Built: 2015 – 2019
Manufacturer: Bombardier Transportation, Derby
Entered Service: 2019
Number in Service: 
30 x 4 car 25Kv AC units
18 x 4 car 25Kv AC/750v DC units
6 x 5 car 25Kv AC/750v DC units
Number of Carriages per Train: 4/5
Seats per Train: 189/241
Passenger Capacity: 678/855 (approx.)

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Train Formation:  

4 Car: Driving Motor Standard – Pantograph Motor Standard – Motor Standard – Driving Motor Standard
5 Car: Driving Motor Standard – Motor Standard – Pantograph Motor Standard – Motor Standard – Driving Motor Standard

Train Length: 4 car: 271ft 11in 5 Car: 337ft 6in
Train Width: 9ft 2ins
Train Height: 12ft 5ins
Train Weight: 4 Car AC: 144 Tonnes, 4 Car DV: 151 Tones, 5 Car DV: 182 tonnes

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Sub Classes

Class 710/1 – 25Kv AC – Operated on Lea Valley Lines & Romford to Upminster Line.
Class 710/2 – 25KV AC/750v DC – Operated on Gospel Oak to Barking and Watford DC Lines.
Class 710/3 – 25KV AC/750v DC – 5 Car Sets Operated on Watford DC Line.

Class 710 Electric Multiple Unit History

At the beginning of 2012, following two years in service, Transport for London realised that the Class 172 Diesel Multiple Units it had procured for service on London Overground‘s Gospel Oak to Barking Line were unable to handle the passenger demand placed on the line.

TfL issued a tender for the supply of eight three or four-car diesel trains, however this was shelved as the Government announced the electrification of the Gospel Oak to Barking Line in June 2013 and the proposal to operate the line with a fleet of electric multiple units.

With this new proposal, TfL saw an opportunity to modernise the remaining original members of its fleet, and therefore expressions of interest were invited for a total of 39 four-car electric multiple units, 30 for the Lea Valley Lines, 1 for the Romford to Upminster Line (to replace the Class 315/317 EMUS still in service) and 9 for the Gospel Oak to Barking services, replacing the Class 172 DMUs.

Subsequently, 6 five-car units were added to the tender to allow the five-car Class 378 Capitalstar EMUs on the Watford DC Lines to be returned to the North/East London Lines.

An invitation to Tender was issued by Transport for London in early 2015. July of that year saw an announcement from TfL that they had placed a £260million order with Bombardier Transportation for 45 four-car Class 710 Aventra Electric Multiple Units, with an option for a further 24 units and additional options for the supply of extra carriages to extend some units to five cars.

Beginning in April 2018, the delivery schedule for the new units began to slip, with further delays being announced in June of that year. Transport for London reported in November that they hoped the units would commence service in December however further delays, including in unit testing, prevented this.

Due to the lease on the existing Gospel Oak to Barking units becoming due in January 2019, and the need to transfer them to other lines, TfL temporarily deployed three Class 378 Capitalstar units to cover services on the line until the Class 710s became available.

In early May 2019, the Class 710 EMUs gained approval to enter passenger service from the Office of Rail and Road, with the first two units entering service on the Gospel Oak to Barking Line on 23 May, with the remaining six entering service in August.

The first unit for the Watford DC Lines entered service on the 9th September 2019 with the rest commencing service over the following months. Units on the Lea Valley Lines began running on the 3rd March 2020 and the Romford to Upminster Line on 5th October.

Built: 2008 – 2015
Manufacturer: Bombardier Transportation, Derby
Entered Service: 2009
Number in Service:  57
Number of Carriages per Train: 5
Seats per Train: 186
Passenger Capacity: 840 (approx.)

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Train Formation:  Driving Motor Open Saloon – Motor Open Saloon – Pantograph Trailer Open Saloon – Motor Open Saloon – Driving Motor Open Saloon

Train Length: 324ft 7in
Train Width: 9ft 2ins
Train Height: 12ft 4ins
Train Weight: 212.8 tonnes

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Sub Classes

Class 378/1 – 750v DC – Operated on East London Line only.
Class 378/2 – 25KV AC/750v DC – Operated on North London Line, West London Line & East London Line

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Class 378 Electric Multiple Unit History

With the acquisition of the former Silverlink Metro services by Transport for London, followed by the formation of London Overground in 2007, the need for a fleet of replacement trains became quickly apparent. TfL turned to Bombardier Transportation, who produced a design based on their successful Electrostar family of electric multiple units.

The Class 378 Capitalstar, although similar in design to the Class 376 trains operated by Southeastern, features full longitudinal seating similar to that used on London Underground rolling stock, which provides more standing capacity within each train and helps to reduce overcrowding.

The original deal was for 152 individual carriages to be constructed, with a total cost of £223 million, although this order was extended by a further 36 carriages in July 2007. The first two complete 3-car trains were delivered to Willesden TMD in September 2008 and underwent a 14-week test period on the North London Line.

Class 378s were originally planned to enter service in January 2009 however, delays of 6 months due to the economic recession and its effects on suppliers of parts saw the first Class 378 unit eventually enter service on 29 July 2009.

Late 2010/early 2011 saw the trains extended with the addition of a 4th carriage. A further extension to 5 carriages began in November 2014, with all trains extended by December 2015.

In July 2015, London Overground announced an order for 45 new Bombardier Transportation Class 710 ‘Aventra’ units, some of which would displace the Class 378/2 units in use on the Watford DC line and allow their cascading to strengthen services on the other Class 378 operated lines.

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Built: 2010
Manufacturer: Bombardier Transportation, Derby
Entered Service: July 2010
Withdrawn From Service: March 2019
Number in Service:  8
Number of Carriages per Train: 2
Seats per Train: 124
Passenger Capacity: 350 (approx.)

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Train Length: 154ft 11in
Train Width: 8 ft 9ins
Train Height: 12ft 4ins
Train Weight: 83.2 tonnes

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Class 172 Diesel Multiple Unit History

Upon taking control of the former Silverlink Metro services in November 2007, Transport for London inherited a small fleet of Class 150 diesel multiple units to operate services on the Gospel Oak to Barking line.

One of the first realisations of the company was that, due to the mechanical unreliability of the incumbent units, new rolling stock would need to be obtained. As part of the procurement process, TfL approached Bombardier Transportation regarding their ‘Turbostar’ product, already in use with several UK operators.

The unit chosen was a lighter-weight variant of the popular Class 170, featuring longitudinal seating and hydraulic gears. The eight two-car units were purchased by Angel Trains, who leased them to London Overground and they started to enter service in July 2010, with full assumption of service in December of that year.

The overwhelming success of the London Overground services within their first 2 years led to the 2-car units becoming insufficient in capacity terms, with trains regularly filled beyond capacity. London Overground began a process to either add a third carriage to the trains or replace them completely with brand new 3 or 4-car DMUs.

The replacement process was turned on its head in June 2013, when the UK Government announced that the Gospel Oak to Barking line was to be electrified as part of a wider strategy. this led to a £260m order for 45 four-car Bombardier Class 710 Aventra Electric Multiple Units to replace the incumbent units on the Gospel Oak to Barking, Lea Valley Line and Watford DC Lines services.

The Class 172 units were due to begin being cascaded to West Midlands Trains in November 2018, with the introduction of the new Class 710s. However, the transfer did not occur as planned and the Class 172s did not leave the line until March 2019, being temporarily replaced by shortened Class 378 EMUs redeployed from other London Overground Lines.

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