London, the capital of England and the United Kingdom, is a modern-day city with great historical significance too. One of the busiest cities in the world, it has been that way for centuries as it was at the heart of the British empire.
If we turn back our clocks by two centuries, London was, as is today, one of the busiest places on Earth. The port, especially, was a huge bottleneck with cargoes that had travelled thousands of miles awaiting the slowest portion of their journey after reaching London. With the narrow London Bridge built in the 12th Century serving as the only crossing across the River Thames, London was home to one of the world’s worst traffic jams of the time.
Crossing point
By 1820, it was obvious to everyone that the city needed another crossing point. As building a second bridge further downstream would have reduced shipping access, the only available alternative, even though it seemed impossible, was building a tunnel.
Tunnelling under a major river was unheard of. Preventing the tunnel from being flooded during the construction stage seemed to be an insurmountable problem. There had been a number of different attempts to tunnel under the Thames, including one by British inventor and mining engineer Richard Trevethick in 1807, but all of them ended as failures.
Inspired by nature?
It needed an engineering genius in the form of Marc Isambard Brunel to recognise the difficulty of the task at hand and develop suitable machines to deploy at scale. Even though he neither had interest nor had prior knowledge in the subject, it is believed that he recognised that a shipworm’s burrowing technique when adapted would afford a new way of tunnelling.
Portrait of Marc Isambard Brunel . | Photo Credit: Check source link for mandatory credit
The shipworm, which is in fact a mollusc, burrows into the wooden hull of ships. A hard outer shell around its gnawing jaws and head protects its otherwise soft body as it bores through the wood. Brunel figured that he could build a tunnelling device on this basis.
The tunnelling shield
Brunel’s tunnelling shield consisted of a grid of iron frames that could be pressed against the tunnel face. Poling boards, which were a set of horizontal wooden planks, supported the iron frames and prevented the tunnel face from collapsing. It wasn’t until 1825 that this machine, which was around 11m across and 6.5m in height, was completed.
Funded by private investors, the project to build the Thames Tunnel began on March 2 1825, with the first stone being laid at the Rotherhithe shaft entrance. Little did they know that there was another 18 years worth of toil ahead of them.
With the tunnelling shield allowing 36 people to work at a time, the idea was to have them working on three levels, removing a wooden board in front of them, excavating about 10cm of the earth, before replacing the board again. The tunnelling shield was brought in for work once the vertical shafts had been dug and the horizontal tunnelling under the river began by November.
Moves at a snail’s pace
Even though the shield work, work was both stalled and moved at a slow pace due to various reasons. The fact that the river had been used for dumping and as a sewer for nearly a thousand years meant that the obnoxious smell was often overpowering, forcing people to even faint at the face of the shield.
There were a number of times when flooding did take place, including an occasion when lives were lost. Irrespective of the seriousness of the flooding, deploying the shield and resuming work was always a slow process. Improved versions of the shield were built, but the rate at which work progressed remained at a snail’s pace owing to the gargantuan nature of the task.
Costs, naturally, skyrocketed and the government stepped in only in 1934 with a cash injection. Nearly a decade since the start of the project, it had gathered significance and had become a matter of prestige and national importance.
The tunnelling stage was finally completed in November 1840 and Brunel was knighted for his efforts by Queen Victoria, who was impressed by the engineering feat, in 1841. The final construction was completed by 1842 and the Thames Tunnel was officially opened on March 25, 1843.
An illustration showing the Thames Tunnel as a pedestrian plaza. | Photo Credit: Check source link for mandatory credit
Lavishly decorated interiors
Measuring 396m in length, 11m in width and 6m in height, the tunnel’s greatest depth was 75 feet (23m) below the surface of River Thames. As was the case during those times, the interiors were lavishly decorated, with elements of Roman architecture in the Neoclassical style.
As the tunnel had gone well beyond the budget, the initial plans to allow horse-drawn carriages were shelved as the ramps needed for them were never built. It was opened as a tunnel for pedestrians, and it turned out to be a popular attraction immediately.
Paying a penny to enter the tunnel, over 50,000 people walked the tunnel right on the first day. That number jumped up to a million within the first 15 weeks of its opening and 2 million in nine months. The novelty, however, soon wore off, especially for the locals, and the tunnel was less and less frequented, as early as the 1850s.
Still in operation
The East London Railway Company bought the tunnel in 1865 and the tunnel was set to be used for the passage of trains. It was another four years before the first train plied through the tunnel in December 1869. The tunnel was used by the London Underground from 1913.
Nearly 200 years after the construction of the Thames Tunnel began, the tunnel still remains in operation as part of the London Overground network. While the tunnel stands testament to the work done by all those people over an extended period of time, the tunnelling shield has proved to be a bigger gift to humankind through this entire project as it still remains widely used in almost all underground construction projects.
