British Rail Class 171

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British Rail Class 171 Turbostar
Class 171 Hastings 13745676313.jpg
Southern 171721 at Hastings in 2014
171803 Standard Class Interior.jpg
The interior of Standard Class accommodation aboard a Southern Class 171
In service2003 - Present
ManufacturerBombardier Transportation
Built atDerby Litchurch Lane Works
Family nameTurbostar
Number built20 trainsets
Formation2/4 cars per trainset
Fleet numbers
  • 171 201 – 171 202
  • 171 401 – 171 402
  • 171 721 – 171 730
  • 171 801 – 171 806
  • 107 seats (2 Car)
  • 241 seats (4 Car)[1]
Car length23.62 m (77 ft 5 78 in)
Width2.69 m (8 ft 9 78 in)
Height3.77 m (12 ft 4 38 in)
Maximum speed100 mph (160 km/h)
  • Class 171/7: 90.41 tonnes (88.98 long tons; 99.66 short tons)
  • Class 171/8: 176.21 tonnes (173.43 long tons; 194.24 short tons)
Prime mover(s)One MTU 6R 183TD13H per car
Engine type13-litre 6-cylinder turbo-Diesel
Power output422 hp (315 kW) per engine
TransmissionVoith Hydraulic T211rzze
2 axles driven per car
Braking system(s)Air[1]
Safety system(s)AWS, TPWS
Coupling systemDellner coupling
Track gauge1,435 mm (4 ft 8 12 in) standard gauge

The British Rail Class 171 Turbostar is a type of diesel multiple-unit (DMU) train built by Bombardier Transportation (previously Adtranz) at its Derby Litchurch Lane Works in England, which is identical to the Class 170, except for the replacement of the BSI (Bergische Stahl Industrie) coupler with a Dellner coupling. This provision was made to allow emergency joining with Class 377 DC third-rail electric units, which Southern runs extensively on most lines. The vehicles work on the southern regions of the British railway system, operating services from London Bridge to Uckfield and from Eastbourne to Ashford International, these routes being unelectrified between Hurst Green Junction and Uckfield and between Ore and Ashford International, respectively.

The fleet is operated by Govia Thameslink Railway (GTR) for Southern services.


Class 170 on the left has a BSI 'Compact' coupler whereas Class 171 on the right has a Dellner coupler.

The Southern fleet is fitted with coupling devices (Dellner) different from other Turbostars, and is classified as Class 171 for this reason.[2] The four-car units were built with the new couplers, but Class 170 two-car units were fitted at a later date, and reclassified as Class 171/7 after the modification. Three more two-car units were later acquired, but these were built from new with the new couplers.

Southern gained the 170 392 unit from South West Trains. The coupler on this unit has also been changed to the Dellner type. The unit has been reclassified and renumbered from 170 392 to 171 730. This unit was first delivered carrying Southern livery and the number 170 727 (because SWT needed another 170 and it was cheaper to place another unit on the Southern order than place a new order). It never operated in this form and was transferred to South West Trains where it became 170 392.

These trains have electronic onboard displays and automated next station announcements.[3]


Class 171s have mainly standard-class seating plus either nine first-class seats on a two-car or 18 on a four-car; all first-class seats are reclining and have AC power sockets adjacent to the seats.

Standard-class seating includes five full-size folding seats in the area by the universal toilet on the DMOCL(W) vehicle. With these seats folded there is room for wheelchair users and bicycles. Each passenger door vestibule area also has two flip-down seats.

Standard Class 1st Class All seats
Normal Full-Folding Flip-Down Total
DMOCL(W) 38 5 4 47 9 56
DMOCL 50 0 4 54 9 63
DMOSL 64 0 4 68 0 68
MOS 74 0 4 78 0 78
Class 171/7
102 5 8 115 9 124
Class 171/8
236 5 16 257 18 275


4 car 171801.

Southern (previously named South Central) acquired an initial fleet of six two-car Class 171/7 and six four-car Class 171/8 units, to replace the slam-door Class 205 and Class 207 "Thumper" fleet.[4]

The first units were introduced in 2003 on the Marshlink Line from Ashford to Hastings and were extended in 2005 to Brighton, but in 2018 the service was cut back to Eastbourne due to overcrowding and a shortage of additional diesel stock. Services on the Oxted to Uckfield branch of the Oxted Line were later also transferred to Turbostar operation. Services from London Bridge to Uckfield went over to Turbostar operation in late 2004.

The Ashford-Eastbourne service, as well as peak-time Ashford-Rye and Ashford-Hastings shuttle services, are nearly always operated by the two-car Class 171/7; the four-car Class 171/8 units occasionally appear on the route during special events such as the Rye bonfire celebrations.

The Uckfield-London Bridge and Uckfield-Oxted services use both the two-car and the four-car units. These units are often coupled together, forming 6-car, 8-car or 10-car trains following platform extensions at Uckfield line stations.


Twelve units are scheduled to move to East Midlands Railway and be converted back to Class 170s with their carriage configuration also being changed to create 2 and 3 car units in 2021.[5][6]

Fleet details[edit]

First Class section of a Southern Class 171

Initial deliveries took place when the original 2-car units, at the time classified as Class 170/7, entered service in 2003, followed by the 4-car Class 171/8 units in 2004. At this time, the 2-car sets received their Dellner couplings and were reclassified as Class 171/7. In 2015, four 3-car Class 170/4 units were transferred to Southern from First ScotRail to enhance the fleet; two of these had the centre car removed and added to the remaining two, to form a pair of 2-car and a pair of 4-car units. With the addition of Dellner couplings, the new units were reclassified as Class 171/2 and 171/4.

Formation of 2-Car Class 171/7: DMOCL(W) + DMOSL
Formation of 4-Car Class 171/8: DMOCL(W) + MOS + MOS + DMOCL

Class Operator Number built Year built Cars per set Unit nos. Notes
Class 171/2 Southern 2 1999-2001 2 171201 - 171202 Converted from former First ScotRail Class 170 units in 2016.[7]
All units to transfer to East Midlands Railway and be converted back to Class 170s[5]
Class 171/4 2 4 171401 - 171402
Class 171/7 10 2003–2004 2 171721 - 171730[8] 6 units to transfer to East Midlands Railway and be converted to Class 170s,[5] 171730 formerly 170392
Class 171/8 6 2004 4 171801 - 171806[8] 2 units to transfer to East Midlands Railway and be converted to Class 170s[5]
Southern Class 171/2/7
Southern Class 171/4/8


  1. ^ a b Marsden, Colin J. (2007). Traction Recognition. Ian Allan Publishing. ISBN 978-0-7110-3277-4.
  2. ^ "Class 171". Southern Railway E-Group. Retrieved 1 May 2011.
  3. ^ "Southern on Train Facilities". National Rail. Retrieved 10 May 2011.
  4. ^ "Class 170". Southern Railway E-Group. Retrieved 1 May 2011.
  5. ^ a b c d A New Era for the East Midlands as Abellio starts its fifth franchise Today's Railways UK issue 214 October 2019 page 26
  6. ^ Replacements sought for 171s Rail issue 889 9 October 2019 page 29
  7. ^ Booth, Chris (December 2015). "The Turbostar Family". Today's Railways. Platform 5 Publishing (168): 38.
  8. ^ a b "Class 171 Fleet List". The Junction. Archived from the original on 5 February 2012.