Memoirs of a Railway Volunteer - Part 2

Adventures in Railway Design – Part II. The Bridging Campaign

If you get involved in railway bridging projects then you will soon come up against the following facts of life: fatigue life, stress calculations, grandfather rights, corrosion, drawings, abutments, structural engineers and their professional insurance.

HMRI require any railway bridge being put into service to have an estimated fatigue life of 140 years, based on stress calculations carried out by a qualified structural engineer and covered by his insurance policy. For this purpose the engineer will need the structural drawings to which the bridge was built, and these are no use if the bridge is subject to significant corrosion or other damage. No drawings, no bridge.

Where a railway bridge is already in use then you can generally continue to use it without carrying out a stress analysis to modern standards. This is the “Grandfather Rights” rule. If you move a bridge, or bring a disused one back into use, then you have to comply with the modern rules.

Finally, if you are building a bridge from scratch, I am told that 90% of the cost is in the abutment, so a second hand deck is usually only a marginal saving.

Bridges are normally built from two girders which are transported separately and bolted together on site. If you want to dismantle one you either shut the road for several days or find a way to take down and transport the structure in one piece, for which it was probably never designed.

Once in a while somebody comes up with the bright idea of buying a second hand bridge deck for Peak Rail “to span the A6 at Rowsley”, the bridge on the old TI goods branch over the ring road at Chesterfield is usually the favourite. Granted it is relatively modern, unless there are proper plans, and unless there is a proper bridge engineer in charge, you can forget it. The transport costs would probably be of the order of £10,000, and the odds on actually being able to use the bridge if it was recovered are currently unquantifiable.

Incidentally a plan was drawn up by an engineer called Roy Hughes in the mid eighties, which called for a skew span with girders 94 feet long. The bridge is on a bend in the highway and a safe line of sight must be prepared. I’m pretty sure the Chesterfield span is too short.

Fortunately, when it came to rebuilding the bridges from Darley Dale to Matlock, we had a very experienced bridge engineer and his name was Bill Stubbs, who sadly died in about 1990. Bill was theoretically retired, but still working as a consultant and as active as a mountain goat. Also to the point, he was insured. Like most professional engineers he wanted things just so, and his word was law. Bill had been active in supporting the railway in the very early days, but got put off by what he saw as the amateurish shenanigans of the Board in the early 1980’s. I had considerable sympathy for this. Around that time I was chairman of the Mansfield branch. We had raised £2000 and the PRS board simply could not tell us what we should spend it on to help them most. The Buxton volunteers virtually had to declare UDI to get anything done.

Among Bill’s early work for the Railway was the preparation of a feasibility study, one of a number commissioned in support of the project. I read them all as part of the preparations for Darley Dale, and frankly some of them made me feel quite ill to think we had commissioned such reports, by allegedly qualified persons. I was left with a deep scepticism about almost all consultants, abundantly justified by later experience.

Bill’s study was very different, here was a report by someone who had a sound grasp of engineering, who actually did it rather than just writing about it, and who understood what volunteers could do when organised in teams under qualified leaders and properly equipped. I got in touch with him and managed to persuade him that Peak Rail now meant business.

Bill acted as our unpaid consultant and began design work on the bridges on the old trackbed. The biggest problem was Bridge 35, with Bridge 40 a close second.

The bridge numbers run from Ambergate Junction. Bridge 35 is the iron bridge at Matlock, and is bigger than you might think. It has four wrought iron spans on a curve to a total of 270 feet. Bridges 36, 37 and 38 were all 10ft span cattle creep or flood drainage bridges, of which 36 was in the best condition and had been rebuilt at some point. Bridge 39 is the skew arch road overbridge at Darley Dale and Bridge 40 is the 10ft span over the Warney Brook, immediately to the North of Bridge 39 and at the bottom of Darley Dale South Yard.

Bill immediately condemned Bridges 37,38, and 40. These consisted of timber way beams in steel troughs which had corroded to the point where Bill could not calculate the strength any more. Bridge 39 had no problems, and is well worth careful study if such things interest you. The masons marks can still be seen carved in the stones of the skew arch – they were paid piecework so each man’s work had to be identifiable. Bridge 36 had a sound corrugated steel deck, and could be strengthened by laying reinforced concrete on the top. Bridge 40 was propped up with timbers and temporarily brought into use for works trains.

