The Clifton Zip Wire

Imagine a zip wire running through the Avon Gorge, under the Clifton Suspension Bridge, depositing a flock of happy flying punters on the Bedminster side of the river.

You may not have to imagine for much longer, for such a plan has already been proposed and supported by Bristol’s tourist authorities.

When this idea was first mooted in the Bristol Post recently, one of the questions posed was, “What would Brunel think?”

To contemplate his potential response, I’d recommend considering Brunel’s involvement in the 19th Century equivalent; his daring crossing of the gorge in a basket suspended beneath an iron bar that had been hauled the 900 yards across the gorge in the days before the laying of the foundation stone of the bridge in 1837. It’s an event that we marked in our Rag Morris Mummers Play, “The Nine Lives of Isambard Kingdom Brunel”, first performed in on Bristol Doors Open Day, September 12th 2009 to commemorate the 150th anniversary of the death of the great engineer.

Excerpt #10 - The Clifton Bridge

To expand on our 90 seconds worth of exposition about the bridge from our half hour play, and to mark 5 years since that play first saw the light of day, 150 years since the Clifton Suspension Bridge was opened, and 155 years to the day since the death of Brunel, I thought it was time to write a bit more about how the bridge came to be built; about Brunel’s crossing on the Iron Bar and while I’m here, suggest a few things that the Clifton Zipsters might wish to look out for on their way back up to St Vincent’s Rock. I’ll admit that the page title is a bit misleading; but imagine, before the bridge was built, that the idea of crossing from one side of the gorge to the other by any means must have seemed as spectacular and as thrilling as today’s plans to install a zip wire.

The challenge is this! There’s a new competition…

Brunel’s design for the bridge was a response to a competition launched to find a solution to a problem – building a bridge across the Avon downstream from Bristol Bridge that would be high enough for tall ships to pass underneath, in a time before swing bridges and lift bridges were commonplace. The cliff faces of the Avon Gorge between Clifton and Leigh woods provided a natural foundation for the bridge. This was the site that an Alderman of Bristol, William Vick, had specified in 1753 when he left a legacy in his will that was intended to be used to build a Clifton Crossing, once the sum had accumulated to £10,000. By 1829 the Bridge Committee felt that sufficient funds were available and news of the competition caught the eye of one Isambard Kingdom Brunel, the 20 year old son of Sophia Kingdom and French Engineer Marc Isambard Brunel.

At that stage, the young IKB had been working as a resident engineer on his father’s Great Project – building a tunnel beneath the Thames between Rotherhithe and Wapping; the first underwater passenger tunnel ever attempted. However this dangerous work had resulted in a terrible flood on 12 January 1828, which left six men dead, Isambard severely injured, and work on the flooded tunnel suspended. It took six months for him to recuperate, time he spent in London, Plymouth and Bristol. While he was in the West Country he began to make the connections which would lead to him working in the Bristol Docks and submitting four proposals in response to the competition for designs for a Clifton Suspension Bridge. Each design crossed the Avon Gorge at a slightly different point, with spans of between 720 and 916 feet; two of which suspended the chains from the rock faces rather than from masonry towers.

Brunel's Plan No.3

Brunel’s Clifton Bridge – Drawing No.3 (University of Bristol / Brunel 200)

The Bridge Committee appointed Thomas Telford, then the first President of the Institute of Civil Engineers, to judge the competition, bringing IKB into direct contact with one of the pillars of the engineering establishment. While Brunel’s proposals were imaginative and well received, when it came to actually building the bridge, Telford rejected all twenty two of the proposals submitted to the competition, including Brunel’s. Telford declared that the intended spans, dictated by the topology of the landscape, would be too wide for any suspension bridge proposed, due to the problem of lateral resistance to wind pressure. Telford’s own estimate of 600 feet as being the upper limit of the cast iron technology of the time, was remarkably similar to the span of his own Menai Suspension Bridge, completed in 1826. Instead Telford was asked to submit his own design, which reduced the span by the required distance by building a pair of massive stone pillars from the base of the Avon Gorge.

