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| British Rail Class 172 | |
|---|---|
| Name | British Rail Class 172 |
| Manufacturer | Bombardier Transportation |
| Family | Turbostar |
| Yearservice | 2010 |
| Numberbuilt | 39 |
| Formation | 2-car, 3-car |
| Maxspeed | 100 mph (160 km/h) |
British Rail Class 172 The British Rail Class 172 is a diesel multiple-unit train built for UK regional and commuter services. Introduced into service in 2010, it forms part of the Turbostar family and has been used by several train operating companys on routes across England, offering improved acceleration, ride quality and accessibility compared with older DMUs.
The Class 172 was developed by Bombardier Transportation as a member of the Turbostar family to replace ageing fleets such as British Rail Class 150, British Rail Class 153 and British Rail Class 158 units on services around London, the Midlands, and the East of England. Design objectives included compliance with the Disability Discrimination Act 1995 requirements for step-free access, reduced noise levels compared with Pacers (British Rail) units, and compatibility with existing Network Rail infrastructure. The prototype specification incorporated lessons from the Class 168 and Class 170 development programmes and involved collaboration with operators including London Overground and West Midlands Trains during the procurement and testing phases. Certification and acceptance testing were conducted under oversight from the Office of Rail and Road and with input from Rail Safety and Standards Board technical guidance.
Each set is formed as two-car or three-car diesel multiple units with aluminium bodywork and a B5000-style cab derived from earlier Turbostar designs. Power is provided by MTU Friedrichshafen engines coupled to hydraulic transmissions; units have a top speed of 100 mph and feature air suspension, electro-pneumatic braking and air-conditioning systems. The train control and diagnostics architecture borrows from Bombardier's Turbostar common designs, interfacing with AWS and TPWS safety systems used across the British railway network. Passenger accommodation includes 2+2 seating, accessible toilets meeting Rail Vehicle Accessibility Regulations 2010 and gangway connections compatible with multiple-working arrangements among Turbostar family units.
The Class 172 family comprises multiple variants specified for different operators: two-car and three-car formations with differences in internal layouts, door mechanisms and engine installations. Early orders produced units intended for use on inner-suburban services with increased standing capacity, while other batches were configured for longer-distance regional duties with tables and luggage provision similar to Class 170 interior standards. Some units were fitted with tripcock-style equipment and altered braking ratios to meet route-specific requirements on certain franchises, reflecting bespoke options ordered by companies such as London Overground and West Midlands Trains.
Class 172 units entered service with operators on franchises covering routes radiating from London Liverpool Street, Birmingham New Street and other regional hubs. Operators that have used the type include London Overground, West Midlands Trains, and other companies managing local and regional networks. They operate on services serving commuter stations, suburban corridors and rural branch lines, replacing older DMUs like Class 150 and supplementing units such as Class 168 and Class 170 on busy corridors. Deployment decisions were influenced by franchise awards, rolling stock leasing arrangements with ROSCOs, and strategic planning by the Department for Transport.
In service, the Class 172 demonstrated improved ride quality and lower noise emissions compared with older fleets, aiding operational performance on acceleration-limited stopping patterns on commuter routes. Reliability metrics were monitored by operators and regulators including Office of Rail and Road and Rail Safety and Standards Board, with some early teething issues addressed in maintenance programmes overseen by Bombardier depots and Network Rail engineering staff. Notable incidents involving Turbostar family units have informed safety reviews; investigations were conducted by the Rail Accident Investigation Branch when events occurred to establish causes and recommend mitigations.
Over their service life, Class 172 units have undergone interior refurbishments, software upgrades to control systems and mechanical modifications to improve fuel efficiency and emissions. Operators implemented changes to passenger information systems, CCTV installations, and seating arrangements influenced by feedback from Transport Focus and local authorities. Maintenance-led updates included suspension tuning, door control adjustments and engine calibration performed at authorised workshops and by Bombardier service teams to extend availability and meet evolving accessibility standards such as updates related to the Rail Vehicle Accessibility Regulations 2010.
With the ongoing evolution of UK rolling stock policy and electrification projects under programmes promoted by the Department for Transport and Network Rail, the future of diesel fleets like the Class 172 involves potential cascades, conversions or replacement by bi-mode or electric multiple units such as Class 769 conversions or new-build EMUs. Preservation interest in Turbostar family units has been limited compared with heritage diesel types, but individual vehicles might be candidates for preservation by groups associated with heritage railways and museums if withdrawn. Fleet life-extension, retrofit with cleaner propulsion technologies, or reallocation across franchises remain plausible outcomes as operators plan rolling stock strategies in response to franchise changes and environmental targets set by UK authorities.
Category:Diesel multiple units of Great Britain Category:Bombardier Transportation rolling stock