The Rotherhithe Tunnel is a road tunnel crossing beneath the River Thames in East London. It connects the Ratcliff district of Limehouse in the London Borough of Tower Hamlets north of the river to Rotherhithe in the London Borough of Southwark south of the river.
It was formally opened in 1908 by George Prince of Wales (later King George V), and Richard Robinson, Chairman of the London County Council.
Designed by Maurice Fitzmaurice, the Engineer to the London County Council, the tunnel's construction was authorised by the Thames Tunnel (Rotherhithe and Ratcliff) Act of 1900 despite considerable opposition from local residents, nearly 3,000 of whom were displaced by the tunnel works
The work took place between 1904 and 1908, executed by the resident engineer Edward H. Tabor and the contractors Price and Reeves at a cost of about £1 million. The tunnel was excavated partly using a tunnelling shield and partly through cut-and-cover methods. The entrance arches of the tunnel are in fact the cutting edges of the original tunnelling shield, which measured 30 feet 8 inches in diameter, forming in effect a loading gauge for the tunnel.
The Rotherhithe Tunnel consists of a single bore, 4,860 feet long, carrying a two-lane carriageway 48 feet below the high-water level of the Thames, with a maximum depth of 75 feet below the surface. Four shafts were sunk alongside the tunnel to aid construction and to serve later as ventilation and entrance shafts. The two riverside shafts, built in red brick with stone dressings, were fitted with iron spiral staircases to serve as pedestrian entrances. They are now closed to the public (the roofs were damaged during WWII, and the iron staircases became dangerous), and currently the only entrance to the tunnel is via the main portals at each end (the bases of the staircases can still be seen as you pass through the tunnel).
The tunnel is entered via a sloping brick-lined open-air cutting at each end, leading to the entrance portals, followed by a short cut-and-cover section of tunnel until the first of the tunnel's four shafts are reached. The tunnelled section is situated between shafts 1 and 4, measures 3,689 feet long and is lined with cast iron segments. At the time of its construction, the tunnel was said to be "the largest sub-aqueous tunnel in existence".
The Rotherhithe Tunnel was originally designed to serve foot and horse-drawn traffic passing between the docks on either side of the river. This accounts for some of its more unusual design features. The roadways are narrow, with each lane only some 8 feet wide, and two footways of between 4 and 6 feet wide on either side. The tunnel is shallow, with a maximum gradient of 1 in 36 (2.8%), to cater for non-mechanised traffic. Its route includes sharp, nearly right-angled bends at the points where the tunnel goes under the river bed. These served two purposes: avoiding the local docks on each side of the river, and preventing horses from seeing daylight at the end of the tunnel too early which might make them bolt for the exit.
Sources of Information
-  Wikipedia