British Rail Class 377
| Industry | Rail vehicle manufacturing |
|---|---|
| Headquarters | Derby , United Kingdom |
| Products | British Rail Class 377 Electrostar electric multiple units |
The British Rail Class 377 Electrostar represents a British dual-voltage electric multiple unit designed for passenger service, manufactured by Bombardier Transportation on the Electrostar platform at Derby Litchurch Lane Works between 2001 and 2014.
Description
These trains provide suburban transit across South London and serve main-line commuter routes extending to Sussex, Surrey, Kent, and the South Coast. They replaced slam-door stock such as the over four-decade-old 4Cig and 4Vep, which no longer met contemporary safety regulations. Introduced in the early 2000s, their deployment encountered obstacles: the fully air-conditioned models increased electricity demand, prompting substantial enhancements to the 750 V DC third-rail infrastructure in the former Southern region. The failure of Railtrack following the Hatfield incident further postponed these power supply improvements, delaying full operational status until 2003.
Class 377 units are equipped with external CCTV, designated spaces for wheelchairs, prams, and bicycles, as well as toilets located in intermediate cars. Their bodyside doors are electrically actuated, replacing older pneumatic door systems. Dual-voltage variants incorporate a Brecknell Willis high-speed pantograph featuring aerofoil stabilizers for overhead line contact.
The typical 5-car Class 377 formation includes:
- DMOC(A) – two motors on the inner bogie, sanding equipment, auxiliary power converter
- MOSL – two motors on the inner bogie, standard toilet (not present on 377/3 units)
- PTSOL – pantograph, transformer, compressor, universal-access toilet
- MOS – two motors on the inner bogie, standard-class interior (exclusive to Class 377/6 and 377/7)
- DMOS(B) – two motors on the inner bogie, sanding equipment, auxiliary power converter
In four-car sets, driving cars combine first-class saloons situated between the cab and front passenger doors; these formations omit the MOS coach.
Couplers
Class 377 trains are fitted with Dellner couplers instead of the Tightlock couplings originally installed on Class 375 units. After conversion, Southern's Class 375s were re-designated as Class 377/3s but maintained their original three-car arrangements. Similarly, Southeastern’s converted subclasses adopted Dellner couplers without undergoing reclassification. Additionally, subclasses 375/8 and 375/9 were constructed with Dellner couplers from inception.
Traction current supply
Each unit draws power from a 750 V DC third-rail system via eight pick-up shoes per train—twice the number found on earlier four-car EMUs—ensuring reliable operation over most third-rail discontinuities. Dual-voltage subclasses 377/2, 377/5, and 377/7 are equipped with pantographs to collect 25 kV AC from overhead lines. These models (along with single-voltage 377/6s) feature air-operated shoe mechanisms that retract when de-energized or when operating under overhead AC supply. This arrangement facilitates seamless transitions between third-rail DC and overhead AC power on routes such as Hemel Hempstead to Clapham Junction via the West London line. Since March 2009, dual-voltage Class 377s have operated certain Thameslink services between Bedford and Brighton as well as Rochester and Ashford; Bedford-Brighton services now use Class 700 trains while Class 377/5s continue serving Southeastern routes.
Trailer cars within each unit include roof recesses designed to accommodate future pantograph installations, enabling potential conversion for overhead AC operation.
Expansion of Fleet and Thameslink Programme
In April 2007, Southern revealed plans to acquire 48 extra Class 377 carriages aimed at substituting an equal number of Class 319 units that were reassigned to First Capital Connect (FCC). Later, an additional 11 dual-voltage units were incorporated, raising the total to 23. These trains were initially prepared at Southern’s Selhurst depot before being transferred to FCC’s Bedford Cauldwell facility. The inaugural unit, numbered 377501, was delivered in February 2009 and primarily operated on Bedford-Brighton services; during peak times, joint operations by FCC and Southeastern extended to Rochester and Ashford.
Due to delays in the delivery of Class 377/5 units, eight Southern Class 377/2 trains were temporarily allocated to FCC in March 2009. To compensate, Southern utilized cascaded Class 350/1 units from London Midland until September of that year.
Facing further postponements in Thameslink rolling stock arrivals which delayed the handover of Class 377/5s, Southern commenced an order for 130 vehicles in September 2011. Bombardier was awarded the contract in December 2011, which included options for eight dual-voltage five-car Class 377/7 units.
In December 2011, three Class 377/2 units were transferred from Southern to FCC to support the enhancement of 12-car Thameslink services.
By mid-2013, newly manufactured Class 377/6 trains from Derby began testing and entered passenger operations from October onwards on peak services such as those on the Sutton and Mole Valley routes.
