North Downs Line

The North Downs Line is a railway line in South East England. It runs for from in Berkshire to in Surrey. It is named after the North Downs, a range of chalk hills that runs parallel to the eastern part of the route. The name was introduced in 1989 by Network SouthEast, the then operator. The North Downs Line serves the settlements in the Blackwater Valley as well as the towns of Guildford, Dorking and Reigate. It acts as an orbital route around the south-west of London and has direct connections to the Great Western Main Line at Reading, the Waterloo–Reading line at, the Alton line at, the Portsmouth Direct line at and the Brighton Main Line at Redhill.
Three different operators run passenger services on the North Downs Line. Great Western Railway runs services along the entire length of the line from Reading to Redhill, the majority of which continue along the Brighton Main Line to. Southern trains between and use a section west of Redhill. South Western Railway services between the capital and Reading use the line west of Wokingham and the same company operates between Guildford and en route to.
The majority of the North Downs Line was constructed by the independent Reading, Reigate and Guildford Railway company, although the section between Guildford and Ash Junction was built by the London and South Western Railway. The line opened in 1849 and services were run from the outset by the South Eastern Railway, which took over the RG&RR in 1852. Three sections of the line were electrified by the Southern Railway in the 1930s although around remain unelectrified. In the early 21st century, infrastructure works to increase the capacity of the line were undertaken, including the provision of new platforms at Reading and Redhill.

Route

Overview

The North Downs Line is a railway line in South East England. It links Reading railway station on the Great Western Main Line in Berkshire to on the Brighton Main Line in Surrey. It serves the settlements in the Blackwater Valley on the borders of Hampshire, Surrey and Berkshire, as well as the Surrey towns of Guildford, Dorking and Reigate. It acts as an orbital route bypassing the south-west of London and has direct connections to the Waterloo–Reading line at, the Alton line at and the Portsmouth Direct line at. The 2015 "Surrey Rail Strategy" noted that 56% of passengers on the route connect to services on other railway lines and that a quarter of journeys either start or end at Reading. Around 13% of passengers travel to or from.
The name "North Downs Line" was first used in 1989 by Network SouthEast, the then operator of the line. Between Redhill and Ash, the line runs roughly parallel with the North Downs, a range of chalk hills that runs from Farnham to the White Cliffs of Dover. Between Ash and Reading, the line crosses the sands, gravels and clays of the London Basin. The steepest gradients, 1 in 96, and the summit of the line are near, where the route crosses the watershed between the Rivers Mole and Wey in Surrey. The distances along the line between Redhill and Shalford Junction, and between Ash Junction and Reading are measured from station in London.
File:A Class 450 unit crosses the River Kennet to the east of Reading station 02.jpg|thumb|right|A Class 450 unit crosses the navigable River Kennet to the east of Reading station.
The North Downs Line is double track for the entirety of its length and has a maximum operational line speed of for passenger trains. Three sections of the line, RedhillReigate, GuildfordAldershot South Junction and WokinghamReading, are electrified using the 750 V DC third-rail system. Two sections, ReigateShalford Junction and Aldershot South JunctionWokingham, together totalling, are unelectrified. The line has a W6 loading gauge, and overnight engineering possessions of up to hours are available. In 2006, Network Rail classified the North Downs Line as "congested", but, following the construction of new infrastructure, this status was revoked in 2023.

Reading to Guildford

The Reading to Guildford section of the North Downs Line is in length and has 13 stations in total. Reading and Guildford stations are managed by Network Rail and have 15 and 7 operational platforms respectively. The other 11 stations have two platforms each.,,, Wokingham, Ash and stations are managed by South Western Railway.,,, and stations are managed by Great Western Railway. The passenger train services that use this section of the North Downs Line are:

Reading to Redhill and, operated by GWR using and units
Reading to, operated by SWR using and units
and to Guildford, operated by SWR using units

