Thursday, September 3, 2015

Before the Thames Tunnel: The Thames Archway

Marc Brunel's Thames Tunnel, the world's first underwater tunnel, was opened in 1843.  Originally designed to handle vehicles, it was only ever used as a passenger tunnel before it was bought out by the railways, but it was revolutionary, an engineering marvel, drawing a massive amount of tourist attention.  It was not, however, the first attempt to run a tunnel under the Thames, and an earlier attempt was also made from Rotherhithe.

Map of the proposed Thames Archway (from
the Grace's Guide website)
Innovator and engineer Ralph Dodd, probably best known for the Grand Surrey Canal, first proposed the creation of a tunnel beneath the Thames from Gravesend to Tilbury in 1798.  He managed to raise an Act of Parliament for the project in 1799 and was able to gain funding for it, but the project had to be abandoned in 1802 due to repeated water incursions during the construction of the shaft, which consumed half the finance raised for the construction of the tunnel before work on the tunnel itself had even begun.

The next proposal was made in 1802 by Cornish engineer Robert Vazie who believed that a tunnel link between Rotherhithe and Limehouse would be beneficial to both sides of the river. The expanding docks and the importance of communication between north and south of the river was putting increasing pressure on the government to supply a crossing. Accordingly, the Thames Archway Company was formed to run the project to create the tunnel.  Finance was raised and an Act of Parliament was passed in 1805 to enable the work to commence.  Vazie (c.1756-1822) was both a shareholder in and the chief engineer for the Thames Archway Company. 

Plan and esction of the proposed Thames Archway (from
the Grace's Guide website)
The plan sounded good on paper.  A narrow driftway would be established under the river, beginning in Rotherhithe, a little upriver from the Lavender Lock and the later Lavender Pump House (both of which survive today).  On completion it was to provide drainage for the main tunnel which would be built above it and would be lined with bricks to take both pedestrians and vehicles.  It would emerge at Limehouse at a point near to where the Regent's Canal Dock entered the Thames.  When it was complete it would be named the Thames Archway.

Apparently there was a ferry route very near to the site at the time that the plans were made.  It is mentioned in the  1880 edition of the Proceedings of the Institute of Civil Engineers (volume 60), but I haven't managed to get hold of it yet.  Ferry crossings will be the subject of a future post.

Work began in 1805.  A vertical shaft was sunk at the apex of Rotherhithe, near the end of Lavender Street.  It eventually reached c.70ft deep but there were great difficulties sinking the shaft due to the presence of quicksand and influxes of water.  When it was eventually completed, having eaten drastically into the tunnel's funding, a narrow driftway (or tunnel) was started.  The plan required a stable environment for the tunnel to pass through and this was the problem, because the geomorphology was neither firm or stable.  Not only was much of it sand and gravel, but there were pockets of quicksand as well.  Although the drifway was reduced in size from the original plan, the scheme again began to founder due to the invasion of water and the presence of the quicksand, which Vazie attributed to being provided with a pump with much lower capacity than he had requested.  

Richard Trevithick in 1816
by John Linnell.  Photo
sourced from Wikipedia
The Thames Archway Company's directors turned to other advisers and in August 1807  Richard Trevithick was hired, on the recommendation of Vazie, to work with Vazie.  His fee was to be a generous £1000.00 (equivalent to £32,170.00 today, according to the National Archives Currency Convertor), to be payable only on completion of the 1220ft tunnel, with £500.00 payable if the tunnel reached half its intended length.  Trevithick (1771-1833) was also from Cornwall and was both an engineer and an inventor, best known today for his work with steam engines and his Puffing Devil, a steam locomotive designed to run on roads, and the rail locomotive Catch Me Who Can, which was designed for an exhibition in 1808.  Although steam engines had been employed since early in the previous century, and were extensively used in coal mining, experimentation and innovation were still taking place and Trevithick was a master of applying steam under very high pressure to operate machinery.  He used steam to power heavy duty engines to pump water out of the narrow driftway. He also employed Cornish miners, who were experienced in tunnelling, to do the digging and employed other techniques learned from Cornish mining during the construction of the driftway.

By October 1807 394ft had been tunnelled, improving on Vazie's 6ft a day by tunnelling 11ft a day and this led, in spite of protests from Vazie's supporters, to the dismissal from Robert Vazie from the project.   All progress was attributed to Trevithick's involvement and the tunnel was now fully under his control.  Work proceeded and the driftway extended further under the Thames, passing the mid-way mark.  An unexpected layer of rock slowed proceedings as the miners were forced to chisel their way through to the soft ground on the other side.  On 23rd December 1807, when they broke through the rock, they ran into quicksand.  A breach formed in the roof of the tunnel and water started to pour in.   Remarkably, the miners held their position, repaired the hole with wood and continued push the tunnel forward.  However, in January 1808 another breach was more serious, and the tunnel flooded.  No-one died during the incident but Trevithick, who was the last to leave the tunnel, narrowly escaped drowning.  This time the breach was blocked with clay dropped onto the riverbed from above, and the tunnel was again pumped out.  By early February the tunnel was only 177ft away from Limehouse, but it was clear that to complete the project there would need to be a change of tactics.  Trevithick himself proposed that instead of continuing to work from inside the tunnel, work should continue from above, using coffer dams to block off sections into which sections of the tunnel could be dropped.  But the Thames Archway Company were not convinced and decided to bring in offer a £500.00 reward to provide a solution to the problem.  After 49 proposals had been rejected, the two independent judges decreed that a tunnel beneath the Thames was impracticable.  In 1809 the Thames Archway Company agreed that the tunnel could not be successfully completed and that a subterranean solution for transporting people and vehicles was simply not possible.  With only 200ft left to go, and 1000ft already completed, the project was terminated, and the Thames Archway Company was dissolved later in the same year.

Whether or not the tunnel could have been completed is uncertain, but Trevithick's own solution to the problem was later used successfully for the Bay Area rapid Transit Tunnel project in San Francisco.  

It was not for another 34 years that the Brunels' Thames Tunnel proved that with the right minds and the right technology, a Thames tunnel was feasible.  Although the Brunel tunnel also started in Rotherhithe, it was half a mile upriver from the Thames Archway driftway, and took a different trajectory.

There is no sign today of the driftway or its shaft.  The original site of the shaft, upriver from Lavender Lock, must lie under the Sovereign View housing development, as does a lot of that stretch of Rotherhithe's former river-front heritage.  

Principal sources for this post:
The Brunels' Tunnel. The Brunel Museum 2006


1 comment:

bernard said...

Thank you . . .