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Class 377 Electrostar
Bombardier's Electrostar and Southern's main train: 203 units of three, four or five cars. Southeastern runs 36 more, second-hand: 23 dual-voltage 377/5s from Thameslink and, from December 2024, thirteen 377/1s (377121-133) from Southern.
Shown
Scale
265 ft (80.74 m) (the cars’ lengths added)
Class 377 Electrostar · schematic drawing GB Trains · gbtrains.uk/stock/377/ · CC BY 4.0
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Liveries 2
The same measured train in each livery, each drawn from a cited source. The drawing above shows the largest fleet’s.
Special liveries 1
- NHS thank-you wrap, 377111 April 2020.
- Type
- Electric multiple unit
- Builder
- Bombardier Transportation (now Alstom)
- Family
- Electrostar, with Class 357 Electrostar, Class 375 Electrostar, Class 376 Electrostar, Class 379 Electrostar, Class 387 Electrostar
- Built
- 2002–2014
- In service
- since 2003
- Operators
- Southern, Southeastern
- Formation
- 4 cars (377/1, /2, /4, /5): DMOS-MOSL-PTOSL-DMOS; 3 cars (377/3): DMOS-PTOSL-DMOS; 5 cars (377/6, /7): DMOS-MOSL-PTOSL-MOS-DMOS. Only the dual-voltage units' PTOSL carries a pantograph
- Trains in fleet
- 239: 64 377/1s (377101-164), 15 377/2s, 28 377/3s, 75 377/4s, 23 377/5s, 26 377/6s and 8 377/7s (377701-708)
- Fleets
- Southeastern: 36; Southern: 203
- Power
- 750 V DC third rail; the 377/2s, 377/5s and 377/7s also 25 kV AC overhead (dual voltage) · how it works
- Bogies
- Bombardier Electrostar bogies · drawn with the same bogie component as Class 357 Electrostar, Class 375 Electrostar, Class 376 Electrostar, Class 378 Capitalstar, Class 379 Electrostar, Class 387 Electrostar
- Train length
- 265 ft (80.74 m) (the cars’ lengths added)
- Coupled
- 3 × 4 cars, about 795 ft (242 m) (the units’ lengths added)
- Car height
- 12 ft 5 in (3.796 m)
- Profile
- main-line
- Status
- In service: 203 with Southern (in public ownership since 31 May 2026) and 36 with Southeastern; GTR's Project Aurora refresh of every sub-fleet finished in October 2025.
unverified Some of these figures haven’t yet been checked against an official source or a published history. What’s in doubt ↓
Car types
| Code | Car | Length | Doors per side |
|---|---|---|---|
| DMOS | Driving motor (DMOS) | 66 ft 11 in20.39 m | 2 double |
| MOSL | Motor with toilet (MOSL) | 65 ft 7 in19.98 m | 2 double |
| PTOSL | Pantograph trailer with toilet (PTOSL) | 65 ft 7 in19.98 m | 2 double |
Sources
How we source figures → · Spotted a mistake? Tell us → (opens in a new tab)
Show the 39 sources from Wikimedia Commons, RAIL magazine, Eversholt Rail and 7 more
- 377208 roof 5Y63 Blackfriars to Grove Park CSD - 16796057801.jpg (photograph: 377208's pantograph well from above; CC BY-SA 2.0) Wikimedia Commons (train_photos, via Flickr), 12 March 2015the pantograph's post insulators: ribbed, 4 sheds each (insulators in pantographs_mm; layout and proportion only, 377208's roof photographed close)
- Southeastern to receive 13 Class 377s from Govia Thameslink as part of EMU reshuffle Rail, 28 November 202413 Class 377/1s from Govia Thameslink
- Southeastern's fleet upgrade continues with the introduction of improved trains Southeastern, 28 November 2024transfer, maintenance by Govia Thameslink Railway; the 23 Class 377/5s already at Southeastern, which the 13 377/1s join
- Class 375 exterior livery sheets EVL-C1-2018859 G (DMOS), 2018861 F (MOSL), 2019035 A (MOSL 375/9), 2018860 E (PTOSL) Eversholt Rail (released by Southeastern under FOI: 'Livery Designs'), 2021the Class 375 layout and Southeastern colours the drawing uses; the yellow nosing and dark grey step under every doorway (2018859 G, 2018861 F; set T2, 13 October 2026)
- Class 377 'Electrostar' Southern Electric Group (sremg.org.uk), 2010377/3s built as 375s, converted by fitting Dellner couplers
- British Rail Class 377 Wikipediathe 377/3 conversion (cross-check)
- Class 377 Driver Manual (final disclosure extract, issue 1, October 2017) Govia Thameslink Railway (released under FOI2026-3260), September 2026, pp. 7-10power by subclass (p. 7: 377/1, /3, /4 and /6 DC only; 377/2, /5 and /7 AC and DC; the PTOSL the dual-voltage car); the MOS, on five-car units only (p. 8); the unit formations per subclass (pp. 9-10); every car end green in Southern's colours (pp. 7-10, side diagrams)
