The Thames Tunnel

The Thames Tunnel

When it first opened in 1843 the Thames Tunnel was described as the Eighth Wonder of the World. People came from far and wide to see the first tunnel under a river anywhere in the world.

On the opening day, fifty thousand people descended the staircase and paid a penny to walk through the tunnel. By the end of the first three months there were a million people, or half the population of London. In its day, this was the most successful visitor attraction in the world.

In the age of sail and horse-drawn coaches, people came from all over the world and bought souvenirs and listened to the entertainment in the cross-tunnel arches.

The idea, of course, was not entertainment but to move cargo and turn a profit. So what happened?

The Need For A Tunnel

The proposal to build the tunnel had to take account of the sailing ships on the River Thames. The Port of London was the busiest in the world and the hub of trade across the British Empire. Any bridge built would have to allow ships with masts over 100 feet tall to sail under them, and the technology of Tower Bridge’s lifting bascules was not available to these early engineers.

A horse could not pull a loaded cart up a very steep hill, and to get 100 feet up into the air at a gentle gradient the approach ramps would have to be so long as to be impractical.

So it was that Marc Brunel proposed a crossing under the Thames using a tunnelling shield, a piece of equipment that would support the tunnel’s walls and roof as it was dug out, giving the bricklayers time to line the tunnel and create a solid structure. Horses pulling their loaded carts would descend on giant spiral ramps in new shafts 200 feet wide.


Work started in 1825 but even with the tunnelling shield this was dangerous work digging under the River Thames.

The shield was rectangular with 12 digging positions across its width and three digging positions on top of each other, allowing 36 miners to work simultaneously. In front of each miner a series of horizontal boards held in place by metal poles. The miner would unscrew the top poles, remove the board to expose the earth, dig to a depth of four inches, replace the board, replace replace the metal poles and take out the ones below. Dig to four inches, replace the board, replace the poles and start again. When he had completed the whole wall, and the man above and below had done the same, the whole row would be pushed forwards using screw jacks. Bricklayers working behind them made everything secure and the process began again. Thames Tunnel was dug in four inch strips by miners using short handled spades.

Working in the tunnel the air quality was appalling with the workers frequently being dragged senseless up to the surface to recover in the fresh air. Conditions were also very damp with water constantly coming in from the River Thames above. But worse, this was the River Thames before Sir Joseph Bazalgette and his sewer system for London. The River Thames was no better than a sewer, and the sewage entering the tunnel gave off methane gas which was frequently set alight by the candles that provided a dim light for the workers – there were no miner’s safety lamps in the Thames Tunnel.

The Tunnel flooded five times during construction, and in the worst flood six men drowned and Isambard Kingdom Brunel barely escaped with his life. As well as danger to life, each flood caused delays. A small boat would drop thousands of clay bags into the river, pumps worked hard in the Tunnel to empty the water and then the terrible business of clearing the debris before work could begin again.


In 1843 the tunnel finally opened, but for pedestrians not the horses and carts carrying cargo.  The tunnel had taken so long to build there was simply no money to build the two large shafts with spiral ramps that the horses and carts would use to descend and ascend.

Even under construction, the Tunnel was a tourist attraction, and when complete millions of people came to pay a penny to walk through the ‘Eighth Wonder of the World’


The East London Railway company bought the tunnel in 1865 with the intention of digging new tunnels to link up from the North and South to link the Thames Tunnel to the national railway network. Four years later, in 1869, trains started to run through the tunnel meant  for horses and carts. For the first time the tunnel was doing what it was intended to do – carrying freight across the river.

In 1869 electric trains had not yet appeared on the national network, so the trains running through the tunnel were hauled by steam engines. Entering the tunnel the trains would go downhill towards the low point at mid-river before starting the hard climb back up to the surface. The harder a steam engine works the more smoke it produces. In railway tunnels on land there are frequent shafts to allow the smoke to escape to the surface. No ventilation shafts could be built in the river so The Thames Tunnel was full of smoke making life very unpleasant for the steam engine drivers and firemen.

In 1913 the railway was electrified and incorporated into the London Underground as the East London Line, making the Thames Tunnel the oldest tunnel in the oldest underground system in the world. This is the birthplace of the tube!

London Overground

A hundred years later, the line was closed as part of an ambitious scheme to build an orbital railway for London. The Thames Tunnel is now part of the London Overground,  reducing journey times and congestion in the centre of the city. This very busy and successful railway is the latest addition to the capital’s transport system, incorporating The Brunels’ Tunnel, oldest river tunnel in the world…

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