Telford Clifton Suspension Bridge plan full

Telford Clifton Suspension Bridge plan – (Wikimedia)

Brunel’s response was cutting:

As the distance between the opposite rocks was considerably less than that which had always been considered as within the limits to which Suspension Bridges might be carried, the idea of going to the bottom of such a valley for the purpose of raising at great expense two intermediate supporters hardly occurred to me.

Such a response was in fact slightly disingenuous, as Marc Brunel had previously suggested to young Isambard that the gorge “could not be crossed in one” and had sent a sketch showing a single intermediate supporter raised from the bottom of the valley – which appears to divert the course of the navigable river Avon to one side to accommodate it.

But why was Marc Brunel attempting to influence his young prodigy in the first place? In fact, it’s well documented that Marc Brunel was far more involved with the Clifton Bridge design than he is often given credit for. His sketch of a bridge with a support going to the bottom of the Avon Gorge was remarkably similar to one of a pair of suspension bridges at in the French island of Réunion, now known as Saint Denis, east of Madagascar, that had been designed and built by Marc Brunel in 1823; six years before the Clifton Bridge competition opened. The bridge over the Riviere du Mat also has an intermediate supporter in the centre of the bridge; compare for instance the arc of the additional suspension chains below the deck of the bridge, which were intended to give the bridge additional stability, and were a novel part of Marc’s design. Isambard, who supervised the assembly and testing of these bridges in England before they were shipped out to the Indian Ocean in kit form, also incorporated such inverted chains beneath the structures of all four of his original proposals.

Suspension Bridge on the Isle of Bourbon (Collection of David Denenberg)

Suspension Bridge on the Isle of Bourbon (Collection of David Denenberg)

Once Telford’s expensive solution was also rejected, in October 1830 the Clifton Bridge trustees reopened the competition for the bridge design, and Brunel, who had been continuously modifying and improving his own designs, was in a position to resubmit an application and was invited to do so, along with twelve other engineers. Following further consideration, Brunel and Telford were on the short-list of five; although Telford’s design still included the two “intermediate supporters” and was subsequently rejected.

Surprisingly, perhaps; one of Brunel’s four entries to the second competition also made use of a pair of massive pillars reaching down to the level of the river. Given Brunel’s earlier disparaging remarks, one wonders whether this was out of sheer pragmatism. If the judges might eventually decide that this was to be the principal that they wanted the design to follow, then Brunel was going to make sure that his proposal was the best of the bunch.

Brunel, he did enter – and won!

The four remaining engineers were allowed to continue working on their designs and Marc Brunel’s diary for early 1831 includes several months of work on the Clifton Bridge. When the final proposals were submitted, Isambard’s design was placed second; but he arranged an audience with the judges at Blaise Castle and through his not inconsiderable powers of persuasion, was able to resubmit his designs to address the engineering deficiencies that the judges had considered; an opportunity not afforded to the three other engineers. Isambard Kingdom Brunel was appointed as engineer to the Clifton Suspension Bridge on the 19th of March 1831, less than a month before his 25th birthday.

Even then, until the end of June, Marc Brunel was still busy working on the designs for Isambard’s bridge; and yet he was happy for the work to be credited to his son; perhaps for reasons of paternal altruism. Isambard’s appointment was made with the full knowledge that his more experienced father was known to be working on the designs; there was a safe pair of hands behind the inexperienced, yet talented, young engineer.

It could be said that Isambard Kingdom Brunel was Marc Brunel’s greatest engineering legacy; and that 150 years later, perhaps Isambard Kingdom Brunel as an individual or “brand” is greater than the sum of his engineering achievements. There are certainly other engineers whose works were more profitable, more numerous and more successful from an engineering point of view but the legacy of Isambard the Great Engineer, innovator, self publicist and showman has given his diminutive stature a longer shadow that many of his contemporaries.

