British Rail Class 717

The British Rail Class 717 Desiro City^[9] 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.^[10][11] The units are similar to the Class 700s (in use with Thameslink) and the Class 707s (in use with Southeastern).

British Rail Class 717 Desiro City
Great Northern Class 717 unit at Palmers Green
The standard-class interior of a Class 717 unit
In service	28 September 2018 – present
Manufacturer	Siemens Mobility
Built at	Krefeld, Germany
Family name	Desiro City
Replaced	Class 313
Constructed	2018
Number built	25
Formation	6 cars per unit: DMOS-TOS-TOS(L)W-MOS-PTOS-DMOS
Fleet numbers	717001–717025
Capacity	362 seats
Owners	Rock Rail[1]
Operators	Great Northern
Depots	Hornsey (London)
Lines served	East Coast Main Line Hertford Loop Line Northern City Line
Specifications
Car body construction	Aluminium[2]
Train length	121.7 m (399 ft 3 in)
Car length	20.2 m (66 ft)
Width	2.80 m (9 ft 2 in)
Floor height	1.10 m (3 ft 7 in)
Doors	Double-leaf pocket sliding, each 1,500 mm (59 in) wide (2 per side per car)
Wheel diameter	820–760 mm (32.28–29.92 in) (new–worn)[3]
Wheelbase	Motor bogies: 2,200 mm (87 in) Trailer bogies: 2,100 mm (83 in)[3]
Maximum speed	85 mph (137 km/h)
Weight	204 t (201 LT; 225 ST)
Axle load	Motor bogies: 15.5 t (15.3 LT; 17.1 ST) Trailer bogies: 14.5 t (14.3 LT; 16.0 ST)[3]
Traction system	Siemens IGBT
Power output	1,200 kW (1,600 hp) at wheels
Acceleration	0.85 m/s2 (1.9 mph/s)
Electric system(s)	25 kV 50 Hz AC overhead 750 V DC third rail
Current collector(s)	Pantograph (AC) Contact shoe (DC)
UIC classification	Bo′Bo′+2′2′+2′2′+Bo′Bo′+2′2′+Bo′Bo′
Bogies	Siemens SGP SF7000[4]
Minimum turning radius	120 m (390 ft)[3]
Braking system(s)	Electro-pneumatic (disc) and regenerative
Safety system(s)	AWS ETCS[5] TPWS Tripcock[6][note 1]
Coupling system	Dellner
Track gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge
Notes/references
Sourced from [8] unless otherwise noted.

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.^[12] In December 2015, GTR announced that it had selected Siemens to provide this new fleet, originally designated Class 713,^[4] as a follow-on order from the main Class 700 order, with entry into service expected from March 2019.^[13] The order was finalised in February 2016.^[14][15]

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^[9] while inside the deep-level Moorgate tunnels.^[16]

Siemens began testing the Class 717 units in Germany during June 2018.^[17]

Operation

The first unit operated a single preview service in late September 2018, with gradual introduction from the spring of 2019.^[18] The final Class 313 service on Great Northern ran in September 2019, completing the fleet replacement by Class 717 units.^[19]

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.^[20] 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.^[21] Further testing and implementation on other lines and routes is planned.^[22]

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.^[23] The trains are also 20% lighter than their predecessors, making them more energy efficient.^[24]

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

Notes

1. Tripcocks were removed in May 2023 following the May 2022 completion of the Northern City Line tripcock-to-TPWS conversion programme.^[7]