The Severn Railway Tunnel

Preparatory work

It was while working on the ferry piers for the Bristol and South Wales Union Railway in 1862–63 that Charles Richardson first began to pursue the idea of replacing the ferry with a railway tunnel beneath the estuary.  However, it took him three attempts, over a period of ten years, to get the plan accepted.  His first approach, in 1865, was rejected because the GWR were in the process of seeking an Act of Parliament for a project, proposed by John Fowler, for a new double track, mixed-gauge railway, 41 miles long, from Wootton Bassett to Chepstow, crossing the Severn at Oldbury Sands.  And by 1869, Richardson’s scheme also had competition from two other tunnel proposals.

Richardson’s estimate for his tunnel, and for the short lengths of railway at either end, was £730,000.  The tunnel’s chances of success improved dramatically when, in 1870, the newly elected chairman of GWR, Daniel, later Sir Daniel, Gooch, denounced the Fowler project as an extravagance.  Apparently he had come to realise that the director who had been pressing the case for this project at Board meetings, had been doing so to further his own interests.  After further lobbying, Richardson’s scheme was adopted by the GWR Company in 1871 and, the following year, the Severn Tunnel Bill was approved by parliament.  Construction began in 1873, with Richardson as Chief Engineer and with John (later Sir John) Hawkshaw as Consulting Engineer.

Plan showing the Severn Railway Tunnel

The construction of what would become the longest railway tunnel under water in the world at that time, turned out to be a classic example of an engineer’s extreme fight against adversity.  It is surely the leviathan of all Victorian railway tunnels and one of the nation’s finest engineering achievements.  An excellent and detailed account of the works is contained in the book written by Thomas Walker, the contractor who assumed responsibility for their completion after progress stalled in 1877. The description of events, given below, is based on information obtained from that book.

The bold attempt fails

The original intention was that the work should be undertaken by an experienced contractor but Richardson was not satisfied with any of the tenders he had received.  Hw was convinced that by using the GWR Company’s direct labour force he could complete the job for 25% less than would be the case if he accepted any one of the contractors’ bids and so he decided to go ahead on that basis.   However, four and a half years later, all he had achieved was one winding shaft and 1,600 ft of 7 ft by 7 ft heading under the river.  In August 1877, the Directors of GWR intervened and instructed that tenders should be invited for the remaining works.

Appointment of the contractor
Sir John Hawkshaw, 1877

Sir John Hawkshaw, 1877

Only three tenders were received in response to the new invitation and Hawkshaw, acting as consultant, recommended acceptance of the tender from Thomas Walker, an experienced contractor in whom he had full confidence.  However, the Directors took the view that Walker was asking too much for contingencies.  In order to minimise their exposure, should a disaster occur, they decided not to enter into a contract with him until the ground had been proved by the completion of the 7 ft x 7 ft heading right through the length of tunnel under the river.  In the meantime, the heading was to go ahead using direct labour.  Certain other relatively small items of work were also allowed to proceed, some by using smaller contractors, others by direct labour.

The first major incident

The pace of the work picked up significantly but, on 18 October 1879 when the headings that were approaching each other from either side of the river were only 138 yards apart, a great inrush of water occurred.  Within 24 hours, water had filled the works on the west side, up to the level of the tide.  Fortunately, the safety measures that had been put in place, enabled all the men working in the tunnel to escape with their lives.

There is little doubt that all the men who ran for their lives on that day were convinced that the river had broken into the tunnel.  However, when the initial shock had subsided and it became possible to rationalise events, it became clear that the point at which the water had broken in was not under the estuary itself but a short distance from the west bank.  We now know that the influx of water came from the “Great Spring”, a major aquifer that carries extremely pure water down from the Brecon Beacons and directly into the Estuary below low tide.  To day, over 130 years later, 20 million gallons of valuable spring water are still being pumped out of this aquifer, each day, from the point at which the tunnel had had been cut into it. At the time, this flow represented the daily intake of either Liverpool or Manchester – or about one sixth of the consumption of London.

Thomas Walker

The aftermath

The ingress of the Great Spring, no doubt, caused GWR Directors to ponder their previous statements about the amount requested by their chosen contractor for contingencies.  Their reaction, to all that had happened up to that point, was to invite Hawkshaw to take full charge of the works, as Chief Engineer, with authority to act as he thought fit.  Hawkshaw intimated that he was prepared to accept, but on condition that he be allowed to let the works to Thomas Walker.  The Directors concurred but still wanted the length of 7 ft by 7 ft heading to be completed under the deep channel known as “The Shoots” before any major works were undertaken elsewhere.  They asked Hawkshaw to seek a price for this element, alone.

Walker responded, suggesting that his 1877 tender should still stand, though modified to allow for the lapse of time and the amount of work still to be done.  He was prepared to concentrate on completing the heading under the river, as soon as he had dealt with the influx of water and pumped the workings dry.  This suggestion was agreed by all parties and the works were handed over to Walker on 18 December 1879.

Richardson’s Departure.

The events described above inevitably led to the departure of Charles Richardson from the project.  Great credit is due to him for the conception of the scheme and for its safe passage through the unpredictable Parliamentary procedures.  He also developed a system for successfully aligning the two headings with unprecedented accuracy.  However, while his administrative and conceptual expertise remained untarnished, his ability to drive a difficult project through to fruition had been called into question.  The extent to which his difficulties stemmed from a lack of expertise or commitment on the part of the GWR direct labour force is difficult to judge after the passage of so many years.  Before Richardson leaves the stage, it is worth mentioning that generations of boys, both young and old, should be grateful to him for coming up with the idea of inserting three layers of rubber into the cane handle of a cricket bat, a device that soon became universally adopted and is still used, worldwide.  It is on record that several of his professional colleagues, including Brunel, often complained about the amount of time that Richardson spent playing cricket!

The dramatic inundation of the works and the departure of Richardson provide a convenient point to leave the story of the tunnel. Another seven years would elapse before the tunnel was complete and ready to take its place as one of the outstanding feats of British engineering, a monument to the skill and perseverance of those involved. However, the prime purpose of this website is to provide information about the design and construction of the two motorway bridges and so it would be inappropriate to cover the whole of the amazing story of the tunnel in the main text. If you wish to read the rest of that story, click on the link below.

For completion of the tunnel, Click Here

The Conclusion

The incidents described above, and many other unexpected difficulties that bedevilled the operations, are all vividly described in Walker’s book, each one requiring men to work at the limit of human endurance and ability, while using the most advanced technology available at that time.  On several occasions, it seemed that the task would prove to be beyond the men responsible but, with outstanding skill and perseverance, they managed to overcome the obstacles and complete the task.

The first train journey through the tunnel took place on 5 September 1885.  A special coal train ran through from Aberdare to Southampton on 9 January 1886, but it was not until the end of 1886 that the tunnel was opened to regular traffic.  The construction of the 4 mile 628 yd long tunnel took almost fourteen years to complete.  The final cost was £1,806,248, two and a half times Richardson’s original estimate and nearly double Walker’s 1877 contract price.

The opening of the tunnel for regular passenger services on 1 December 1886 marked the end of Brunel’s unique steam ferry railway, the last crossing by the steam packet taking place the previous evening.  Over thirty years later, a ferry was re-introduced at New Passage, this time in order to transport cars and other road vehicles across the Estuary.  And later, with the inexorable growth in the car use after the Second World War, British Rail introduced an occasional piggy-back car-carrying service, through the tunnel.  Both these services ceased when the Severn Bridge opened on 8 September 1966.

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