Sutton Loop Line
Sutton platform 2 looking towards West junction with the St Helier Line
Overview
Status	Operational
Owner	Network Rail
ELR	SMS1 (Streatham South Jn–Wimbledon) SMS2 (Wimbledon–Sutton)
Locale	London Boroughs of Merton and Sutton
Termini	Streatham South Jn Sutton
Stations	14
Service
Type	Heavy rail
System	National Rail
Services	Thameslink Southern
Operator(s)	Govia Thameslink Railway
Depot(s)	Bedford Cauldwell for Thameslink Selhurst for Southern
Rolling stock	Class 377 "Electrostar" Class 700 "Desiro City"
Technical
Number of tracks	2 1 bi-directional line at Wimbledon
Track gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge
Operating speed	Maximum 60 mph [1]
Route map (Click to expand)

v t e Sutton Loop Line
Legend
mi+ch Portsmouth line to South Bermondsey Junction Streatham Brighton Main Line Victoria–Brighton 0+00 Streatham South Junction Portsmouth line via Mitcham Junction 0+76 Tooting Tooting Junction Tooting, Merton and Wimbledon Railway to Merton Park 2+18 Haydons Road South West Main Line to Waterloo 3+07 7+21 Wimbledon Wimbledon–West Croydon line to West Croydon 7+51 Wimbledon West Junction South West Main Line to Weymouth 8+13 Wimbledon Chase 8+61 South Merton 9+32 Morden South 9+69 St Helier 10+67 Sutton Common 11+47 West Sutton Portsmouth line via Mitcham Junction 12+50 Portsmouth line to Horsham │Sutton Epsom Downs line to Epsom Downs │ London & Croydon Rly to London Bridge

The Sutton Loop Line,^[1] also known as the Wimbledon Loop,^[2] is a railway line that diverges from the Portsmouth Line^[1] at Streatham South junction and rejoins it near Sutton station. Trains leave southwards from Streatham to enter the loop and then return going northwards. The short section between West Sutton station and West junction is known as the "Wall of Death",^[3] possibly due to the very steep concrete walls to the cutting on both sides and the sharpness of the curve which resemble the motorcycle ride at a funfair.

Stations

In a clockwise direction round the loop, the stations are:

• Sutton
• West Sutton
• Sutton Common
• St Helier
• Morden South
• South Merton
• Wimbledon Chase
• Wimbledon
• Haydons Road
• Tooting

Infrastructure

Traction current is supplied at 750 volts DC via the third rail. The supply for this is overseen by Selhurst Electrical Control Room.^[1] Signalling is Track Circuit Block with multiple aspect colour light signals, controlled from Three Bridges rail operating centre. The line is double track throughout, except where a short bi-directionally signalled single line section passes through Wimbledon station platform 9. Originally the Down St Helier Line used platform 10 at Wimbledon, but this is now used for the Tramlink terminus which currently comprises a single platform at the southern end, split into two sections so two trams can be held at the same time.^[4]

History

Services

Thameslink

Thameslink runs services from St Albans, via Blackfriars round the loop. Clockwise services are described as "Sutton via Mitcham Junction" and anti-clockwise as "Sutton via Wimbledon". Occasionally, during service disruption or when the core section of the Thameslink route is closed, Sutton Loop services start and end at London Bridge 'low level' station (i.e. the terminating platforms, 10–15).

Recent proposals were to increase the frequency of the Thameslink service by terminating at Blackfriars. This would have allowed the trains through the core section to be replaced with longer trains which could not use the loop, but this did not proceed due to objections from loop passengers about the withdrawal of their through service.^[5]