British Rail Class 377

British Rail Class 377 Electrostar
Southern 377207 at Hemel Hempstead with a service from Milton Keynes Central to East Croydon
The interior of Standard Class in a DMOC vehicle in Classes 377/4 and 377/5
In service	May 2003 - Current
Manufacturer	Bombardier Transportation, Derby
Family name	Electrostar
Replaced	Class 319 (Thameslink) Class 456 (Metro) Class 421 (Mainline) Class 423 (Mainline)
Number built	211 units (excluding 28 375/3 conversions)
Number in service	239 units
Formation	377/1/2/4/5: 4 cars per unit (DMOC-MOC-PTOS-DMOC) 377/3: 3 cars per unit (DMOC-PTOS-DMOS) 377/6/7: 5 cars per unit (DMOC-MOS-PTOS-MOS-DMOS)
Operators	GTR Southern GTR Thameslink Future: Southeastern (2018)
Specifications
Car length	20.4 m (66 ft 11+1⁄8 in)
Width	2.80 m (9 ft 2+1⁄4 in)
Height	3.78 m (12 ft 4+7⁄8 in)
Maximum speed	100 mph (161 km/h)
Weight	173.6 t (170.9 long tons; 191.4 short tons) (377/1, /2, /4, /5) 133.1 t (131.0 long tons; 146.7 short tons) (377/3 only)
Power output	1.2 megawatts (1,600 horsepower) (377/1, /2, /4, /5) 0.8 megawatts (1,100 horsepower) (377/3 only)
Electric system(s)	750 V DC 3rd rail 25 kV 50 Hz AC Overhead lines (377/2, 377/5 and 377/7 only)
Current collector(s)	Contact shoe Pantograph (377/2, 377/5 and 377/7 only)
Multiple working	within class
Track gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge

The Class 377 Electrostar is a British electric multiple-unit train (EMU) built by Bombardier Transportation at its Derby Works, from 2001 to the present. The Electrostar family is the most numerous type of EMU built in the post-privatisation period of Britain's railways.

The class forms the major part of the Govia Thameslink Railway (GTR) fleet for Southern and Thameslink services. They are primarily seen on services in the south of England.

Description

The units work suburban services in South London, and main line commuter services to Sussex, Surrey, Kent and the South Coast, on which they replaced 4Cig and 4Vep slam-door stock which came to end of their useful lives and which did not meet modern health and safety requirements. Built in the early 2000s, the units had a troubled introduction; being fully air-conditioned, their higher power consumption compared to the slam-door Mark 1-based stock that they replaced led to major upgrades being required to the 750 V DC third-rail power supply used in the former Southern region. The collapse of Railtrack following the Hatfield accident further delayed this upgrade work, and the new stock did not enter squadron service until 2003.

Class 377s are fitted with external CCTV. There is a disabled seating area, and both intermediate coaches have toilets. Bodyside power doors are electrically operated, a move away from the air powered systems of previous generation EMUs. Dual-voltage units are fitted with a Brecknell Willis high-speed pantograph, incorporating a pair of aerofoils on the pan knuckle to steady the pan head against the OLE contact wire. The configuration of a 5-car Class 377 unit is:

• DMOC(A) - 2 motors on inner bogie, sander, auxiliary converter module
• MOSL - 2 motors on inner bogie, standard toilet
• PTSOL - pantograph, transformer, compressor, disabled toilet
• MOS - 2 motors on inner bogie, standard class interior (only found on Class 377/6 and 377/7 units)
• DMOS(B) - 2 motors on inner bogie, sander, auxiliary converter module

In 4-car units the driving cars are composite, with the first-class saloon between the driving cab and the first set of passenger doors. 4-car units also do not contain the MOS coach.

Couplers

The Class 377 uses Dellner couplers instead of the Tightlock type originally used on Southern's Class 375s. Southern's 375s were all converted to Class 377/3s - these reclassified units can still be identified by their 3-car formation. Note that Southeastern's 375s (sub-classes 375/3, 375/6, and 375/7) were also converted to Dellner couplers, but not reclassified; its 375/8 and 375/9 units were fitted with Dellner couplers as built.

