The Blackwall Rock was a reef in the River Thames near Blackwall in East London at short distance upstream from Blackwall Stairs and between the entrances of the West and East India Docks. The rock provided a useful shelter for moored vessels, but also proved a hazardous obstruction to river navigation as it was sometimes less than 3 feet (1 m) below the surface at low tide.
The entrance to the West India Docks, just to the south-west of the rock, was substantially obstructed by the reef upon the docks' opening in 1802. In 1803, Robert Edington surveyed the rock estimated its dimensions as 600 by 150 feet (183 m × 46 m). An 1846 report by the Tidal Harbours Commission described it as an outcrop of plum-pudding stone.
Early attempts to break the rock with explosives were largely unsuccessful. William Jessop was engaged by Trinity House to undertake the rock's removal which he did using a chisel, operated from a barge much as with pile driving. This method successfully reduced the height of the rock by 15 feet (4.6 m), after which a cylindrical coffer dam was employed to allow workers' access to remove rubble.
James Henry Greathead (6 August 1844 - 21 October 1896) was a civil engineer known for his pioneering development of tunnelling techniques and for his work on London's underground railways. In 1869, working under Peter W. Barlow, he became engineer in charge of driving the tunnel of the Tower Subway under the River Thames using a tunnelling shield he designed based on Barlow's own slightly earlier patented design.
Greathead developed and patented a number of improvements to the Barlow shield and the improved design carried their joint names. Greathead also developed the use of a segmented cast iron lining for the circular tunnel, erected in sections from which the shield was jacked forward. Greathead was then involved in the planning and construction of a number of railways in Britain and Ireland, until, in 1884, he was appointed engineer for the City and South London Railway, the world's first underground electric railway when it opened in 1890. Greathead subsequently worked on the Waterloo and City Railway, the Liverpool Overhead Railway and the early planning of the Central London Railway. (Full article...)
Image 2London Underground A60 Stock (left) and 1938 Stock (right) trains showing the difference in the sizes of the two types of rolling stock operated on the system. A60 stock trains operated on the surface and sub-surface sections of the Metropolitan line from 1961 to 2012 and 1938 Stock operated on various deep level tube lines from 1938 to 1988.
Image 4Arguably the best-preserved disused station building in London, this is the former Alexandra Palace station on the GNR Highgate branch (closed in 1954). It is now in use as a community centre (CUFOS).
Image 5The original Hampton Court Bridge in 1753, the first of four on the site.
Image 10The multi-level junction between the M23 and M25 motorways near Merstham in Surrey. The M23 passes over the M25 with bridges carrying interchange slip roads for the two motorways in between.
Image 27Sailing ships at West India Docks on the Isle of Dogs in 1810. The docks opened in 1802 and closed in 1980 and have since been redeveloped as the Canary Wharf development.
Image 33The newly constructed junction of the Westway (A40) and the West Cross Route (A3220) at White City, circa 1970. Continuation of the West Cross Route northwards under the roundabout was cancelled leaving two short unused stubs for the slip roads that would have been provided for traffic joining or leaving the northern section.