- Southeastern Class 377 photographs (377 515, 377 502) Wikimedia Commons (hugh llewelyn CC BY-SA 4.0; JOHN K THORNE CC0), 2024-2026photograph check of the layout; roof colour
- Govia Thameslink Railway begins cascade of Class 377s and 387s Rail, 13 February 2025203 Class 377s at GTR after the 2025 transfers, and 36 at Southeastern when the cascade is complete: 239 in all
- Class 377 'Electrostar' Southern Electric Group (sremg.org.uk), 2010the Southern subclasses as built: 64 377/1s (377101-164), 15 377/2s, 28 377/3s and 75 377/4s
- A new dawn for Electrostars as £100m project nears completion RAIL magazine, 2025-07-22The original Southern Class 377 fleet was built by Bombardier at Derby around the turn of the century and finally entered traffic in 2003 after a delayed introduction
- Govia Thameslink Railway's huge Project Aurora fleet upgrade comes to a close after five years RAIL magazine, 2025-10-16The 377s entered service in 2003
- Class 377 order Railway Gazette International, 2002-03-01Govia ordered 460 more Electrostar cars in March 2002, with the first unit due at Brighton on 14 March 2002 and service hoped for in summer 2002 (read through a search summary
- Southern starts running new five-car Class 377/7s RAIL magazine, 2014-07-23The last 377 batch, the 377/7s (377701–708), entered traffic from 23 June 2014, which puts the end of the build in 2014; 26 377/6s and eight 377/7s; Porterbrook owns Southern's 377s
- Adtranz P3-25 bogie (6647161053) (photograph of a Class 375/7's bogie at London Bridge, CC BY-SA 2.0) Wikimedia Commons (Hugh Llewelyn, via Flickr), June 2010the bogie drawing's layout (an Electrostar P3-25 bogie, photograph: layout only)
- Bogie and traction equipment beneath Door A1 of Class 375 Electrostar unit 375831 at Gillingham railway station (Kent) (photograph, CC0) Wikimedia Commons (OathOn), 25 June 2025the bogie drawing's layout (an Electrostar P3-25 bogie, photograph: layout only)
- British Rail Class 378 bogie and shoegear (photograph at Hackney Wick, CC BY-SA 3.0) Wikimedia Commons (Chris McKenna), 14 March 2014the bogie drawing's layout (an Electrostar P3-25 bogie, photograph: layout only)
- Farringdon station MMB 07 377521.jpg (mattbuck, CC BY-SA 3.0) Wikimedia Commons, 19 October 2010a 377/5's folded pantograph in its roof well, its knee and head ends (layout only)
- 377 side on (Southern Class 377 driving car) Wikimedia Commons (CC BY-SA 2.0), 29 February 2016the yellow at the cab front, side on (job yellow, 13 October 2026); square window corners (the first-class window and the first door's), and the DMOS's underframe: the equipment from under the first door, down to about 1 ft 5 in (430 mm; set T2, 13 October 2026)
- Govia Thameslink Railway's huge Project Aurora fleet upgrade comes to a close after five years RAIL magazine, 2025-10-16Project Aurora, the refresh of all seven 377 sub-fleets at Selhurst, finished in October 2025
- Britain's biggest train operator enters public ownership Infrastructure Intelligence (ACE), 1 June 2026GTR (Southern) in public ownership from 31 May 2026, run by DfT Operator Ltd
- Bodyside of 377 133.jpg (photograph, CC BY 4.0) Wikimedia Commons (Three76Five43Nine72), 3 May 2026377133, the last of 377121-133, in Southeastern service by 3 May 2026; the door step's yellow nosing
- 377511, London Charing Cross, August 23rd 2024.jpg (photograph, CC BY-SA 4.0) Wikimedia Commons (Southsea_Matt), 23 August 2024the burgundy universal-access panel on a 377/5's PTOSL (377511, August 2024; layout only)
- Class 375 Eversholt Railthe Class 375's car lengths (66 ft 11 in and 65 ft 7 in (20.39 and 19.98 m)), which the drawing and the page use; no speed, width or seats for the 377
- GWR Class 387.png (side diagram, 2017, CC BY-SA 4.0) Wikimedia Commons, 2017the windscreen's wrap pane and the yellow below it, seen side on (set ESW)
- Twyford - GTSR 387205 coupled to GWR 387146.JPG (photograph, 5 October 2021, CC BY-SA 4.0) Wikimedia Commons, 5 October 2021the windscreen's wrap pane and the yellow below it, seen side on (set ESW)
