Editing Brighton Main Line (section)

===Windmill Bridge Junction to Balcombe Tunnel Junction===
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| annotations =      {{Annotation |90|195|← Windmill Bridge Jnc&nbsp;| text-align=left | font-size-css=85% | font-weight=bold | background-color=#C4C4C4 | color=black |line-height=1}}
| caption = The north Croydon area showing: {{rws|Selhurst}} station (red circle) on the line to {{rws|London Victoria}} (top left); the line to {{rws|London Bridge}} (top right); the line to {{rws|West Croydon}} (bottom left); the line to {{rws|Brighton}} via {{rws|East Croydon}} (bottom centre).
}}The Brighton Main Line between Windmill Bridge Junction and Balcombe Tunnel Junction is {{cvt|21|mi|26|ch}} long and has twelve stations in total.{{sfn|"Sectional Appendix"|2009|loc=SO500}} Gatwick Airport station is managed by Gatwick Express,<ref>{{cite web |title= Gatwick Airport |publisher= National Rail |url= https://www.nationalrail.co.uk/stations/gatwick-airport/ |access-date= 29 March 2024 }}</ref> but the other stations are managed by Southern. Gatwick Airport has seven operational platforms, East Croydon and {{rws|Purley}} have six, {{rws|South Croydon}} and {{rws|Three Bridges}} have five, {{rws|Purley Oaks}}, {{rws|Redhill}} and {{rws|Horley}} have four, and the remaining stations ({{rws|Coulsdon South}}, {{rws|Merstham}}, [[Earlswood railway station (Surrey)|Earlswood]] and {{rws|Salfords}}) have two platforms each.{{sfn|"Sectional Appendix"|2009|loc=SO500}}{{sfn|"Route Specifications"|2016|pp=69-72}} Train services that use this section of the Brighton Main Line are:
* Thameslink services to destinations in Sussex (including Brighton, Horsham and East Grinstead)
* Outer suburban services from London Bridge to Caterham and Tattenham Corner, operated by Southern
* Victoria to East Grinstead, Reigate and the South Coast, operated by Southern
* London Bridge to Uckfield, operated by Southern
* Hemel Hempstead to East Croydon via Kensington (Olympia), operated by Southern
* Victoria to Gatwick Airport and Brighton, operated by Gatwick Express
* {{rws|Reading}} to Gatwick Airport via {{rws|Guildford}}, operated by [[Great Western Railway (train operating company)|Great Western Railway]]

Between Windmill Bridge Junction and {{rws|South Croydon}} there are five parallel tracks, but for the remainder of this section there are four parallel tracks. Between Stoats Nest Junction and the south of Redhill station, the fast and slow lines diverge. The fast tracks are generally known as the Quarry Line, which provides a bypass route to avoid the junctions at Redhill. There are changes in track mileage on both the fast and slow lines to the south of Redhill. The maximum speed on this section of the Brighton Main Line is {{cvt|90|mph}}.{{sfn|"Sectional Appendix"|2009|loc=SO500}}

[[File:Merstham_orig_tunnel_south_portal.jpg|thumb|right|South portal of Merstham Tunnel]]
The Brighton Main Line passes in tunnel beneath the [[North Downs]]. The slow lines run through the {{cvt|1|mi|71|yd|adj=on}} [[Merstham tunnels|Merstham Tunnel]] and the fast lines pass through the longer, {{cvt|1|mi|353|yd|adj=on}} Quarry Tunnel. There is one additional tunnel on the Quarry Line, [[Redhill Tunnel]], which is {{cvt|649|yd}} long.{{sfn|"Sectional Appendix"|2009|loc=SO500}}

{|class="wikitable sortable collapsible collapsed"
|+ class="nowrap"|Stations from Windmill Bridge Junction to Balcombe Tunnel Junction {{nobold|(ordered from north to south)}}
|-
!scope="col"|Station
!scope="col"|Distance from London Victoria{{sfn|"Sectional Appendix"|2009|loc=SO500}}
!scope="col"|Number of<br> platforms
!scope="col"|Opening date 
!scope="col" class="unsortable"|Original name
!scope="col" class="unsortable"|Ref.
|- style="background:#F8F8FF"
|{{rws|East Croydon}}||{{cvt|10|mi|28|ch}}||6||{{date table sorting|12 July 1841}}||Croydon||{{sfn|Quick|2023|p=176}}
|-
|{{rws|South Croydon}}||{{cvt|11|mi|21|ch}}||5||{{date table sorting|1 September 1865}}||||{{sfn|Quick|2023|p=421}}
|-
|{{rws|Purley Oaks}}||{{cvt|12|mi|34|ch}}||4||{{date table sorting|5 November 1899}}||||{{sfn|Quick|2023|p=380}}
|-
|{{rws|Purley}}||{{cvt|13|mi|29|ch}}||6 (4 for main line)||{{date table sorting|12 July 1841}}||Godstone Road||{{sfn|Quick|2023|p=380}}
|-
|{{rws|Coulsdon South}}||{{cvt|17|mi|03|ch}}||2||{{date table sorting|1 October 1889}}||Coulsdon||{{sfn|Quick|2023|p=145}}
|-
|{{rws|Merstham}}||{{cvt|20|mi|59|ch}}||2||{{date table sorting|12 July 1841}}|| ||{{sfn|Quick|2023|p=313}}
|-
|{{rws|Redhill}}||{{cvt|22|mi|40|ch}}||4||{{date table sorting|15 April 1844}}||Reigate||{{sfn|Quick|2023|p=486}}
|-
|[[Earlswood railway station (Surrey)|Earlswood]]||{{cvt|21|mi|50|ch}}||2||{{date table sorting|30 April 1849}}|| ||{{sfn|Quick|2023|p=175}}
|-
|{{rws|Salfords}}||{{cvt|23|mi|37|ch}}||2||{{date table sorting|8 October 1915}}|| ||{{sfn|Quick|2023|p=402}}
|-
|{{rws|Horley}}||{{cvt|25|mi|60|ch}}||4||{{date table sorting|12 July 1841}}|| ||{{sfn|Quick|2023|p=247}}
|-
|{{rws|Gatwick Airport}}||{{cvt|26|mi|47|ch}}||7||{{date table sorting|28 May 1958}}|| ||{{sfn|Quick|2023|p=205}}
|-
|{{rws|Three Bridges}}||{{cvt|29|mi|21|ch}}||5 (4 for main line)||{{date table sorting|12 July 1841}}||||{{sfn|Quick|2023|pp=448-449}}
|}