ENGINEERING & THE CITY

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The City of London provides many opportunities to view how engineering has impacted the City and vice versa. Yesterday we undertook a walk to a few of the key sites that can be visited.

Starting at the Tower of London, take the unusual step of turning your back on the building (river to your left) and you will spot a doorway in a brick kiosk inscribed The London Hydraulic Power Company. This tunnel started life as the entrance to the Tower Subway. Conceived as a steam powered cable-hauled cable car the project was remarkably unsuccessful in all but the tunnelling. After only a few months it closed, the tracks were removed and for more than 20 years it became a paying pedestrian tunnel. A million people a year used it despite the rancid air caused by the gas lighting. The tunnel was then used, until the 1970s, by the Power Company for their mains. It was damaged during the Second World War by a bomb that exploded on the river bed very close to the tunnel’s roof. The shock of the blast compressed the tunnel radially but the tunnel’s lining was not penetrated. After the Power Company went bust the tunnel was still used for mains. Today, it carries telecommunication cables. The cable car was the world’s first tube railway. If you look at your feet when walking the City, you may well see LHP on valve covers.

Walking to the riverbank: turn left and you have Tower Bridge, a Victorian example of mechanical and civil engineering coming together to provide a trade route from north to south without disrupting river trading activities (the bridge raises because large shipping had to get through to the docks); and turn right and you have London Bridge.

Tower Bridge took 8 years, 5 major contractors and 432 construction workers to build. Although the Bridge appears to be brick built this is in fact cladding, concealing steelwork underneath. Tower Bridge was the largest and most sophisticated bascule bridge ever completed, when built. These bascules were operated by hydraulics, using steam to power enormous pumping engines. There were six massive accumulators, meaning power was available to lift the Bridge as and when needed. The accumulators fed the driving engines, which drove the bascules up and down; the bascules only took about a minute to rise to their maximum angle of 86 degrees. They still run on hydraulic power but since 1976 they have been driven by oil and electricity.

The original London Bridge was slightly forward of where it sits now and has Roman origins; the next fixed crossing was finished in 1209 and lasted over 600 years; the following incarnation was opened in 1831, it was sold in 1968 and relocated to America; and so to the current structure, it comprises three spans of pre-stressed concrete box girders, a total of 928 feet long, and was opened in 1973.

Walk towards London Bridge and up to pavement level, turn right and then left and you will be at the Monument (to the rebuilding of London after the Great Fire). The building on your left features a small plaque; this records the location of King Edward Street station. The City and South London Railway ran from here to Stockwell. It was the first railway tunnel to be excavated using a tunnelling shield rather than the cut-and-cover method. The shield was cylindrical and had steel blades that were forced into the soil by hydraulic rams operating at a pressure of 1,575 tonnes per sq m. The Railway was the world’s first deep-level underground passenger railway.

Now walk up King Edward Street as far as the Royal Exchange and you will find a statue of James Greathead. Greathead, was responsible for the aforementioned Railway and Tower tunnels.

Walk towards the Bank of England and turn right, on the opposite corner is the old London Stock Exchange building (now RBS). Due to modern media/communications trading floors of the face-to-face nature still practised on the metal exchange and Wall Street no longer exist in London- engineering and related disciplines have truly transformed how markets operate.

Cross the road and go up Bartholomew Lane and turn into a dead-end on the right (Founders Court). Here was the base of the Electric Telegraph Company. This was the email of the past, making quick information and message sharing possible. The Company was the world’s first public telegraph company, founded by Sir William Fothergill Cooke and John Lewis Ricardo in 1846. They purchased all the patents Cooke and Charles Wheatstone had obtained to date. In 1855 they became the Electric and International Telegraph Company. This was nationalised by the British government in 1870.

Leaving the yard continue to the end of the road and turn right, then second left down Great Bell Alley (near to the old site of the first telephone exchange), cross the road to Masons Avenue and then turn right onto Basinghall Street. Cross Aldermanbury Square and turn right and you will find yourself at London Wall. The site of the Museum of London, and the nearby Barbican, are the largest remaining elements of the Pedway (smaller sections of this raised walkway can be seen here and there within the City). The Pedway was a scheme to separate pedestrians and other road users/functions. Such a scheme had been proposed for decades but it took shape during London’s post-war reconstruction. However, it was pretty much doomed from the start due to reservations from groups such as fire and police services; also linking to existing (often historical) buildings was fraught with issues. Today the smaller sections are disappearing as the post-war buildings they are connected to are redeveloped.

Turn right along London Wall and then left at the intersection, onto Moorgate. Moorgate Station is our final stop. The tube tunnels here were built with the conventional cut-and-cover method and originally operated as the Metropolitan and City Railway. The Widened Lines, that now forms a section of the Thameslink route, ran from King’s Cross to Moorgate; it was completed in 1866 when the railway was widened from two to four tracks between King’s Cross and Farringdon and a four-track railway opened from there to Moorgate. The tracks were owned by the Metropolitan Railway but were used mainly by other railway companies. Connections to the Great Northern Railway at King’s Cross and London, Chatham and Dover Railway at Farringdon allowed cross-London services to run. There was very soon a connection to the Midland Railway at St Pancras. In the early 20th century the cross London services dwindled, although the GNR and Midland services into Moorgate survived. In 1976 the former GNR services were diverted via the Northern City Line to Moorgate, and in 1988 the cross-London route reopened for Thameslink. The line east of Farringdon closed in 2009 to allow the platforms at Farringdon to be extended to take 12-car trains.

To attend this walk yourself and learn lots more about these schemes contact David Charnick. Charnick is a qualified City of London guide with a particular interest in the role of engineering in city development and how London has prospered.

Archives, Institution of Mechanical Engineering

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