HomeInfrastructureThe ties that bind

The ties that bind

The viaduct’s 108 pattress plates
have been prepared and repainted, whilst 46 drainage hoppers have been replaced. ©FourByThree

As we glide in 21st-century comfort along continuous welded rail – connected to social media and six billion web pages – it’s easy to forget that much of the infrastructure we’re travelling on, through or over is a product of Victorian grit. The busiest section of the West Coast main line is now 182 years old.

Trains are assembled, Meccano-like, in immaculate factories; half-a-mile of track can be renewed overnight by pushing buttons. It’s effortless, comparatively. But the grand structures that still circumvent landscape barriers were crafted by man’s hand in inconceivable circumstances. There was no task briefing or competence regime. There was no welfare cabin or weather-proof gear. There was no handrail or fall-restraint harness. There was no crawler crane or telehandler. There was no certainty that you’d see the end of your shift.

Over the top

Arguably, the greatest triumph of our railway-building exploits overcame the bleak terrain of the North Pennines to connect Settle with Carlisle, 73 miles away, via 20 viaducts (depending on your definition) and 7,000 yards of tunnel.

The line was born of the obstructive rivalry suffered by the Midland Railway at the hands of the London & North Western, whose line it relied upon for access northwards from Ingleton – a small Dales village where the two companies built stations at either end of a viaduct. Passengers faced a stiff walk from one to the other before an agreement eventually brought the coupling of the Midlands’ carriages to L&NWR services, often dawdling goods trains. It was no way to run a railway.

Anchor ©FourByThree.

In frustration, an independent route was surveyed and approved, but, as interest rates soared in a bank failure’s aftermath, the Midland petitioned Parliament for permission to abandon the scheme. Refusal prompted a start to construction in November 1868, with the venture set to cost £2.3 million – a snip at £237 million at today’s values.

Moorland suburbia

Batty Moss nestles beneath Yorkshire’s twin peaks of Ingleborough and Whernside. Horton-in-Ribblesdale is five miles distant, Ingleton six miles and Hawes ten. The middle of nowhere is thus defined. Curving elegantly across the bog for quarter-of-a-mile is a 24-span viaduct, now known universally as Ribblehead, reaching 104 feet skywards and 25 feet into the earth.

GroutMix ©FourByThree

It was Grade II* listed in 1987, whilst the land to its east is designated as a scheduled ancient monument. Here, the navvy encampments of Belgravia and Sebastopol were intersected by a network of two-foot gauge tramways laid to benefit construction; two more – Inkerman and Batty Wife Hole – were found a stone’s throw further south.

The 1871 census records 900+ men employed on this section of line; the camps offered shelter to around 2,300 at peak times. Hereabouts were a hospital, post office, library, mission house, schools, shops and pubs, alongside the offices, stores, stables, quarries and brickworks that served the engineering activities.

Cementitious grout is injected under pressure around Cintec anchors, installed at 12 locations along the structure. ©FourByThree

Insatiable appetite

When an adventurous correspondent journeyed here from London in October 1872, the viaduct’s southern approach embankment was well advanced and a bridge through it completed. Extraordinary scenes then took his breath away.

“A number of low, wooden huts, covered with tarred felting, have grouped themselves together without pretence to arrangement on either side of the road that winds down rather steeply from the archway to the little pool formed by the head waters of the Ribble, as they spring out of the limestone rock.”

Many of the navvies killed at Ribblehead are buried in the graveyard at nearby Chapel-le-Dale.

This was Batty Wife Hole with its 74 dwellings, a settlement commemorating the legendary demise of a local woman whose husband – Mr Batty, who lived on the fells – did away with her in the ‘churn hole’ from which the stream emerges.

“Great square-shouldered rough-faced men, with slouched billycocks, knotted kerchiefs, very short moleskin trousers and tremendously stout ankle jacks, come lurching out the huts and stride heavily through the oozy moorland to the scene of their work.

“The navvy works hard – ten hours a day, and no lazy pottering when he is at work – and he insists upon living well, as he has indeed a right to do. He has his four meals a day, and meat with every meal. In one house in Inkerman, where there are eight navvy lodgers and a family besides, the consumption of butcher’s meat is over 100lbs a week.”

Living on the edge

Our correspondent ventured up the tramway to behold the men’s industry. “The line is a temporary way which winds deviously across the hollow, already partly spanned by the huge skeleton viaduct. I scramble along somehow, through knee-deep bogs, on to piers whose foundations are just level with the surface, past batches of stone-hewers hammering away industriously at great blocks of blue stone for the piers of the viaduct; then I find myself amongst these, and in the labyrinthine scaffolding that encircles them – looking up at trucks and engines traversing tramroads at a dizzy height, at derricks and blocks, and pulleys, at noisy little fixed engines, and at silent busy masons.”

