Our network | 14 Feb 2023

The history of Vodafone’s 153-year-old tunnel under the Thames

In August 1870, a cable-hauled wooden carriage in a tunnel under the River Thames was opened to the public. It helped transport Londoners from one side to the other, but today the tunnel is being used as part of the Vodafone network.

The Victorians were responsible for pioneering one of the most under-appreciated means of modern communication – sub-sea cables – but their legacy also underpins your mobile signal and broadband connection in other, even more unexpected ways.

In several places across the UK, Vodafone uses historic buildings and other structures to support its mobile and fixed line network, many of which have had remarkably quirky lives long before they entered Vodafone service. 

In doing so, Vodafone UK helps preserve these architectural artefacts for future generations.

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There’s little evidence of the Tower Subway above ground as it runs underneath the River Thames. This 406-metre-long tunnel is nonetheless an important part of Vodafone’s network in London, housing fibre-optic cables that carry data to and from Vodafone’s masts as well as for its business customers. 

Chris Arnold, a project manager at Jascom Electrical Contractors Ltd, told Vodafone UK news: “Jascom helps maintain the tunnel because it’s quite old and it has a lot of seepage of water inside it. So if it wasn’t maintained it would obviously flood.”

153 years ago though, the Tower Subway carried people rather than information.

It may look unbearably small today with its head-scrapingly low ceiling, but it was an engineering marvel of the day. Built-in 1869, it was the first underground railway tunnel to run under the Thames.

The Tower Subway
Credits: Alexander Viner
The Tower Subway

“Peter Barlow was a lecturer at the time, and he theorised about this new shielding system,” says Mr Arnold. “One of his pupils, called James Henry Greathead… tendered for the building of this [tunnel], and it cost about £16,000.

“He came up with this safety shield. So basically you put the shield up, they dug around it, then they put the cast iron grates around outside of it.”

The cramped 12-person carriage didn’t have a locomotive engine at the front but was instead pulled along a cable by steam engines at either end of the tunnel – more a primitive underground cable car than a train. 

Interior of the Tower Subway cable car, 1870
Credits: From the Illustrated London News in 1870, Public domain, via Wikimedia Commons
Interior of the Tower Subway cable car, 1870

This train was so unreliable that it closed after a few months and the tunnel was converted for use by pedestrians. But even this second life as a foot tunnel didn’t last long. While the Tower Subway charged toll fees, a new arrival just down-river – a little thing called the Tower Bridge – did not.

The Tower Subway was closed to the public in 1898 and converted to house hydraulic power lines. Following a near miss from a German bomb during the Second World War, it now serves the capital as a home for Vodafone’s telecommunication lines.

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