Dollis Brook Viaduct

Dollis Brook Viaduct
Dollis Brook Viaduct
	The Dollis Brook Viaduct
Coordinates	51°36′18″N 0°12′08″W / 51.6051°N 0.2022°W
Carries	London Underground Northern line
Crosses	Dollis Road, Dollis Brook
Locale	Finchley, London
Official name	Dollis Brook Viaduct, Dollis Road Viaduct, Mill Hill Viaduct
Characteristics
Design	Viaduct
Material	Brick
Total length	13 arches of 32 feet (9.8 m) span each
Height	60 feet (18 m)
No. of spans	13
History
Designer	John Fowler, Walter Brydone
Construction start	1863
Construction end	1867
Opened	22 August 1867
Location

The Dollis Brook Viaduct, also known as the Dollis Road Viaduct, Dollis Viaduct or Mill Hill Viaduct, is a

railway viaduct to the west of Finchley, North London, United Kingdom. It carries the London Underground's Northern line from Mill Hill East station to Finchley Central station. It is the highest point on the London Underground above ground level, reaching nearly 60 feet (18 m). It is located on a branch that was formerly part of the Edgware, Highgate and London Railway

.

Etymology

The official name of the viaduct is taken from Dollis Brook which it crosses. The brook was marked on an 1877 Ordnance Survey map and the name may have originated from a farm called Dollis, previously in Hendon. This was earlier named Dalys in 1563, (the) Doles 1574, Dallys 1584 and in its current form of Dollis in 1822. This probably meant "the portions or shares of land (in the common field)", from the Middle English word dole.^[1]

The name is not thought to be connected with the area of Dollis Hill, further south. Dollis Hill is thought to mean a "hill associated with a family called Dalley".^[1]

History

The viaduct was designed by

Act of Parliament in 1862.^[3]

Although built to carry two tracks, the viaduct initially carried only one. Following the construction of a branch northwards from Finchley to Barnet in 1872, the original Edgware route effectively became a branch of the newer line.^[4] In the 1920s, the London and North Eastern Railway (LNER, successor to the GNR) planned to electrify the line but work was not carried out until the 1930s when the Northern Heights plan led to the doubling and electrification of the lines. This was in preparation for a transfer of the lines to the London Underground for it to form part of the system's Northern line.

The start of the

Second World War prevented the plans being completed and only the section of the line to Mill Hill East was electrified and reopened in 1941, whilst the High Barnet branch was electrified in 1940. From this point on London Transport trains used only one of the tracks on the Mill Hill branch and the other track was soon lifted. Freight on the line lasted until 1964 when the line west of Mill Hill East was abandoned, leaving the present arrangement.^[3]^[4]

Length, span and architecture

The viaduct's 13 segmental

Amersham (Metropolitan line) in the Chiltern Hills, at 150 metres (490 ft) above sea level.^[6]

Around the viaduct

Location of the Dollis Brook Viaduct

Legend

Edgware					High Barnet
unbuilt link
Edgware (LNER)					former LNER to Mill Hill East
Burnt Oak					Totteridge & Whetstone
Colindale					Woodside Park
					Mill Hill (The Hale) (LNER)
Hendon Central					West Finchley
Brent Cross					Mill Hill East
					Dollis Brook Viaduct
					Finchley Central
Golders Green
					East Finchley

Below the viaduct can be found the

Moat Mount Open Space in Mill Hill and Hampstead Heath. This is designed to link many green spaces and wildlife corridors along the way and is approximately 10 miles (16 km) long.^[7]^[8] The geology nearby is of London Clay

with small amounts of other rock types.

An examination in the late 19th century of the railway cutting between Finchley and Hendon station found a large extent of glacial beds and fossils, and these were thought to extend as far northwest as the viaduct.^[9]