To prove it would work, he traversed the route early

Before the foundation stone was laid amid pomp and ceremony on Saturday 27 August 1836 it was decided that the best way of transferring building materials from one side of the gorge to the other would be to install an iron bar across the gorge with a system for winching stuff across in a basket. The bar was 1000 feet long and 1½ inches wide and was welded together on the Leigh Woods side. Once it was assembled, on 23 August a ship’s mooring rope or hawser was passed across the gorge and the bar was carefully pulled across by winding this rope up with a capstan. However, just as it was about to be fixed to the rocks on the Clifton side, the hawser broke and the bar fell into the Avon Gorge. When the bar was hauled back up again the bar it somewhat the worse for wear.

This incident is beautifully described in “The Literary Gazette, and Journal of the Belles Lettres, Arts, Sciences, &c” 1836 edition. The British Association held their Sixth meeting in Bristol in August 1836 and it is no coincidence that Brunel chose to organise the ceremony of the laying of the foundation stone when some of the greatest natural philosophers of the day happened to be in town. In consequence, some of the events surrounding the ceremony have been recorded in this fascinating document.

In the course of the forenoon the iron rod, stretched across the Avon for the ceremony of Saturday morning, when the first stone of the suspension bridge is to be laid, was precipitated from its airy height in consequence of the breaking of a rope on the Clifton shore. One man only was slightly hurt, but the iron was embedded above five feet deep in the bed of the river. Its appearance, when fished up again, was very curious, being not only crusted with mud, but bent into all the forms of the channel into which it had been precipitated. Its curves and contortions, when once more elevated to its position, which was ably accomplished by the engineer (Brunel junior) before Thursday morning made it a more picturesque object than it was before; and thousands visited the spot which had become additionally interesting from the accident.

The breaking of the iron rod over the Avon created a strong sensation; and Mr Brunel approved himself worthy of his parentage, by the skill and exertion with which he fished it up and replaced it in time for the ceremony of Saturday morning.

The 27th August saw the grand ceremony for the laying of the foundation stone which was followed by a breakfast at the Gloucester Hotel, at which “The reception of the elder Brunel who arrived during the repast must have been particularly grateful to his feelings”. This was followed by a somewhat more notorious incident:

On the evening of this day, Messrs Laxton and Tait, two young engineers, we believe employed on the bridge, got into a basket-car and were drawn across the rod. Some obstacle occurred about midway, and the rope by which they were being pulled across, was obliged be loosened; and this at a time when the Benledi steamer was passing below. Her mast caught the line and had it not been cut with great presence of mind, in all probability a fatal catastrophe would have attended this adventurous attempt. As it was the oscillation of the rod with the suspended car was appalling, and the terror of the spectators was scarcely appeased when they saw the parties drawn back in safety to the shore.

It is curious that any suggestion of Brunel himself having a similar accident is not reported in this journal. The Bristol Mirror newspaper, however, reported the above story with some slightly different details; the basket contained one man, and named the Killarney as being the steamer involved. It then went on to say that that Brunel had a similar incident later in the same day where the basket stuck fast on the “kink” of the bar; whereupon

Mr Brunel endeavoured by swinging it to and fro to release the car but being unable to do so, this intrepid gentleman mounted the car, climbed the ropes and released the car when swinging over this tremendous chasm.

A. Vaughan in his excellent biography of Brunel, “Engineering Knight Errant” suggests that the above story may well be hearsay and somewhat unreliable. Perhaps the Bristol Mirror’s story pertaining to Brunel was a fabrication based on the event related above. In any case, it may well have been the start of the separation of the fact and the fiction in the history of Brunel; adding a dash of heroic mythology to the story of the Great Engineer.

