 March 2023 (Railway Gazette), owners: SMBC Leasing and Equitix, from a consultant's case study (Apex Rail)