Site Records

Site Name: Tower Subway

Tooley Street, London S.E.1
Tower Hill, London E.C.3
OS Grid Ref: TQ333805

The Tower Subway's chief claim to fame is that it is the world's first tube railway, that is, an underground railway constructed in a tube rather than in a brick tunnel. That said, given the number of admirable websites already devoted to the Tower Subway (listed at the end of this survey), one might query the need to create another one. The answer is simple! Here you can read plenty of interesting material unavailable on the other sites, drawn almost entirely from primary sources rather than articles based on earlier articles. If you don't have time to read all the text just enjoy the illustrations. And now read on...

PERIOD DESCRIPTIONS
The Tower Subway consists of an iron tube, 7 feet in diameter and about 1235 feet in length, laid some 18 feet below the bed of the Thames. It runs between Great Tower Hill on the north side of the river, and Tooley Street on the south. It belongs to a Limited Liability Company, and was opened for tramway traffic on the 12th April, 1870. Being a losing speculation, the tram cars ceased to run on 7th December, 1870; but it was opened for foot-passengers (toll, one halfpenny) on the 24th of that month, and the Company have successfully continued it only as such. It is reached at each end by a spiral staircase of 96 steps. The Subway is well lighted up with gas, the average heat by the thermometer being 65 degrees Fahr. Those, however, who are afflicted with chest complaints should not attempt to make use of it, owing to the extreme closeness of the atmosphere and the limited space in the tube, which renders stooping necessary. It is open from 5.30 AM. till midnight. [Collins' Guide to London and Neighbourhood, no date.]

Cross section of tube

The tunnel commences at Tower Hill, where a hoarding encloses a small square of ground, not larger than an ordinary sitting-room, for which, however, the Government made the Company pay at the rate of about £240,000 an acre. In the centre of this is a little circular shaft, about fourteen feet diameter and sixty feet deep, and at the end of this, facing south, a clean, bright, vaulted chamber, which serves as a waiting-room. At the end of this chamber is the tunnel, a tube of iron not unlike the adit of a mine, which, in its darkness and silence, heightened. by the knowledge that. this grim-looking road runs down deeply below the bed of the river, gives it at first sight anything but an inviting appearance.

The length of the whole tunnel is about 1,340 feet, or as nearly as possible about a quarter of a mile. From Tower Hill it runs in a south-west direction, and, passing under Barclay's brewery, opens under a shaft similar to that at entering, but only fifty feet deep, and out of this the passengers emerge within a few yards of Tooley Street, close to the railway station. [Old and New London, by Walter Thornbury (1897)]

LOCATION

The northern entrance kiosk of the Tower Subway is seen in this aerial view (the continuation towards the other side of the river is unfortunately cropped). From London Illustrated by Twenty Bird's-Eye Views by Herbert Fry (1894).

CONSTRUCTION
The works were begun on February 16th 1869, by 'breaking' ground for the shaft on the north side of the river; in February 1870, numerous visitors were conveyed from one shaft-head to the other. [Old and New London, by Walter Thornbury (1897)]

A tunnel, crossing beneath the river from Tower Hill to Tooley Street, near the London Bridge railway station, has been constructed in the present year [1869]. It is not a brick archway, but a circular iron tube, 7 ft. in diameter, laid deep in the clay of the river bed. The engineer is Mr. Barlow, Jnr., son of the Mr. Barlow who constructed the Lambeth Suspension Bridge.

The contractor is Mr. Greathead; and the cost, it is said, will scarcely exceed £16,000. The works, of which we give several illustrations, may be approached from Tower Hill by going down a circular iron shaft, 10 ft. in diameter and 60 ft. deep. The upper part of the shaft is lined with powerful rings of cast iron, the lower part with ordinary brickwork, which will be coated with glazed tiles. There the visitor sees before him an iron tube 7 ft. in diameter, and lined closely along the inside with iron :flanges, or rims, nearly 2 in. deep. This tube has much the appearance of one of the large clean main­drainage sewers, except that it is built of iron and has a greater incline and curve. Candles, few and far between, twinkle in the distance and just make darkness visible. The whole length of the tube is 1320 ft.

The shaft at Tower Hill

Advancing the shield

A rather steep incline of 1 in 40, curving from north-east to south-west that is to say, from Tower Hill to near Tooley Street soon leads the visitor from the London clay beneath the land to the London clay beneath the water, and a difference of temperature between the two is at once perceptible. It is so dry throughout that every drop of water wanted for the works has had to be sent down in buckets. The tunnel, from the north to the south shores, makes a dip to pass under the water and its line of curve is rather deep. At its nearest point to the river water it has a thickness of not less than 22ft of London clay between the bed of the river and the top of the tube, while at its furthest point it has a thickness of 32 feet. Sounds from above are distinctly heard in the tunnel.

The shield which is advanced to cover the driving of the tunnel is a light circular piece of mixed cast and wrought iron, weighing 2 1/2 tons, and having an outer diameter of 7 ft. 3 in. The tube of the tunnel itself is built by means of three segments of a circle of cast iron, each of great strength and weighing 4 cwt., with a centre key-piece at the top weighing 1 cwt.

Putting the castings

Each segment or ring when bolted together is only 18 in. long, but no fewer than six of these rings are bolted on in every twenty four hours, so the tunnel is advancing at the rate of 9 ft. a day. As the cap or shield is pushed on for a length of 18 in. it leaves within its tube or rim a space 1 in. greater all round than that occupied by its own tube on the outside. This, therefore, leaves ample room to fit in the segments of the tunnel-tube easily. It is done very rapidly. The bottom segment is laid in its place, and the two side segments above it, and between these at the top the key-piece is slid in. Between the long horizontal flanges a layer of white pine is placed before they are screwed close up, and it is to be regretted that some such indestructible material as gutta-percha was not chosen for this work.

The spaces between the circular flanges of each segment are regularly caulked in with tow and cement. Still, the shield or cap is 1 in. wider all round than the diameter of the tunnel-tube within it, which comes afterwards to occupy it, leaving an opening of that space between the clay and the iron. This interstice, when the segment-ring is fixed, is closed by pumping in blue lias cement, which, as it quickly sets, forms a ring of stonework, not only impervious to the water, for that, indeed, the tube itself is, but impervious to the action of water on the iron tube itself, which is a very important matter. It takes some time to explain all these details, but in practice they are an very quickly done.

The tunnel from the heading

Thus the men excavate the ground in front of the shield, move forward the shield and fill in another segment behind it every four hours and as the work is continued day and night in three relay gangs working eight hours each spell, it follows that the tube advances 9 ft. every twenty four hours.

This circular tunnel is not intended for foot passenger traffic; it is meant for a tramway of 2ft. 6 in. gauge, on which is to run a light iron omnibus of 10 1/2 ft. long, 5 ft. 3 in. wide and 5 ft. 11 in. high. This will accommodate fourteen people with the most perfect ease. Ordinary lifts will take them down and up the shafts at each end, and at the end of the shaft the 'bus' will be waiting. For the first hundred feet or so the omnibus will be pulled by a rope fixed to a stationary engine; after that it will descend by its own velocity down the incline and up the incline on the other side to the foot of the shaft. The whole transit, including time for descent and ascent, is not to exceed three minutes. [Illustrated London News, 30th October 1869]

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