It’s thought that more than a hundred navvies succumbed here, through calamitous mishaps, smallpox outbreaks and conflicts fuelled by alcohol. They fought as hard as they worked. Church of England records indicate around 200 burials of men, women and children in the nearby graveyard at Chapel-le-Dale; unmarked graves are thought to be scattered across the moor.

The price paid by those who gifted us our railway network against all odds is a debt we must never lose sight of.

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Back from the dead

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A hundred wild winters took their toll on Ribblehead Viaduct, its masonry impacted by water ingress. Repairs were undertaken sporadically through the 1980s, with linespeed reduced to 20mph over a single track to centralise the loading. When British Rail proposed the route’s closure – citing the high maintenance burden of its major structures – the energetic Friends of the Settle-Carlisle Line was established to mobilise public opposition. Its reprieve came in 1989 and the viaduct underwent major refurbishment in the early Nineties, led by resident engineer Tony Freschini.

Today, the structure tells the story of its own evolution, with an assortment of metal fixtures, concrete quoins and red brickwork patches. It’s stood up well to the subsequent 30 winters, but another intervention is now underway, making good the defects that time inevitably perpetuates.

The remit was lodged with the Works Delivery team for Network Rail’s North West route a couple of years ago, resulting in examination reports being studied, site surveys undertaken and drawings produced. A base model for the viaduct was created from as-built records and a LiDAR resource covering the entire route, obviating the need for a specific topographical survey; however, using a drone, Commendium subsequently generated an impressive 3D scan of the viaduct, working alongside heritage consultancy firm Wardell Armstrong.

Site mobilisation got underway in October and saw the establishment of a compound on pre-existing hard-standing at the south-east corner of the viaduct. A no-dig haul road, comprising MoT Type 1 stone, was laid on a geotextile along its west side.

Longitudinal fractures mid-span have been stitched, cleared out and repointed. PHOTOS: FOUR BY THREE

Touching distance

The greatest challenges here arise from the structure’s location, scale and restrictions imposed due to its listed status. The cost of scaffolding every part of it would likely have exceeded the scheme’s £2.1 million budget; it was therefore decided to focus activity where the priority was highest, covering Spans 4, 9, 10, 12, 13, 14 and 18 (numbered from the south), the piers to both sides of those spans and an isolated pier between Spans 5 and 6. The sequencing would generally involve repairing one span whilst the scaffolding was erected for the next and dismantled at the last.

A condition of the listing building consent requires “the character, appearance and historic significance of the Ribblehead Viaduct” to be “retained and conserved”. In practical terms, this means that the repairs mustn’t visibly alter the structure in any material way whilst the temporary works have been non-invasive – so no tying into the masonry or excavating foundations.

To address these constraints, scaffold designers RDG Engineering specified aluminium tubes to reduce loading by about one-third. This brought manual handling benefits for the construction staff from QED Scaffolding, as well as reducing the number of deliveries from the firm’s depot in St Helens; it did, however, require the use of double standards (two vertical legs) to share the load. Scaffolding one span typically took 19 days.

Due to listed building constraints, the scaffolds could not be tied into the structure.

Sitting 300 metres (984 feet) above sea level, the area around the viaduct is unsurprisingly prone to storm-force winds. Although the tubing could abut the stonework, there would remain a tendency for it to twist under wind loads of 1.16kN/m2 – double the typical value – so the scaffolds were stiffened by installing chains of plan bracing.

It’s a notable aside that Brian Eades, QED’s managing director, helped to facilitate the viaduct’s Nineties restoration – when the scaffolding stretched from one end to the other – and has been on site a couple of times a week throughout the current project.

Getting it right

You might regard this as housekeeping on a grand scale. The shopping list for remediation read as follows: remove vegetation and roots, rake and repoint open joints, stitch and grout fractures within the brickwork, insert concealed anchors, cut back and renew spalled masonry, and install stitching bars through cracked voussoirs. All of these solutions were mixed and matched, as required, to meet the needs of each span – getting on for 200 interventions in total. And throughout the structure, external metalwork was repainted and the water management system maintained.

Again, the imperative was to work sympathetically with the structure. The mortar specification of four parts quicklime to 11 parts Nosterfield sand and one part clinker – with the addition of a natural clay pozzalan to 10-15% of the volume – arose from laboratory analysis of ten samples taken from three piers and two arches. Five different mortar types were discovered, from the original lime mortar to the Pozament used extensively for the Nineties refurbishment.

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All this is indicative of the care and attention now demanded by planning authorities when working with heritage structures, particularly those with such iconic status. For example, the listed building consent required open joints to be raked out using hand tools before the colour-matched mortar was manually applied and hit with a stipple brush to consolidate it.

