Editing Standard Corridor (section)

{{Short description|British mid-20th century railway carriage}}
{{no footnotes|date=July 2018}}
{{refimprove|date=July 2018}}
{{Use dmy dates|date=December 2017}}
{{Use British English|date=December 2017}}
{{Infobox train
| background       = #0033cc;color:white
| name             = British Rail Second Corridor
| image            = BR Mk1 SK.jpg
| imagesize        = 300px
| imagealt         = 
| caption          = A Mk1 Second Corridor (SK) coach at the North Norfolk Railway in 2007
| interiorimage    = 
| interiorimagealt = 
| interiorcaption  = 
| service          = 1951–present
| manufacturer     = BR Ashford/Easteigh, [[Derby Carriage and Wagon Works|Derby (C&W)]], Doncaster, [[Swindon Works|Swindon]], Wolverton, York, [[Birmingham Railway Carriage and Wagon Company|BRCW]], [[Cravens]], [[Gloucester Railway Carriage and Wagon Company|GRCW]], & [[Metro Cammell]]
| factory          = 
| family           = [[British Railways Mark 1]] and [[British Rail Mark 2|Mark 2A, 2B and 2C]]
| replaced         = 
| yearconstruction = ''Mk1'' 1951–1963<br>''XP64'' 1964<br>''Mk2a'' 1968<br>''Mk2b'' 1969<br>''Mk2c'' 1969-70
| yearservice      = 
| refurbishment    = 
| yearscrapped     = 
| numberbuilt      = 2168
| numberservice    = 
| numberpreserved  = 
| numberscrapped   = 
| fleetnumbers     = ''Mk1'' 24000–25507, 25510–26217<br>''XP64'' 25508-25509<br>''Mk2a'' 19452-19473<br>''Mk2b'' 19478-19513<br>''Mk2c'' 19515-19560
| capacity         = ''Mk1'' 48 with armrests<br>64 without<br>Mk2a/b/c 42
| operator         = [[British Rail]]
| depots           = 
| lines            =

| carbody          = 
| carlength        = {{convert|64|ft|6|in|m|2|abbr=on}}
| width            = {{convert|9|ft|3|in|m|2|abbr=on}}
| height           = {{convert|12|ft|9+1/2|in|m|2|abbr=on}}
| floorheight      = 
| platformheight   = 
| entrylevelorstep = 
| doors            = Manual slam doors, three on each side
| art-sections     = 
| maxspeed         = ''BR1:'' {{convert|90|mph|0|abbr=on}}<br>''B4/CW:'' {{convert|100|mph|0|abbr=on}}
| weight           = {{convert|32.5|to|36.5|LT|t ST|1}}
| aux              = 
| powersupply      = 
| hvac             = [[Steam generator (railroad)|Steam]] or [[Head end power#Electric Train Heat (ETH) and Electric Train Supply (ETS)|electric heat]], or both
| bogies           = BR1, Commonwealth or B4
| brakes           = [[Vacuum brake|Vacuum]], [[Railway air brake|air]], or [[Vacuum brake#Dual couplers|both]]
| coupling         = [[Railway coupling#Sets of carriages|Drop-head]] [[Janney coupler|knuckle coupler]] on [[Buffers and chain coupler|draw-hook]] ([[Railway coupling#Sets of carriages|dual]])
| gauge            = {{RailGauge|ussg|allk=on}}
}}

The '''Second Corridor''' (previously '''Third Corridor''') type of [[Passenger car (rail)|railway carriage]] was one of the standard mid-20th century designs, and was coded '''SK''' (previously '''TK''') by the LNER and BR, and '''CF''' by the LMS. The layout of the coach was a number of compartments, all of which were second class (known as third class until 1956), linked by a side [[Corridor (rail vehicle)|corridor]].

The [[British Railways Mark 1]] SK was the most numerous carriage design ever built in the United Kingdom. The original number series carried was 24000–26217. From 1983, those carriages in the 25xxx and 26xxx series were renumbered 18xxx and 19xxx.

There were two variants, those built for the Midland, Scottish, and Eastern / North Eastern regions had six seats per compartment, with fold-up arm-rests which folded into the seat-back, while those built for the Southern and Western regions, with their heavy commuter loadings into London, had eight seats in each compartment, and no arm-rests. Seating was of the interior sprung bench type.  Over time, some SKs and BSKs were re-allocated from other regions to the Western, who tended to try to stitch the arm-rests in the up position.{{clarify|date=July 2021|reason=Reads very anecdotally. Tended to try? Can we have some cited facts please?}}

In 1985, a number of [[British Rail Mark 2|Mark 2]] [[First Corridor]] carriages were declassified to become SKs. They were renumbered from 13xxx to 19xxx, putting them after the end of the Mark 1 range (19452–19560).

No carriages of this type are still in daily use on the main line network, since open saloon carriages are now preferred by operating companies. However, some electric [[multiple unit]]s based on [[British Rail Mark 1|Mark 1]] coaches have standard class compartments, such as {{brc|438}}. Many SKs still operate on preserved UK railway lines.

Designations for second corridor carriages are as follows:

{|class="wikitable"
!LNER Code
!Description
!LMS Code
|-
|BSK
|Brake Second Corridor
|CH
|-
|DMBSK
|Driving Motor Brake Second Corridor
|-
|DMSK
|Driving Motor Second Corridor
|-
|MBSK
|Motor Brake Second Corridor
|-
|SK
|Second Corridor
|CF
|-
|TBSK
|Trailer Brake Second Corridor
|-
|TSK
|Trailer Second Corridor
|}