British Rail Class 171

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British Rail Class 171 Turbostar
171727 Southern.JPG
Southern Class 171/7, no. 171 727 at Lewes railway station, with a service from Brighton to Ashford International
Interior of a Class 171 featuring a customer information system display
In service 2003 - Present
Manufacturer Bombardier Transportation, Derby, UK
Family name Turbostar
Constructed 2003 - 2004
Number built 16 trainsets
Formation 2/4 cars per trainset
Fleet numbers
  • 171 721 - 171 730
  • 171 801 - 171 806
  • 107 seats (2 Car)
  • 241 seats (4 Car)[1]
Operator(s) GTR Southern
Car length 23.62 m (77 ft 6 in)
Width 2.69 m (8 ft 10 in)
Height 3.77 m (12 ft 4 in)
Maximum speed 100 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 183TD diesel per car
Power output 422 hp (315 kW)
Transmission Voith Hydraulic T211rzze
2 axles driven per car
Braking system(s) Air[1]
Safety system(s) AWS, TPWS, GSM-R
Coupling system BSI coupling replaced by Dellner coupling
Track gauge 1,435 mm (4 ft 8 12 in) standard gauge

The Class 171 Turbostar is a type of diesel multiple unit (DMU) train built by Bombardier Transportation (previously ADtranz) at its Litchurch Lane Works in Derby, 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. The vehicles work on the southern regions of the British railway system, operating services from London Bridge to Uckfield and from Brighton to Ashford International, these routes being unelectrified between Hurst Green and Uckfield and Ore and Ashford International, respectively.

The fleet are 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 170 392 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 automated station announcements and onboard displays.[3] [clarification needed]


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 mains 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 TOTAL
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


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 its ageing Class 205 and Class 207 "Thumper" fleet.[4]

The first units were introduced in 2003 on the Ashford to Hastings "Marshlink Line" (now running further to Brighton). 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-Brighton 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 or 8-car trains.

Fleet details[edit]

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.
Class 171/7 Southern 10 2003–2004 2 171 721 - 171 730[5]
Class 171/8 6 2004 4 171 801 - 171 806[5]

In 2015, Four Class 170/4 units operated by First ScotRail came off lease following the transfer of the Scottish franchise to Abellio. These units were subsequently transferred to Southern to strengthen services on the Uckfield line, with the intention that they be converted to Class 171s.[6]

Class 171 Southern Diagram.PNG


  1. ^ a b Marsden, Colin J. (2007). Traction Recognition. Ian Allan Publishing. ISBN 978-0-7110-3277-4. 
  2. ^ Class 171 - Welcome to the Southern E-Group Web Site. Retrieved 2011-05-01.
  3. ^ Southern On Train Facilities - Retrieved 2011-05-10.
  4. ^ Class 170 2Page - Welcome to the Southern E-Group Web Site. Retrieved 2011-05-01.
  5. ^ a b The Junction Class 171 Fleet List
  6. ^ Booth, Chris (December 2015). "The Turbostar Family". Today's Railways (Platform 5 Publishing) (168): 38.