A happy consequence of this approach is that it avoids the introduction of stiffer local anomalies within a structure through the use of materials much stronger than the original. This was an unfortunate strategy in days gone by and, in the long term, often made matters worse. Many structures have thus suffered.

The viaduct’s 108 pattress plates have been prepared and repainted, whilst 46 drainage hoppers have been replaced. PHOTOS: FOUR BY THREE

Pull yourself together

At Ribblehead, it can be observed that the tie bars inserted through each span either side of the crown seem generally to have prevented the voussoirs separating from the arch – an issue seen on many viaducts – but longitudinal fractures have appeared in the brickwork lower down towards the piers.

Resolving these has involved the stitching of reinforcement bars across fractures recorded mid-span – adopting a Network Rail standard detail repair – whilst, closer to the edges, around 80 Cintec anchors have been installed at 12 locations along the structure. These are stainless steel bars in woven polyester sleeves, into which a cementitious grout is injected under pressure. The sleeve restrains the flow and expands to about twice its normal diameter, moulding itself into any spaces within the brickwork to provide a mechanical bond, thus dispensing with the need for pattress plates.

Holemasters have undertaken the drilling works. Beyond the obvious access difficulties of getting water barrels, power and tools to the required height, their staff had to contend with a prohibition around the mounting of rigs onto the structure. Instead, each three-metre-long core – 40mm in diameter – had to be hand-drilled horizontally using an assortment of bits and extensions, through the voussoirs and into the arches’ five brick rings. Once the anchor was installed, the repair was rendered invisible by grouting the outermost 50mm from the core back into the hole as a plug.

The 24-span structure across Batty Moss extends for quarter of a mile and reaches a height of 104 feet. PHOTO – MATT KIRBY

Ben Campbell, Network Rail’s programme manager, makes a couple of crucial and intriguing observations at this point about hidden critical elements. Firstly, they highlight the importance of effective records management – and the need to consult those records – to ensure we don’t forget they’re there.

Secondly, Ribblehead’s tie bars were installed decades ago, though precisely when we don’t know. “What condition are they in? How corroded are they?” he asks. “They’re inside a structure that’s largely waterproofed, but we’re having to assume they’re still good. Can we do some form of in-situ non-destructive testing of tie bars to see whether they’re intact across their whole length? It’s a risk for the railway industry and something worth looking at.”

Finishing touches

Hanging over the parapets throughout my visit were rope-access specialists engaged by Industrial Coating Services (ICS), supported by Teesside Industrial Services. Secured to one-tonne kentledge blocks placed trackside during possessions, these high-flyers were wielding needle guns and grindettes to mechanically prepare some of the 108 pattress plates which were subsequently cleaned and repainted, along with a further 360 pieces of exposed steelwork. ICS’ contract for this part of the scheme included the replacement of 46 drainage hoppers and painting the associated downpipes.

Specified was a winter-cure system from Jotun involving primer and intermediate coats – suitable for application at temperatures below 5°C – and a gloss finish coat which requires warmer conditions, not often experienced here over the wintertime. The system offers a 15-year lifespan. To minimise potential disruption from high winds, the team set up for work on both sides of the viaduct so there was always a sheltered side available.

The hardy explorers who pass beneath Ribblehead Viaduct before climbing up Whernside will see nothing of these labours once the scaffolds are gone and cabins removed. That’s the point, of course – the heritage regulators demanded seamless engineering here. But you can’t change history. Up close, the structure’s hodgepodge appearance reflects the railway’s efforts to stave off the impacts of 145 years’ weather and traffic loading. Step back though and a peculiar harmony reveals itself: this monumental feat remains very much at home in an often hostile landscape.


With thanks to Ben Campbell, Andrew Walker, Ian Ross, Samantha Mikhail, James Marlor, Richard Parker and the on-site team for their help in producing this article.

Graeme Bickerdikehttp://therailengineer.com
SPECIALIST AREAS Tunnels and bridges, historic structures and construction techniques, railway safety Graeme Bickerdike's association with the railway industry goes back to the mid-nineties when he was contracted to produce safety awareness videos and printed materials aimed at the on-track community. This led to him heading a stream of work to improve the way safety rules are communicated and understood - ultimately simplifying them - for which he received the IRSE’s Wing Award for Safety in 2007. In 2005, Graeme launched a website to catalogue and celebrate some of the more notable disused railway structures which still grace Britain’s landscape. Several hundred have since had their history researched and a photographic record captured. A particular focus has been the construction methods adopted by Victorian engineers and contractors; as a result, the site has become a useful resource for those with asset management responsibilities. Graeme has been writing for Rail Engineer for the past ten years, generally looking at civil engineering projects and associated issues. He has a deep appreciation of the difficulties involved in building tunnels and viaducts through the 19th Century, a trait which is often reflected in his stories.

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