It is better documented that the bar was replaced during September and on the 27th of that month Brunel travelled in the basket across the gorge “with the greatest of ease”, three times; on each occasion with a different companion. Many years later in 1854, according to L.T. C. Rolt’s biography of Brunel, when work on the Bridge had ceased due to funding problems, the trustees collected £125 from people wishing to cross the gorge in a basket themselves. Rolt also suggests that the anchorage points for the bar are still visible near the bases of the abutments on both sides of the gorge. In fact, on the Leigh Woods side, the anchorage point is a square pillar that can be seen on the south side of the bridge approach. On the Clifton Side, the anchorage point is no longer visible but is marked by a pair of trees.

On 26 December 1835, the 29 year old Brunel wrote in his diary an end-of-year summary of his ongoing works, mostly railway-related, but including the famous quote:

Clifton Bridge – my first child, my darling, is actually going on – recommenced last Monday – Glorious!

And also a remark about his other suspension Bridge.

Suspension Bridge across the Thames (Hungerford foot-bridge) I have condescended to be engineer of this but I shan’t give myself too much trouble about it. If done it will add to my stock of irons.

However, his optimism was short-lived. The Hungerford bridge at Charing Cross would turn out the be the only suspension bridge to his design that he would live to see completed.

Incomplete in his lifetime

As with many of Brunel’s projects, the Clifton Bridge was not immune to financial considerations. The budget set aside for the bridge was never enough to complete it and despite efforts at additional fundraising the project stalled soon after 1840.The abutments, piers and towers on both sides of the bridge were mostly completed but bridge itself remained unbuilt and the suspension chains, although delivered by the Copperhouse foundry of Hayle, were surplus to requirements. The abutments became a popular venue for picnics and other, perhaps less wholesome, activities, and there was some discussion about whether to remove the unfinished construction work to return the gorge to its natural state.

With the bridge works on the back burner, over the course of his career Brunel was busy with a hundred other projects; including the Great Western Railway and various branch lines as well as railways in Ireland, Italy and India; his three Great Steamships; supervising the design and construction of the Great Exhibition and designing a portable field hospital used during the Crimean War.

In one of these projects he returned to the Avon Gorge with a proposal to build a railway down the western bank. The Portbury Pier and Railway company obtained parliamentary permission to build a railway line in 1846 to lead to a floating pier at Portbury; an early attempt to encourage shipping away from Bristol docks, which had the disadvantage of being situated some miles up the winding, tidal river Avon. As engineer to this company, Brunel proposed that the railway should use the Atmospheric Principal. At this point Brunel’s atmospheric railway in South Devon was under construction but not quite operational. If the Portbury line had been completed as planned, it may well have been a useful, less high profile, testing ground for this innovative system – which in South Devon generated the fastest speeds of any railway yet built. In the end, however, the atmospheric railway failed due to various technical and financial challenges, including problems with frost and rats; and Brunel’s Portbury line was shelved when the fundraising failed. A new company was formed some years later to build a railway to Portbury and Portishead, which received parliamentary approval in June 1863 and opened less than four years later in April 1867. Note that the current plan to rebuild the railway to Portishead always involves a perpetual five year wait.

Brunel’s final great bridge – the Royal Albert Bridge that carries the Great Western Railway across the Tamar from Plymouth to Saltash, was an extravagant yet elegant and uncharacteristically economically viable engineering solution to the problem of crossing the waterway. The design of the bridge includes two vast spans formed of lenticular, or lens-shaped trusses; the tops of the trusses being formed from heavy iron tube, the bottom of the trusses formed from a pair of chains. For these, Brunel bought the unused chains from the Clifton Bridge Trustees and had some more links made up at the Copperhouse foundry.

At the time that the bridge was opened in April 1859 by Prince Albert, Brunel was returning from a trip to Egypt where he had hoped the atmosphere would be beneficial to his health. The following month he was taken to see the Tamar bridge but by this time his health was so poor that he had to lie down on a couch while a locomotive pulled his carriage slowly across. Years of smoking, working long hours and suffering from accidents of various kinds were taking their toll.