Bridge 35 was the mischief. Analysis showed it was made of wrought iron, which is not as liable to corrosion as steel, but which is difficult to arc weld reliably. The bridge consists of two side girders connected by cross beams and covered in wrought iron plates. A modern version of this bridge would have a third girder down the middle. This gave it a lack of some vertical strength, and a greater lack of lateral strength, i.e. ability to resist a derailment heading for the river. The safety factors required are, rightly, very high. However, if the bridge had been stronger then Tarmac would undoubtedly have used it to gain access to their quarry nearby, with dire consequences for ourselves. At one very early point the PRS was trying to persuade the interested parties to agree to a longitudinal level crossing, and I can just imagine what HMRI would have made of that.

One proposal to strengthen the deck involved welding all the edges of all the deck plates together. Bill disposed of this by pointing out that once the plates were covered in ballast and the track had been relaid, it would be impossible to monitor the condition of the welds. I remember him saying that whereas once upon a time he could have proved the deck with four pages of calculations, now it would take over forty. His specification for the work included, breaking out all the concrete haunches along the edge of the deck, so that the girders could be fully inspected, and drilling large numbers of holes in the deck for weep holes, into which short lengths of water pipe could be welded so that the drips went straight into the river instead of running back under the plates and causing corrosion. The upper surface of the deck had to be cleaned and painted with epoxy paint, and a number of corroded cross girders replaced at the Matlock end of the bridge. We promised him we would paint it before too long. This would require a huge scaffolding and sheeting to prevent any old paint (possibly lead based) from going in the river.

The design of Bridge 40 also gave problems. Severn Trent objected to Bill’s standard concrete deck on the ground that it might give insufficient flood clearance for the Warney Brook. I pointed out that immediately downstream was a small culvert under the road which would undoubtedly restrict the flow, but they were unmoved. Unless we carried out our own hydrological survey, of the rain gathering properties of the hills above Darley Dale, we would have to do it their way. One day the culvert might be rebuilt, and then where would they be if we had a restrictive bridge?

The tricky bit is that the trains have to go under Bridge 39 immediately south of Bridge 40, so there is a limit to how high the track can be raised. Bill dealt with this by providing a neat steel trough girder design in which the main strength is alongside the rail, thus saving a crucial amount of height. There is a “limit of lift” plate under Bridge 39, which I bought at an auction, but whether it was accurately set, or just put up to look pretty I cannot now recall.

Meanwhile, elsewhere, the optimists had been at work. Quite independently of Bill, projects were hatched to obtain various second hand decks for use on nebulous projects, mostly North of Rowsley, where we had no access to the trackbed. The first to arrive were some bridge girders from a site in, I think, St Helens. The idea was that they would look very impressive and would show that we had some prospect of bridging the gaps on the way to Bakewell. Have a look at some of the editorials in “Steam In The Peak” in the late 1980’s. Forgive me, I was very naïve about bridges in those days and went along with this. The girders had got just a tiny bit mangled in the demolition process, and while the optimists said they could be repaired, Bill was coldly realistic. At least we got a reasonable amount for the scrap. A little later we also received an old and rather peculiar footbridge made of tubular steel. The optimist who organised this was adamant that it could be used as a footbridge over the railway at Darley Dale, and it was being given away “free”. Except for the transport cost of course.

When the footbridge arrived it was abundantly clear why it was being given away. Once the concrete deck panels had been prised off, the main girders were severely corroded. As I recall that optimist was conspicuously absent when this work was being done. The deck panels were used as paving slabs, and the main tubular members were eventually used to make conduits under Station Road for the level crossing. The rest went for scrap, I suppose it did not cost us very much in the end.

The crowning effort of the bridge optimists was the attempt to obtain a series of bridge decks from Hull, one of which would have been big enough to span the A6, allegedly. They had a report from a well regarded engineer, but not I think a bridge engineer, to support their case. Delivery of the shorter deck was arranged in the general euphoria which surrounded the share issue before the financial crisis of 1989 hit the railway. The far, far more expensive delivery of the longer deck was cancelled, not without bitter opposition in certain quarters. I am quite certain the second deck would have bankrupted the company. As it was we had blown away about £10,000.