West of Wokingham Junction and east of Aldershot South Junction, this part of the line is electrified using the 750 V DC third-rail system, leaving an unelectrified central section. Most services on the North Downs Line use platforms 4, 5 and 6 at Reading station, but access to other platforms is possible. The Reading station area is controlled from Thames Valley rail operating centre, the line from Earley to North Camp is controlled by Basingstoke rail operating centre, and the section from North Camp is controlled by Guildford signal box. The majority of this section has a line speed of with the exception of the approaches to Reading, Wokingham and Guildford stations, and a restriction at Ash Junction where the line curves sharply. The steepest gradient, to the west of Guildford, is 1 in 100.
The Waterloo–Reading line diverges from this part of the North Downs Line at Wokingham Junction, and a spur to the Alton line joins at Aldershot South Junction. In addition, the line passes beneath the South Western Main Line at Farnborough, but there is no longer a junction between the two. This section passes over two navigable waterways, the River Kennet and the Basingstoke Canal, as well as the unnavigable River Loddon and its tributary, the Blackwater.

Station	Mileage	Number of platforms	Managing company	Trains operated by	Opening date	Original name	Ref.
	from via	15	Network Rail	GWR SWR CrossCountry Elizabeth line
	from Charing Cross via Redhill	2	SWR	SWR
	from Charing Cross via Redhill	2	SWR	SWR
	from Charing Cross via Redhill	2	SWR	SWR GWR		Sindlesham and Hurst
	from Charing Cross via Redhill	2	SWR	SWR GWR
	from Charing Cross via Redhill	2	GWR	GWR		Wellington College
	from Charing Cross via Redhill	2	GWR	GWR
	from Charing Cross via Redhill	2	GWR	GWR
	from Charing Cross via Redhill	2	GWR	GWR		Farnborough
	from Charing Cross via Redhill	2	GWR	GWR
	from Charing Cross via Redhill	2	SWR	SWR GWR
	from via	2	SWR	SWR GWR
	from London Waterloo via Woking	7	Network Rail	SWR GWR

Shalford Junction to Redhill

Between Guildford and Shalford Junction, GWR trains use the Portsmouth Direct line to travel between the two parts of the North Downs Line. The route passes through two tunnels, Guildford Chalk Tunnel and St Catherine's Tunnel. Reversible working is available on the down line on this section of track.
The Shalford Junction to Redhill section of the North Downs Line is long and has eight stations in total. Reigate and Redhill stations are managed by Southern, but the remaining six stations are managed by GWR. Redhill has four platforms, but the other seven stations have two each. The passenger train services that use this section of the North Downs Line are:

Reading to Redhill and Gatwick Airport, operated by GWR
Reigate to via Redhill, operated by Southern

Much of this part of the North Downs Line runs immediately to the south of the North Downs escarpment, although the route deviates to the south between Chilworth and Gomshall to avoid Albury Park. Only the section between Reigate and Redhill is electrified. Between Shalford Junction and Gomshall, the line is controlled from Guildford signal box and the majority of the route to the east is controlled by Reigate signal box. Redhill railway station and its approaches are controlled by Three Bridges rail operations centre. The maximum speed on this part of the North Downs Line is.
The route crosses the Mole Valley Line immediately to the east of Dorking Deepdene, but there is no longer a junction between the two. The navigable River Wey is crossed at Shalford via a steel truss bridge, which replaced the original wooden bridge in 1902. The North Downs Line crosses the River Mole on a five-arch, brick viaduct, built when the line was constructed in the late 1840s. The A24 dual carriageway at Dorking is crossed on a steel bridge, installed in 1964.

Station	Mileage from via	Number of platforms	Managing company	Trains operated by	Opening date	Original name	Ref.
		2	GWR	GWR
		2	GWR	GWR
		2	GWR	GWR
		2	GWR	GWR		Dorking
		2	GWR	GWR		Box Hill and Leatherhead Road
		2	GWR	GWR
		2	Southern	Southern GWR
		4	Southern	Southern Thameslink GWR		Reigate