A few months later, as his leviathan steamship, the SS Great Eastern, designed by Brunel and built by John Scott Russell, was being prepared for her maiden voyage, Brunel suffered from a heart attack on board and was taken back to his London residence to recuperate. He never recovered and died of a stroke on 15th September 1859.

Finished by friends, as a fitting tribute

Following his death, there was a posthumous proposal to complete Brunel’s vision for a Clifton Suspension Bridge as a memorial to the engineer. Foremost among those in favour of this scheme was John Hawkshaw; a leading light in the Institute of Civil Engineers, and distinguished engineer William Henry Barlow, who who were to become engineers to a new Clifton Suspension Bridge Company, with many other leading engineers acting as trustees. Hawkshaw was at that time planning the construction of a new London station at Charing Cross to be reached by a railway bridge across the Thames. This work would involve the dismantling of the Hungerford Bridge that Brunel himself had designed; and Hawkshaw realised that the new Clifton Bridge Company could be sold the suspension chains from that bridge while maximising the scrap value for the London Bridge and Charing Cross Railway.

The bridge company quickly found that financial support was forthcoming to find approximately £35,000 for the completion of the bridge. There was some concern among former bridge trustees and some Bristolians that the project was being managed and funded by Londoners, but a compromise was reached. A parliamentary “Act for erecting a Suspension Bridge from Clifton in the City and County of Bristol to the Parish of Long Ashton in the County of Somerset” became law on the 28th June 1861. Hawkshaw and Barlow re-engineered the design for the bridge to bring it up-to-date with current engineering principles, and also reduce costs by removing some of Brunel’s embellishments. The height of the piers was increased from 230 feet to 245 feet above the level of the river; the bridge deck was reduced from 32 feet to 30 feet in width. In many ways it is a bridge that is sited at Brunel’s original site and has a similar outline to the bridge that the Brunels – both Marc and Isambard – designed but on closer inspection holds few of the details that I.K.B himself may have planned to include.

The bridge was opened to foot passengers on 9th December 1864 with all the pomp and ceremony that Brunel himself would have appreciated; and there were beer and sandwiches at the Victoria Rooms for the workers. Conspicuous by their absence from any of these celebrations were I. K. Brunel’s sons; Isambard and Henry, who felt that not enough had been done to recognise the part their father had played in the project. They considered that Hawkshaw and Barlow had taken all the credit; despite the whole enterprise being a memorial to their esteemed father.

In future years both John Hawkshaw and Henry Marc Brunel would leave their legacy on the River Thames in ambitious projects that both Isambard and Marc Brunel would have been proud of. Hawkshaw was engineer to the East London Railway Company, which in 1865 took over Marc Brunel’s Rotherhithe to Wapping foot passenger tunnel, eventually using it to carry a railway line from New Cross to Shoreditch; now part of the London Overground network. If you’re in the area, do visit the splendid Brunel Museum at Rotherhithe. And Henry Marc Brunel, who learned engineering skills as a pupil of Hawkshaw became structural engineer to another Hawkshaw pupil, John Wolfe Barry, when he was chief engineer of Tower Bridge in London; which, like the Clifton Suspension Bridge, was an elegant 19th Century solution to the problem of designing the furthest downstream bridge on a major waterway that would allow tall ships to pass underneath.

The Clifton Zip Wire

The idea of a zip wire from the Clifton Bridge to Bedminster creates a bit of a problem – where would the wire end up? I would expect to be given the same constraints that Brunel was under, to allow safe passage for a tall ship to travel under the wire – with clearance of around 30 metres at the exit from the Cumberland basin, around 600 metres away from the bridge.  Starting at the Clifton Observatory at around 90 metres above the high water mark, the zip wire would need to be at least 900 metres long, by my rough reckoning. To avoid the “Brunel Way” flyover, the wire would have to end up in Greville Smyth Park, or possibly on some corner of the Bedminster Cricket club. And I’m not sure if they’ve been asked yet.