- 357 029 Shadwell.jpg (photograph, CC BY 4.0; uploaded June 2026) Wikimedia Commonsthe windscreen's wrap pane and the yellow below it, seen side on (set ESW)
- Southeastern Class 375 photographs: 375622 at Longfield (Matt Taylor, CC BY-SA 4.0, 2024), 375830 at St Johns (kitmasterbloke, CC BY 2.0, 2024), 375307 at Allington Quarry (John K Thorne, public domain, 2023), 375920 (Samson Ng, CC BY-SA 4.0, 2025), 375304 at East Farleigh (John K Thorne, public domain, 2021), Whitstable (ClemRutter, CC BY-SA 4.0, 2018) Wikimedia Commons, 2018-2025the windscreen's wrap pane and the yellow below it, seen side on (set ESW)
- Class 375 exterior livery sheets EVL-C1-2018859 G (DMOS), 2018861 F (MOSL), 2019035 A (MOSL 375/9), 2018860 E (PTOSL) Eversholt Rail (released by Southeastern under FOI: 'Livery Designs'), 2021the PTOSL's roof well, 1 ft 8 in to 12 ft 1 in (500-3,680 mm) from the No. 1 end (2018860 E; set TF, 20 October 2026)
- Reading - GWR 387150 coupled to GTSR 387206.JPG (photograph, CC BY-SA 4.0) Wikimedia Commons (Geof Sheppard), 4 October 2021the cab's Dellner coupler: where it stands and its heads' heights (set BC2, 20 October 2026; layout only)
- King's Lynn station Norfolk class 379 and 387 (379028 side on, from the DMCO's cab end; photograph) Wikimedia Commons (Norfolks disused railways, CC BY 4.0), 27 February 2025the cab's Dellner coupler: where it stands and its heads' heights (set BC2, 20 October 2026; layout only)
- 387129 working 1N25 Southampton Central to Brighton at Cosham 26 04 25 (54477933929) Wikimedia Commons (CC BY-SA 2.0)the cab's Dellner coupler: where it stands and its heads' heights (set BC2, 20 October 2026; layout only)
- 377 133 coupled to 377 522.jpg (photograph, CC BY 4.0) Wikimedia Commons (Three76Five43Nine72), 3 May 2026the cab's Dellner coupler: where it stands and its heads' heights (set BC2, 20 October 2026; layout only)
- 377 side on (Southern Class 377 driving car) Wikimedia Commons (CC BY-SA 2.0), 29 February 2016the saloon and door windows' heights, 6 ft 2 in to 9 ft 4 in (1,880-2,850 mm; set TFF, Kyle, 26 October 2026)
- Bodyside of 377 133.jpg (photograph, CC BY 4.0) Wikimedia Commons (Three76Five43Nine72), 3 May 2026the window heights' cross-check, about 6 ft 3 in to 9 ft 4 in (1,900-2,850 mm; at an angle; set TFF, Kyle, 26 October 2026)
- British Rail Class 377 377517 Gillingham Station, Kent.jpg (photograph, CC BY 4.0) Wikimedia Commons, 13 June 2024the cab-side window on the cab-left side (set TFF, Kyle, 26 October 2026)
- Southeastern Class 377 photographs (377 515, 377 502) Wikimedia Commons (hugh llewelyn CC BY-SA 4.0; JOHN K THORNE CC0), 2024-2026no cab-side window on the cab-right side (377515; set TFF, Kyle, 26 October 2026)
- Southern Class 377 377426.jpg (photograph, CC BY 2.0) Wikimedia Commons (andreboeni), 27 July 2021the green at the inner car ends, between cars 2-3 and 3-4 (oblique: layout only; set T2, 13 October 2026)
- British Rail Class 700 Wikipedia, read 13 October 2026the livery, its unit and its dates
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unverified
- Car lengths and height are the Class 375's (Eversholt's figures and livery sheets); no Class 377 dimensions, speed or seats found in a lessor's or operator's source
- The train's length is the cars' lengths added (Eversholt's Class 375 figures, 20.39 + 19.98 + 19.98 + 20.39 m), and Eversholt doesn't say whether they are over couplers or over the bodies
- Drawn as the Class 375 (no 377 drawing has been released): car lengths, doors and windows are the 375's, checked on one photograph to about 100 mm
- Roof colour from photographs (no paint reference); which end of the PTOSL the burgundy panel is at
- The window band: drawn 6 ft 4 in to 9 ft 4 in (1,931-2,833 mm; saloon) and 6 ft 4 in to 9 ft 4 in (1,935-2,835 mm; doors), from the Class 375's sheets; a side-on photograph of a Southern DMOS (commons-377-side-on, 2016) reads about 6 ft 2 in to 9 ft 4 in (1,890-2,850 mm), about 40 mm lower at the foot; held until a second photograph agrees
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