Traction current supply

All units can receive power via third-rail pick-up which provides 750 V DC. There are eight pick-up shoes per unit (twice the number of previous generation 4-car Electric multiple units), and this enables them to ride smoothly over most third-rail gaps. The units in the 377/2, 377/5 and 377/7 sub-classes are dual-voltage, and are fitted with a pantograph to pick up 25 kV AC from overhead lines. On these units the shoe mechanism is air-operated so that when powered down, or working on AC overhead lines, they are raised out of the way. This is used on trains from Milton Keynes to East Croydon which use part of the West Coast Main Line between Milton Keynes and Willesden Junction, and then the West London Line towards Clapham Junction. These trains change to third-rail DC supply on a dual-voltage section of the West London line north of Shepherd's Bush. Since March 2009, dual-voltage Class 377 sets have also been operating some Thameslink Bedford to Brighton, Rochester and Ashford services. (See below).

Among the remaining units, the trailer coach in each unit has a recess in its roof where a pantograph could be fitted, to allow for future conversion to overhead AC power. Despite most units being DC-only, the class is numbered in the 3xx series normally used for AC units.

Additional units and the Thameslink Programme

In April 2007, as part of the Route Utilisation Strategy for the Brighton Main Line, it was announced that Southern would procure an additional 48 Class 377 carriages to replace an identical number of Class 319 carriages (12 4-car units) due to be transferred to First Capital Connect. Eleven further dual-voltage units were then added to the order, making a total of 23. They were ordered from Bombardier in March 2008 and were delivered in First's corporate colour scheme but with Southern spec interior (green seats). The units were commissioned at Southern's Selhurst depot in Croydon before being transferred to First Capital Connect's Bedford Cauldwell depot. The first of these, unit 377501, was delivered to Cauldwell depot on 27 February 2009 after making its first appearance through the Thameslink Central London core. The 377/5s operate mainly on Bedford to Brighton services but in the peaks form part of FCC's and Southeastern's new joint service to places such as Rochester and Ashford. Once FCC's new passenger vehicles come into service, the 377/5 fleet will be returned to Southern.

Delays in the construction of the Class 377/5s for First Capital Connect saw the temporary transfer of eight of Southern's Class 377/2s to FCC to enable them to implement the planned timetable changes on 22 March 2009; the loss of these units until September 2009 was covered by the temporary cascade of a number of Class 350/1s to Southern from London Midland, which operated services between East Croydon and Milton Keynes.

In September 2011 it was announced that Southern had begun the procurement of 130 vehicles, due to delays in the procurement of new Thameslink rolling stock that would prevent transfer of the 377/5s in time for the December 2013 timetable change. The contract was awarded to Bombardier in December 2011. The additional eight five-car units (from an option in the contract for 40 additional vehicles) are dual-voltage and known as Class 377/7.

In December 2011 three Class 377/2 units were transferred from Southern to First Capital Connect (now Thameslink) to allow more 12-car services to be run.

During mid-2013 the first of the new class 377/6s arrived from Derby for type testing, and since October 2013 these units have been used in passenger service, initially on a peak-hours London Bridge-West Croydon diagram. The /6 subclass has clear external differences from the previous subclasses, notably windows set in frames instead of the more expensive ribbon glazing of earlier units.

Southern liveried 377122 departing Warnham, with a service bound for Horsham

Southern liveried 377213 at Watford Junction, with a service bound for Brighton

Southern liveried 377448 at Tinsley Green

Thameslink 377508 arriving at St. Albans, with a southbound service for Brighton

Southern-liveried 377604 about to depart at London Victoria platform 9 with a Sutton service

Southeastern are expected to receive 25 Class 377 units in coming years according to Department for Transport documents published in September 2013, relating to the new combined Thameslink, Southern and Great Northern Franchise.

