A fleet of 36 tram-trains costing more than £200m remains largely out of passenger service, with Transport for Wales (TfW) saying full deployment across the South Wales Valleys may not be complete until the end of 2027. The original target was 2022.
The trains are part of the £2bn South Wales Metro project. Data obtained by the BBC shows that 16 have passed the required statutory tests, while the other 20 have yet to complete checks for operation on the UK rail network. Testing on some vehicles began in 2024 and has taken between six weeks and two years.
Six trains, each valued at about £8m, are currently undergoing passenger testing. TfW has occasionally withdrawn them because of early reliability problems, which the operator has linked to software issues. Chief executive James Price said the fleet would not be introduced in large numbers until it could meet the company’s reliability expectations.
The Class 398 Citylink trains were ordered from Swiss manufacturer Stadler in 2018, and the first arrived in Wales in March 2023. They are designed to run on both streets and railway lines. TfW says the fleet’s software controls many of the trains’ functions and that updates could allow improvements to be applied across the vehicles.
The delay also affects plans to increase services from two to four trains an hour between Cardiff and Aberdare, Merthyr Tydfil and Treherbert. TfW says it expects the higher frequency by the end of 2027, alongside the full rollout. The operator says crew training and signalling work at Cardiff Queen Street station are among the remaining requirements.
Price said the arrival of new Class 756 trains on the valley lines in 2024 took priority, and that they could not test the tram-trains against the original timetable. He described the delays as frustrating but said the operator wanted trains that worked reliably before expanding passenger service.
TfW also attributed part of the delay to the completion of electrification infrastructure, which it said was finished in March after setbacks linked to Covid and supply-chain impacts from the War in Ukraine. Although the network is fully electrified, only about two-thirds has overhead wires; the trains use onboard batteries on sections without them. TfW says this approach saved about £400m and years of work.
Rail engineer Gareth Dennis said the project combines several technologies, including street operation, rail travel, batteries and sections without continuous overhead electrification, making the trains complex to test. Stadler said it was working with TfW to resolve minor issues and that software updates and other refinements were part of introducing the fleet.
Welsh opposition politicians have criticised the number of trains still out of service. The Welsh government said TfW remained on target to complete the rollout by the end of 2027 and said the new trains would eventually enable more frequent services across the valleys and Cardiff.
Sources: BBC News UK.