British Rail Class 171

Bombardier Transportation

Industry	Rail vehicle manufacturing
Headquarters	Derby , England
Products	British Rail Class 171 Turbostar diesel multiple units

British Rail Class 171 Turbostar

The British Rail Class 171 Turbostar is a diesel-hydraulic multiple unit passenger train constructed by Bombardier Transportation at the Derby Litchurch Lane Works facility in England. It bears a strong resemblance to the Class 170 but is primarily distinguished by its use of a Dellner coupler rather than the BSI coupler. This feature enables emergency coupling compatibility with Class 377 DC third-rail electric trains, which are widely operated by Southern.

The Class 171 units operate on Southern’s routes across southern England, including services from London Bridge to Uckfield and Eastbourne to Ashford International. These lines contain non-electrified segments between Hurst Green Junction and Uckfield, as well as between Ore and Ashford International. The fleet is managed by Govia Thameslink Railway under the Southern brand.

Design

The presence of Dellner couplers sets this fleet apart from other Turbostar variants, justifying its separate classification as Class 171. Initially, four-car units were manufactured with Dellner couplers, while some two-car Class 170 units were subsequently retrofitted with these couplers and re-designated as Class 171/7. Furthermore, three additional two-car units were delivered equipped with Dellner couplers from new.

Southern acquired unit 170392 from South West Trains, modifying its coupler to the Dellner standard and renumbering it as 171730. Although this unit was originally delivered in Southern livery as 170727, it never entered service under that number before being transferred.

These trains feature electronic onboard display systems alongside automated announcements for upcoming stations, improving passenger information delivery.

Operations

Southern initially purchased six two-car Class 171/7 sets and six four-car Class 171/8 units to replace the obsolete slam-door Class 205 and Class 207 "Thumper" trains.

The units were first introduced in 2003 on the Marshlink Line connecting Ashford International and Hastings. This service was extended to Brighton in 2005 but later scaled back to Eastbourne in 2018 due to capacity constraints caused by overcrowding and limited diesel rolling stock availability. Turbostar units also took over operations on the Oxted to Uckfield branch line, with London Bridge to Uckfield services transferring in late 2004.

Two-car Class 171/7 sets mainly operate on the Ashford-Eastbourne route and provide peak-time shuttles between Ashford-Rye and Ashford-Hastings. Four-car Class 171/8 units are deployed during special events. Both configurations are utilized on Uckfield-London Bridge and Uckfield-Oxted routes, frequently coupled together to form longer trains—up to ten carriages—following platform lengthening projects on the Uckfield line.

Future

As of August 2022, Southern's fleet comprised 20 trainsets: twelve two-carriage and eight four-carriage formations. In September 2022, two Class 171/2 and two Class 171/4 sets were reconfigured back into their original three-carriage arrangements, returned to Eversholt Rail Group, and leased out to East Midlands Railway (EMR). Three of these were transferred to EMR for conversion back into Class 170 units, while one remained on sub-lease with Southern. By December 2022, Southern was expected to operate a fleet consisting of four two-carriage and thirteen three-carriage sets.

Fleet details

The initial batch of deliveries commenced in 2003 with two-car sets designated as Class 170/7, followed by the introduction of four-car Class 171/8 units in 2004. Subsequently, the two-car formations were equipped with Dellner couplings and reclassified as Class 171/7. In 2015, four three-car Class 170/4 units acquired from First ScotRail underwent modifications: two units had their middle cars removed and these were added to the other two units, resulting in the creation of two two-car and two four-car sets. After fitting Dellner couplers, these were redesignated as Class 171/2 and 171/4.

In September 2022, units numbered 171202, 171401, and 171402 were transferred to East Midlands Railway and renumbered to 170422, 170423, and 170424 respectively.

Typical formation of a two-car Class 171/7 unit consists of: DMOCL(W) + DMOSL A four-car Class 171/8 unit is formed as: DMOCL(W) + MOS + MOS + DMOCL

Class	Operator	Quantity	Year constructed	Cars per set	Unit numbers	Remarks
171/2	Southern	1	1999-2001	3	171201	Converted in 2016 from a former First ScotRail Class 170 set.
171/7		4	2003-04	2	171727 - 171730	Unit 171730 was previously numbered 170392.
171/8		12	2003-04	3	171801 - 171812	Originally, units 171801 - 171806 were four-car formations but had one intermediate vehicle removed by December 2022; these removed cars were then incorporated into originally two-car sets 171721 - 171726 to form units numbered 171807 - 171812.