As part of the Department for Transport’s Thameslink, Southern and Great Northern franchise agreements announced in September 2013, Southeastern procured a total of 25 Class 377 units—comprising 23 Class 377/5s and two Class 377/1s.
Refurbishment Programme
Porterbrook is committing £55 million over five years through Project Aurora to upgrade 214 Class 377 Electrostars operating on Southern routes. Refurbishment commenced in 2020 at Selhurst depot, with unit 377430 completed early in 2021. Enhancements encompass installation of live service information screens for GTR and London Underground lines, USB charging ports, power outlets, energy-saving LED lighting, and a passenger-counting system designed to improve service planning.
Southern
- Mainline and Redhill Routes: Services running between London Victoria and London Bridge to Brighton, Reigate, Tonbridge, Eastbourne, Ore, Portsmouth, Southampton, Littlehampton, Bognor Regis
- East Coastway: Routes from Brighton to Seaford, Eastbourne, Hastings, Ore
- West Coastway: Connections from Brighton to Portsmouth, Littlehampton, Bognor Regis, Southampton
- West London Route: Operating between Clapham Junction and Watford Junction
- Oxted Line: London Victoria to East Grinstead services
- Outer Suburban: Trains from London Victoria and London Bridge towards Tattenham Corner, Epsom, Horsham, Dorking
- Inner Suburban: Routes linking London Victoria and London Bridge with Caterham, Sutton, Epsom Downs, West Croydon, Beckenham Junction via Crystal Palace
Southeastern
In December 2016, Southeastern (Govia) took delivery of eight units (377501-377508) transferred from Thameslink, followed by an additional seventeen units (377509-523 & 377163/164) in September 2017. Furthermore, Southeastern is scheduled to receive thirteen Class 377/1 units (377121-133) from Southern as replacements for older Class 465 trains; units 377121 and 377122 commenced service in January 2025.
Great Northern
Back in 2016, there was an initial plan to allocate 19 out of the 23 Class 377/5 units to Great Northern for direct London-Cambridge services. However, this plan changed, and instead, 29 ex-Thameslink Class 387/1 units were reassigned. Subsequently, the Class 377/5 trains were redeployed to Southeastern to address their capacity requirements.
Fleet information
| Class | Operator | Number built | Year of manufacture | Cars per unit | Unit numbers | Remarks |
|---|---|---|---|---|---|---|
| 377/1 | Southern | 55 | 2002–03 | 4 | 377101-377120, 377125, 377131-377164 | All operate on third-rail lines. Units 377163 and 377164 were transferred from Southeastern to Southern in May 2022 following the retirement of Class 455. |
| Southeastern | 9 | 377121-377124, 377126-377127, 377129 | These units were moved from Southern. | |||
| 377/2 | Southern | 15 | 2003–04 | 377201-215 | Dual-voltage units deployed on South London Metro routes and occasionally on mainline services along the South Coast. | |
| 377/3 | 28 | 2001–02 | 3 | 377301-328 | Originally converted from Class 375 by substituting Tightlock couplers with Dellners; these three-car sets started on Coastway routes before moving to London suburban lines. Some returned to Coastway operations after Class 313 withdrawal. | |
| 377/4 | 75 | 2004–05 | 4 | 377401-475 | All operate on third-rail routes. Unit 377442 was reclassified back to /4 in July 2021 after several years as a /3. | |
| 377/5 | Southeastern | 23 | 2008–09 | 377501-523 | Dual-voltage units transferred from Thameslink between 2016 and 2017 to bolster Southeastern’s Class 375 fleet. | |
| 377/6 | Southern | 26 | 2012–13 | 5 | 377601-626 | Operate suburban London routes extending to Dorking, Horsham, Tattenham Corner, and Caterham, with weekend services to Brighton and special event runs on the East and West Coastway lines. |
| 377/7 | 8 | 2014 | 377701-708 | These dual-voltage five-car sets serve routes between East Croydon and Watford Junction/Hemel Hempstead alongside metro duties with the 377/6 fleet. Constructed at a cost of approximately £60 million, they entered service in December 2014. |
Incidents and accidents
On 28 November 2016, a fire broke out inside the MOSL carriage of Southern Class 377 unit number 377442 at Eastbourne station, damaging the interior. The fire was traced to defective wiring in a hand dryer located within the toilet.
On 17 February 2018, unit 377454 collided with a vehicle at a level crossing near Barns Green, Horsham, leading to two fatalities.
On 8 May 2019, unit 377142 impacted the buffer stops at London Victoria station.
On 23 August 2020, unit 377317 derailed while leaving Tonbridge Jubilee Sidings; maintenance teams worked promptly to re-rail the train and conduct inspections of signalling and track infrastructure.