The British Rail Class 172 is a diesel multiple unit (DMU) built as part of the Turbostar family of trains. It shares a common design heritage with related types, offering modular construction, driver cabs at both ends, and underfloor diesel power units. These characteristics make the Class 172 suitable for regional and suburban passenger services where electrification is not available.

Design and components

Like other members of the range, the Class 172 uses multiple unit principles: traction equipment is distributed beneath the floor of passenger vehicles, with driving cabs and standard couplings that permit units to work in multiple. Typical formations include two- and three-car sets, with interiors arranged for short-to-medium journeys. Passenger features commonly include seating in bays and airline layout, toilets, accessible doorways and passenger information systems.

Development and relation to other types

The Class 172 belongs to the broader Turbostar family and is closely related in concept to the Class 168, Class 170 and Class 171. All share a common lineage of lightweight construction and modular engineering developed for flexibility across a variety of UK routes. Differences between classes mainly concern internal fittings, coupling compatibility and some mechanical and braking details.

Operational role and uses

Class 172 units are used by several UK train operators on non-electrified regional and commuter lines. Their advantages include easy coupling for peak-time lengthening, suitability for frequent stops, and relatively straightforward maintenance. They are often selected where modern, reliable diesel multiple units are required to replace older rolling stock.

Notable features and distinctions

  • Part of a widely adopted modular family that simplified maintenance and fleet commonality.
  • Designed for short to medium-distance passenger comfort and quick turnaround.
  • Variants differ primarily in couplings and interior fitments to match operator requirements.

For technical details, operational history and operator lists consult specialised fleet guides and operator publications; the Class 172 is best understood in the context of the Turbostar family and its role replacing older DMUs on diesel routes. See also general information on diesel multiple units for background.