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British Rail Class 717

British Rail Class 717
Desiro City
Great Northern Class 717 unit at Palmers Green
The standard-class interior of a Class 717 unit
In service28 September 2018 – present
ManufacturerSiemens Mobility
Built atKrefeld, Germany
Family nameDesiro City
ReplacedClass 313
Constructed2018
Number built25
Formation
  • 6 cars per unit:
  • DMOS-TOS-TOS(L)W-MOS-PTOS-DMOS
Fleet numbers717001–717025
Capacity362 seats
OwnersRock Rail
OperatorsGreat Northern
DepotsHornsey (London)
Lines served
Specifications
Car body constructionAluminium
Train length121.7Β m (399Β ft 3Β in)
Car length20.2Β m (66Β ft)
Width2.80Β m (9Β ft 2Β in)
Floor height1.10Β m (3Β ft 7Β in)
DoorsDouble-leaf pocket sliding, each 1,500Β mm (59Β in) wide (2 per side per car)
Wheel diameter820–760Β mm (32.28–29.92Β in) (new–worn)
Wheelbase
  • Motor bogies: 2,200Β mm (87Β in)
  • Trailer bogies: 2,100Β mm (83Β in)
Maximum speed85Β mph (137Β km/h)
Weight204Β t (201Β LT; 225Β ST)
Axle load
  • Motor bogies: 15.5Β t (15.3Β LT; 17.1Β ST)
  • Trailer bogies: 14.5Β t (14.3Β LT; 16.0Β ST)
Traction systemSiemens IGBT
Power output1,200Β kW (1,600Β hp) at wheels
Acceleration0.85Β m/s (1.9Β mph/s)
Electric system(s)
Current collector(s)
UIC classification
  • Boβ€²Boβ€²+2β€²2β€²+2β€²2β€²+Boβ€²Boβ€²+2β€²2β€²+Boβ€²Boβ€²
BogiesSiemens SGP SF7000
Minimum turning radius120Β m (390Β ft)
Braking system(s)Electro-pneumatic (disc) and regenerative
Safety system(s)
Coupling systemDellner
Track gauge1,435Β mm (4Β ftΒ 8+1⁄2Β in) standard gauge


The British Rail Class 717 Desiro City is an electric multiple unit passenger train built by Siemens Mobility, currently operated by Govia Thameslink Railway on its Great Northern Hertford Loop and Welwyn stopping routes. Built to replace Class 313 trains on services into Moorgate, a total of 25 six-car units began entering regular service from March 2019. The units are similar to the Class 700s (in use with Thameslink) and the Class 707s (in use with Southeastern).

History


Upon winning the Thameslink, Southern and Great Northern franchise, Govia Thameslink Railway (GTR) announced that it would seek to procure new trains totalling 150 vehicles to replace the then-40-year-old Class 313 units operating on services to and from Moorgate. In December 2015, GTR announced that it had selected Siemens to provide this new fleet, originally designated Class 713, as a follow-on order from the main Class 700 order, with entry into service expected from March 2019. The order was finalised in February 2016.

A significant difference between Class 717s and the earlier Class 700s is the provision of fold-down emergency doors at both ends of each train. These are required for emergency evacuation of passengers while inside the deep-level Moorgate tunnels.

Siemens began testing the Class 717 units in Germany during June 2018.

Operation

The first unit operated a single preview service in late September 2018, with gradual introduction from the spring of 2019. The final Class 313 service on Great Northern ran in September 2019, completing the fleet replacement by Class 717 units.

In-cab signalling


In September 2021, the installation of European Train Control System (ETCS) on the Class 717 fleet was successfully tested on the Thameslink 'core' route between St Pancras International and Blackfriars stations in central London. The success of the test allowed Govia Thameslink Railway to work towards enabling the use of ETCS in passenger service on the Northern City Line in November 2023, which will be followed by the decommissioning and removal of the existing conventional signalling system in 2024. Further testing and implementation on other lines and routes is planned.

In October 2022, testing started for the upgrade of the ETCS baseline from B3MR1 to B3R2, with dynamic testing planned for December 2023.

Environment


Class 717 trains generate electricity through regenerative braking. The trains are also 20% lighter than their predecessors, making them more energy efficient.

Fleet details


Class Operator Qty. Year built Cars per unit Unit nos.
717 Great Northern 25 2018 6 717001–717025

Illustration

Side-profile illustration of a Great Northern Class 717 unit


Last updated 24 June 2025. All information and images sourced from the relevant Wikipedia article(s) unless stated otherwise. If any information is incorrect, please let us know by emailing us: [email protected]. Text is available under the Creative Commons Attribution-ShareAlike License 4.0; additional terms apply.