So, what would the little blue daredevils have to look at on their long walk back to Clifton? I present three quite interesting structures of architectural and engineering merit that could be investigated.

1) The Ashton Avenue Bridge

The Ashton Avenue Bridge

The Ashton Avenue Bridge (Photo: Gavin Skinner)

This was once a swing bridge at the entrance to the New Cut, which carried the Bristol harbour railway on the lower deck and road traffic on the upper deck. Long since replaced by the Brunel Way flyover, the upper deck has been removed and the lower deck is a footpath and cycleway now used as part of the national cycle network.

Plans are afoot to incorporate the bridge in the controversial Bristol MetroBus system. According to TravelWest, the plan is to “restore the Victorian Bridge and return it to its original role as a public transport corridor.”

I for one would love to see it restored to its Victorian double decker heyday with a separate roadway for the buses and cycleway underneath; it would be particularly impressive to see it in operation as a swing bridge again; although I don’t suppose this is what the MetroBus People have in mind.

2) Brunel’s Other Bridge

Brunel's Other Bridge

Brunel’s Other Bridge (Photo: Gavin Skinner)

This structure, currently hidden away beneath the larger Plimsoll Bridge at the end of Cumberland basin (which leads on to Brunel Way) was a large wrought iron swivel bridge, which was designed by I.K.Brunel’s engineering practice and first became operational in 1849. Its iron tubular structure can be seen to foreshadow Brunel’s later railway bridge over the River Wye at Chepstow and the Prince Albert Bridge over the Tamar. Before the Clifton Bridge was completed, Brunel finally achieved his ambition of constructing the first bridge over the Avon upstream of the Severn estuary.

There’s a campaign by various local enthusiasts to restore and preserve this bridge for future generations, and they are doing a fantastic job.

3) The Clifton Rocks Railway

The Clifton Rocks Railway - Lower Station

The Clifton Rocks Railway – Lower Station (Photo : Gavin Skinner)

This uneconomical funicular railway was built in a tunnel through the cliffs from the Avon Gorge Hotel, to Hotwells, first opened in 1893. The intention at the time was to offer connections from Clifton Village to the tramways into the city centre, the railway to Severn beach and steam ships from the Hotwells landing stage. After the widening of the Portway in 1922 – now the main A4 route between Bristol and Avonmouth – the Clifton Rocks Railway fell into decline and closed in 1934; although it was used by the BBC as a radio broadcasting studio during the second world war.

I would propose that the most exciting route back for out intrepid Clifton Zipsters would be up through the Clifton Rocks Railway tunnel. I know that it’s never going to be reopened as a railway but perhaps some kind of pulley system could be reintroduced?

In conclusion

I hope this has been a useful potted history of the Clifton Bridge; and the interconnected roles played by Marc and Isambard Brunel, John Hawkshaw and William Barlow; and how it fits into the surrounding natural and historical landscape. I look forward to taking my place in the queue for the the Clifton Zip Wire, whenever it gets built; or if not, alternatively I can hope that one day I shall have an opportunity of crossing the gorge in a small basket, suspended beneath a thin iron bar.

References

Bristol Post (2014) 70mph zip wire planned for Avon Gorge in Bristol
Rolt, L. T. C. (1957) Isambard Kingdom Brunel
Vaughan, A (1991) Isambard Kingdom Brunel : Engineering Knight Errant
Clements, P (1970) Marc Isambard Brunel
Portman, D (2000) The Clifton Suspension Bridge : A Business Enterprise
Various (1836) Literary Gazette and Journal of Belles Lettres (Volume 20) pp 553, 567, 568
Bristol 24-7 (2010) Brunel rejected father’s pagoda plan for Clifton Suspension Bridge
Brunel 200

Wikipedia Portishead Railway
Bridgemeister 1826 Réunion Suspension Bridge
TravelWest The Ashton Avenue Bridge
The Clifton Rocks Railway
Brunel’s Other Bridge
The Clifton Suspension Bridge

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