Inside a Holland Tunnel ventilation tower Underground Canal

L ocation: Lancashire County and Manchester, England Completion Date: 1776 Length: 52 miles Purpose: Canal

Setting: Rock Materials: Brick Engineer(s): John Gilbert, James Brindley

Beneath the old county of Lancashire, England, lie 52 miles of underground canal. It is considered to be an engineering masterpiece of the 18th century and it serves as a monument to the area’s industrial past.

F rancis Egerton, the third Duke of Bridgewater, wanted a canal to transport coal from his mines at Worsley to Manchester, a distance of 10 miles. He commissioned John Gilbert and James Brindley to build the Bridgewater Canal. Completed in 1761, the highly successful canal extended deep into the coal field and became a much more efficient way to transport coal from the country to the city. The Bridgewater Canal cut the cost of coal in Manchester in half.

Work started in 1759 as small teams of skilled miners cut into rock by hand, using only picks, hammers, shovels, and drills. Later on, they used gunpowder to blast through the hard ground. The canal was carved at a downward sloping angle. That design allowed gravity to pull mining boats through the majority of the long, underground chambers. In 1776, the canal was extended an additional 30 miles, from Manchester to Liverpool. Years later, numerous canals were added, creating the longest underground canal system in the world.

Thames Tunnel

L ocation: London, England Completion Date: 1843 Length: 1,200 feet Purpose: Pedestrian/Subway Setting: Underwater Materials: Brick Engineer: Sir Marc Isambard Brunel

B y the early 19th century, London, England was a prospering city. Several bridges crossed the Thames River but more were needed. The British decided to construct a new structure: a tunnel under the Thames River. Unfortunately, the tools of the day (explosives and power drills) were no help for building tunnels through soft, watery ground at the bottom of the river. Several attempts had been made to dig a tunnel beneath the Thames River, but they were all unsuccessful. It was until 1825 when a French engineer named Marc Isambard Brunel finally found a way to do it.

Brunel invented the tunnel shield, a giant iron box that could be pushed forward through soft soil. Diggers worked from 36 individual cells in the box and faced a wall of removable wooden planks. Each digger removed one plank at a time, scooped out about four inches of muck, and then quickly replaced the board. The shield was pushed forward by hydraulic jacks, and the whole process was repeated. While the iron shield held up the soft soil, workers lined the tunnel walls with brick. But the wooden planks were too weak to support the soft, watery soil, and the entire tunnel flooded five times. Methane and other pollutants in the soil caused unexpected explosions and deaths in the tunnel. Finally, 18 years after construction began; Brunel’s tunnel shield emerged on the other side of the Thames, proving for the first time that it is possible to carve a tunnel underwater. By 1965, the Thames Tunnel was converted to railway use. Today, the Thames Tunnel is part of the London Underground, also called “The Tube.”

1.22. Robert Hulse, director of the Brunel Museum, takes us on a tour of the Thames tunnel. He describes many interesting facts about the Thames Tunnel which is considered to be the eighth wonder of the world. Listen to him and try to catch some new facts for you.

Click here to watch the video: http://www.guardian.co.uk/culture/video/2010/mar/12/thames-tunnel-rotherhithe-robert-hulse

1.23. Click here to watch the video: http://www.youtube.com/watch?v=cp5xzmTP-CA&feature=related

While watching the video, try to comment every picture.

Unite 2. Planning. Types of Tunnels and Construction Methods.