Current operations

Southern

• Mainline and Redhill Routes: London to Brighton, Horsham, Reigate, Tonbridge, Eastbourne, Ore, Portsmouth, Southampton, Littlehampton, Bognor Regis
• East Coastway: Brighton to Eastbourne, Hastings and Ore
• West Coastway: Brighton to Portsmouth, Littlehampton, Bognor Regis and Southampton
• West London Line: East Croydon to Milton Keynes Central
• Oxted Line: London to East Grinstead
• Outer Suburban services: Central London to Tattenham Corner, Horsham, Dorking, Guildford (selected workings)
• Inner Suburban services: Central London to Caterham, Sutton, Epsom, Epsom Downs, West Croydon, Beckenham Junction via Crystal Palace (selected workings)

Thameslink

• Thameslink: (Brighton-Gatwick Airport-London-Luton-Bedford also Bedford to Ashford/Rochester in peak hours)

Future Operations

Southeastern

Southeastern are expected to receive 25 Class 377/1 Southern units in 2017 according to Department for Transport documents published in September 2013, relating to the new combined Thameslink, Southern and Great Northern Franchise.

Aborted Proposals

Great Northern

Beginning 2016, 19 of the 23 Class 377/5 units were planned to be transferred for use on non-stop London-Cambridge services, however it has since been decided that the 29 Class 387/1s currently operating on Thameslink will be used instead.

Fleet details

Class	Operator	No. Built	Year Built	Cars per Unit	Unit nos.	Notes
Class 377/1	Southern	64	2002–2003	4	377101-164	All 3rd rail routes.
Class 377/2	Southern	6	2003–2004	4	377201-206	Dual-voltage units. These are used on the East Croydon - Milton Keynes Central route as well as Metro routes in South London and occasionally main line workings to the South Coast. 377207-377215 are on loan to Thameslink until the new Thameslink stock arrives.
	Thameslink	9			377207-215
Class 377/3	Southern	29	2001–2002	3	377301-328 377342	3-car units converted from Class 375 Nos. 375311-338 by having their Tightlock couplers replaced by Dellners. Originally used on Coastway services but have now moved to London suburban services, being replaced by Class 313s. 377342 was shortened after a fire at Eastbourne caused a coach to be written off.
Class 377/4	Southern	74	2004–2005	4	377401-441 377443-475	All 3rd rail routes. Units 377472 and 377474 had 'speed run' branding in reference to these units having formed the record breaking London to Brighton run. This branding was removed upon overhaul in late 2014.
Class 377/5	Southeastern	8	2008–2009	4	377501-508	23 dual-voltage units ordered by Southern. Transferred to Thameslink as part of the Thameslink Programme Key Output Zero (KO0). 8 transferred to Southeastern in December 2016.
	Thameslink	15			377509-523
Class 377/6	Southern	26	2012-2013	5	377601-626	All 3rd rail routes. Ordered as replacement for the three 377/2 and twenty-three 377/5 units on loan from Southern to Thameslink. The trains on loan to Thameslink won't be returned in time for lengthening services via Balham from 8 to 10 carriages. The Class 456 fleet was subsequently transferred to South West Trains. All trains have now entered service on the metro routes with some workings on the Brighton Main Line.
Class 377/7	Southern	8	2014	5	377701-708	Additional 8 dual-voltage units. 377701-377708 have entered service on metro services and on the East Croydon - Milton Keynes Central services. The option for 40 new vehicles from Bombardier appears in the manufacture and supply agreement for the order of 130 Electrostar vehicles from Bombardier announced by Southern on 28 December 2011. The MSA provides that the option for the further 40 vehicles expires on 31 December 2012. The 40 vehicles were built in 5-car formation with dual voltage configuration, costing circa £60 million in total, and they were delivered during 2014 for service entry in December of that year.

Diagrams

London-Brighton Speed Record

On 11 September 2005, units 377472 and 377474 set the record for a London Bridge to Brighton run of 36 minutes 56 seconds.