Infraco SSL Metropolitan, Circle and Hammersmith & City Lines
Circle is 22.5km, overall nearly 100 route km of railway, some of it shared between lines, covered way 30 single track km.
Paddington to Farringdon, opened on 10 January 1863, was the world’s first underground railway. It was needed because the Great Western Railway’s terminus at Paddington was remote from the City and prompted a rash of underground railway construction.
The original mainline terminii had been built on the edges of the most built up areas of the capital but were linked by what is now the Circle Line by 1884.
The Met and Hammersmith became radial routes as well. These early subsurface lines are typically covered way with deep retained open cuts at regular intervals for ventilation of exhaust from the original steam locomotives.
Complex assemblies of brickwork, concrete, cast iron, wrought iron and steel underpinning old buildings and sewers, and supporting new developments characterise these routes.
District Line
Overall 64 route km, covered way 38 single track km.
The District has similar characteristics to Met and H&C. The central part of the route includes the southern arc of the Circle Line. Much of this was created in 1870 along with the Victoria Embankment of the Thames – a huge conduit doubling as a floodwall and carrying not only Sir Joseph Bazagette’s famous interceptor sewer, but also a two track railway, and a road on top.
East London Line
Overall 8 route km – covered way 3 km. Railway also includes the Brunels’ original Thames Tunnel which was about half a century old when the first trains ran through in 1884.
ELL features very deep cut and cover sections, some built as brick barrels.
Massive inflows of water occur on the approaches to the Thames Tunnel which, itself, was very watertight even before the controversial insitu concrete relining of mid-1990s.
Infraco BCV Bakerloo Line
Overall 23.2 route km, covered way 1km, deep bored tunnel 11km x 2, in tunnel from Elephant & Castle to Queens Park.
Opened 1906 from Baker Street to Waterloo after more than eight years construction dogged by insolvency of the original promoter. The Elephant opened the same year and an extension to Queens Park in 1915.
Tunnels’ cast iron bolted lining almost entirely in sound London Clay except under the Thames where 2 bars of compressed air was needed to stabilise water bearing gravel.
Central Line
Overall 74 route km, covered way 28km, deep bored tunnel 25.5km x 2, in tunnel from White City to Leyton and from Leytonstone to Newbury Park.
The Twoppenny Tube was the most successful of the early deep level lines when opened in 1900 from Bank to Shepherd’s Bush.
The free wayleave allowed for tunnelling under streets resulted in a high speed straight line running beneath Oxford Street with stations built on peaks to assist braking and acceleration.
But at Bank, the legacy of the street alignment is a cumbersome over-and-under station on a sharp curve.
Original undersized tunnels were enlarged piecemeal in 1938-40. Eastern extensions from Liverpool Street, begun in 1936 and which were tunnelled through difficult loose strata, were used first as armaments factories and shelters.
Victoria Line
Overall 21 route km, covered way 1km, deep bored tunnel 19.5km x 2. All tunnel except depot.
First new central London route in 60 years and a 1960s inter-pretation of the Tube, Victoria Line opened 1968 to 1971 with fully automatic train operation. Machine excavated tunnels weave in three dimensions on large radius curves regardless of street layout above.
Alignment is designed to suit high speed running between stations arranged wherever possible to give useful cross platform interchanges with older lines.
Waterloo & City Line
Overall 2.4 route km in twin bored tunnels with complex covered way section under Waterloo.
London’s second deep level line was opened in 1898 by the London & South Western Railway to carry its commuters to Bank.
It remained outside the LT system, and a curious antique, until 1994. Cramped twin tunnels weave under the Thames carrying shuttle service. Nicknamed the Drain.
Infraco JNP Jubilee Line
Overall 36 route km, covered way 1km, deep bored tunnel 19km x 2. Tunnel from Finchley Road to near Canning Town. Began in 1939 as a tunnelled branch of the Bakerloo from Baker Street to Finchley Road linking onto surface section of Metropolitan to Stanmore.
A short section from Baker Street to Charing Cross was started on site in 1971 as the Fleet Line. It opened in 1979 renamed as the Jubilee Line – with little fuss made about the eight years taken – or that it missed the Queen’s Jubilee by two years. T&TI readers know more than anyone about hugely complex Green Park to Stratford extension which took less time to build.
Northern Line
Overall 58 route km, covered way 1km, deep bored tunnel 39km x 2, tunnel from Morden to East Finchley via Bank is longest on system at 27.8km. Hamstead branch is deepest below surface, 67.4m under Holly Bush Hill.
Really a complete railway system on its own the Northern has two branches crossing the central area and three in the northern suburbs. It started as the original deep level Tube railway, the City & South London opened from Stockwell to King William Street in 1890. Some of C&SLR’s small diameter tunnels were later bypassed, others were laboriously enlarged to standard Tube size between 1922 and 1923. Difficult waterlogged ground required use of compressed air for some of this work and contributed to a major inundation which completely filled the running tunnel near Elephant & Castle.
At this time, north of the river, a highly complex undergound flying junction involving six separate running tunnels was built for the interchange at Camden Town.
Piccadilly Line
Overall 71 route km, covered way 7km, deep bored tunnel 31km x 2.
Began with Finsbury Park to Hammersmith Tube. Took four years to build and opened in 1906 following a tortuous alignment under the West End. In the 1930s it was extended in tunnels to Southgate with northern terminus at Cockfosters and to Hounslow in the west on the surface. Then in 1970s it went further from Hounslow West largely in cut and cover to the airport perimeter, initially to Heathrow Central at deep level and later extended to a loop under the airport.
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