UK's first tri-mode trains enter service as Transport for Wales' '756s' make passenger debut

Transport for Wales’ (TfW) new electric ‘tri-mode’ trains have begun to enter service as part of the South Wales Metro.

The new Class 756 units, which are the first in the UK to be able to run on either electric, diesel or battery power, will first be used on the Merthyr Tydfil and Aberdare lines, followed by the Treherbert route. They made a low-key passenger debut last week.

A total of 17 four-car units and seven three-car trains are being delivered to TfW, which aims to have 14 running by spring 2025.

The Stadler-built trains, which are similar to Greater Anglia’s ‘755’s, will take power from overhead catenary on lines to the north of Cardiff, while using diesel to the south, although that is limited to specific areas to keep emissions to a minimum.

TfW has said that from late 2025 the ‘756s’ will start to appear on the Rhymney and Vale of Glamorgan lines as they replace Class 150s, 153s and 769s.