Bill got to hear about the deck arriving, and was displeased. Where were the drawings and the calculations? Was I aware that the cost of the deck was only ten percent of the value of a bridge contract? I was now. Bill was there when the deck arrived at the industrial estate at Rowsley. Holes had been cut with oxy acetylene gear in the main plate girders so that the lifting chains could be attached. Even I knew that the heat changes the properties of the plate around the hole. Bill glared ferociously at the holes. Normally polite and well spoken, all he said was, “well that’s &*@$ed that”, as he turned on his heel and walked away. It turned out that the optimists had not consulted Bill at all and there was no adequate reason for this.

The basic problem was that many of the directors were fully occupied running their own departments, and did not have enough time to look at the company strategy as a whole. This is the difference between managing and directing. What we did not have were non-executive directors, who should have wide experience and no specific responsibilities. Their job is to ask nasty questions and make sure the basic company assumptions are soundly based. In hindsight it was painfully easy for one or two mavericks to go off on a tangent of their own.

Once the first slice of Buxton had been sold, at the end of January 1990, the financial crisis was over, and things were put on a very different footing. Mick Thomas rallied the volunteers, and from that point nothing happened which was not directly relevant to the drive on Matlock. Sadly Bill died before the bridge works could be completed, and Dick Smith was appointed as a replacement.

The easiest bridge to tackle was bridge 36, which had been dealt with by volunteers during the late summer of 1989, and I seem to remember that Mike Hancox took a leading role there. It involved an enormous amount of work which is now easy to take for granted – re-pointing the masonry, needle gunning the deck and laying a large amount of reinforced concrete, not to mention clearing a lot of mature hawthorn trees before work could start.

Mick now planned to attack bridges 37, 38 and 40 simultaneously and in short order. He brutally squashed an optimistic attempt to lay a double track deck on bridge 40, proposed on the grounds that “one day it might come in handy”. Tenders were issued, and contractors engaged. By mid April 1990 bridges 37 and 38 were being shuttered for concreting, and both were complete by the first week in May.

Meanwhile, the episode known as “The Battle of Bridge 40” was in full swing. As soon as the winter floods were over, in mid-April the channel below the bridge, and the culvert under the road, together with a long stretch downstream, were dug out to ensure a low water level


The track across the bridge was lifted and the old deck removed. The stream was dammed off, and the abutments taken down to foundation level and rebuilt. By the end of June the temporary deck was back in place, and works trains were running South again. Mick was also leading the salvage operations at Stantondale. The new deck was delivered and in place by 7th July, though only fit for works trains at that point.

The absolute priority was now to connect the railway to the exchange siding at Matlock, and to rescue the coaches there. Starting from a point 500ft North of Bridge 38, the connection was made on 16th December, with temporary track laid over bridge 35. The optimists had left us one last surprise, which was that the bridge centre lines at Bridges 37 and 38 had been skewed as far as possible towards the A6, so that if their cherished dream of a double track railway ever came off, there would be room for both lines of railway and a public footpath. This was all very well, but when the track was lifted to level, it was very clear that it was right on the edge of the embankment, which has had to be discreetly widened in places.

Bridge 35 came a little later, and my notes are almost non-existent, as I was up to my ears in salvage work at Hams Hall. My recollection is that it was actually the largest and most expensive of the bridge contracts, particularly in respect of the new steelwork under the South end. Despite our previous battles, Tarmac were big enough to allow access through the quarry for our contractors.

Despite all the expense and all Bill’s expertise, bridge 35 could only be passed for axle loads up to 19 tons. It would take a Black 5, for example, but not a Jubilee, certainly not Flying Scotsman, and this remained a particular frustration. Various engineers were called in to advise. I remember one expressed surprise that the track was now in the middle, and not on one side or another as originally designed. He went off to do his calculations, and came back months later, saying he now thought Bill was correct. The problem is that the bridge as a whole is weak, so there is no one component which will magically strengthen it if improved, with the possible exception of extra piers in the river. The river authority are highly unlikely to permit this. One BR engineer swore he could fix it easily but it turned out that he did not have the insurance to cover the job. We had a quote from our consulting engineers of £12,000 just for giving it a preliminary study, not actually designing a solution and certainly not doing any work. It remains an enigma, and one day we really must paint it.

Tim