Storm Desmond was Cumbria’s biggest on record and devastated huge swathes of infrastructure. Lucy Alderson finds out how work is progressing as the rebuilding programme reaches its halfway point.
In December 2015 just before Christmas, Cumbria was devastated by the biggest flood in the county’s history.
Storm Desmond raged through the North-west, with around 1.15tn litres of rain falling in just six days – enough to fill Wembley Stadium nearly 300 times over. Some 7,790 families were evacuated from their homes and more than 2,000 businesses were affected.
Although flooding is common in the region and localised strategies were on standby, Cumbria County Council was not prepared to tackle damage on this scale. No response plan was in place to begin rebuilding the county’s broken infrastructure, which was causing the local economy to haemorrhage money.
The council says that £86,000 a day was lost as a result of the damage to and subsequent closure of Eden Bridge, one of the three main crossings in Carlisle. The local business community estimated that the closure of the A59, which lasted five months, was costing £1m a day.
Reconnecting the county was a matter of urgency. The government approved £123.6m of emergency funding for Cumbria County Council to repair and rebuild its broken bridges and highways under its Infrastructure Recovery Programme (IRP).
Mott MacDonald is responsible for the overall programme and project management of the programme, in partnership with the council. The consultant is also overseeing management of the supply chain – all of whom are tier two contractors – to deliver the works.
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The programme is now at its halfway point. But the nature and scale of works have been unique, making it necessary for the team to develop new technology and upskill local firms to tackle the damage.
Data maps Cumbria devastation
“This was well beyond a business-as-usual job,” says IRP programme delivery manager Ian Rowley.
When the Mott MacDonald team arrived in Cumbria in January 2016, it quickly realised the scale of work needed even before construction could start. Around 1,600 surveys of roads and bridges were conducted and £121m of work identified. In total, 784 bridge repairs were required and a staggering 240 km of roads needed resurfacing – 4 per cent of the county’s entire network.
“When the programme ends, the council will then be left with a suite of collaborative contractors on their framework”
Ian Rowley, IRP
“We needed a system to prioritise work,” Mr Rowley explains. “This was a case of: where do we start?”
To solve this question, Mott MacDonald deployed its geographic information system for major projects: GiGi. By mapping the area’s terrain, road network and bridges, then inputting data from asset surveys and assessments, the team could begin to organise a hierarchy of works to be completed. Traffic volume, community buildings, bus routes and economic impact relating to these assets were also logged onto GiGi.
“Building data around these assets up enabled us to take a scientific approach as to why we were targeting specific locations instead of others,” says IRP GIS manager Andy Sheekey.
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Packages of work were split up according to region, with contractors appointed to the IRP framework ready to access the platform to update their progress and new information on their schemes. “GiGi means there’s no multiple spreadsheets floating around; there’s only one version of the truth available,” he says.
Cumbria subcontractors upskilled
Eight contractors are delivering the IRP programme and 72 per cent of all contracts awarded have been given to the regional Cumbrian supply chain – a conscious decision from the outset, according to IRP project lead Matt Pearson.
These eight contractors were already on an existing council framework and could therefore be mobilised quickly. But the critical challenge was equipping these firms with the necessary skills to tackle the works. “The tier two contractors we have do not have much experience of managing designers,” Mr Pearson says. “They may not have done design-and-build contracts before or have predominantly worked as subcontractors for tier ones.”
Under pressure to start work immediately, the central IRP team needed to work quickly to help upskill these firms. “We sit down with them, ask them where their stresses and strains are, and work with them,” Mr Rowley explains. “It’s about being honest with each other. We suggest what they need to develop and explain how to do this.”
Who’s working on IRP?
AE Yates | Coffey | Eric Wright Civil Engineering | Esh Construction | Jacob Stobbart | Metcalfe Plant Hire (Civil Engineering) | Story Contracting | Thomas Armstrong Construction
Capita | Curtins | Kier (providing design support to Metcalfe Plant Hire) | Mott MacDonald | RG Parkins
To provide structure and guidance for contractors delivering projects, the IRP team created flowcharts for the processes behind the design, construction and completion phases. This has helped contractors deliver 452 projects to date – approximately a third of the programme – with another 409 in progress and 373 that are still to begin.
This collaboration and upskilling process has seen the council establish stronger relationships with its local supply chain, and enabled contractors to be equipped with the necessary skills to rebuild infrastructure should another major flood occur.
“It’s helped us move from a transactional to a more collaborative relationship [with the local supply chain],” Mr Rowley says. “When the programme ends, the council will then be left with a suite of collaborative contractors on their framework.”
Robot arm inspects bridges
It became clear in the aftermath of Storm Desmond that faster ways of investigating damaged infrastructure were needed.
Traditionally, divers have been deployed to inspect whether scour damage (erosion of riverbeds that could compromise the stability of bridge structures) has occurred following major flooding.
However, due to the risk of putting divers into fast-moving water, it can be weeks or even months before bridge damage can be assessed and work can subsequently commence.
Eden Bridge is one example of this. It became apparent towards the end of December 2015 that divers would not be able to inspect the bridge, which is one of Carlisle’s most important infrastructure links, for months.
“We’re keen to pull together an end-to-end study to go out to the industry, government and anyone working in infrastructure”
Stephen Hall, Cumbria County Council
The River Eden’s flowrate did not return to safe levels for divers until the end of March. But to wait until then would have been catastrophic for the community and economy of Carlisle, according to Cumbria County Council highways transport and fleet assistant director Stephen Hall.
An alternative method of bridge inspection was required, which led the IRP team to develop BridgeCat.
BridgeCat is a robotic arm attached to an HGV that can be used to inspect underwater bridge damage. On the end of the arm is a high-definition sonar camera, and the IRP team can lower the camera into fast-moving water to check underneath the bridge structure for scour damage. Meanwhile, drones can be used for inspections above water to check whether damage has been caused to bridge parapits and piers.
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Although still under development, Mr Hall says this new technology will save huge amounts of time and will eliminate the risk of human error that exists when using divers.
“Diver-based scour assessments rely heavily on the competence of the operative,” he says. “You’re essentially putting someone underwater with a metre ruler to tell you how deep the hole is when the bridge is damaged. [With BridgeCat] you’re largely eliminating human error and you’re also not putting someone at risk when they are placed in fast-running water.”
Cumbria’s future flood resilience
After such a devastating disaster, it was essential for the IRP team to go above and beyond simply rebuilding Cumbria’s infrastructure. One of the objectives was to make sure the council and its supply chain could improve its response to flooding and ability to repair damage themselves.
An analysis of how work was delivered under the programme will be fed back to the Department for Transport, offering a guide on how to quickly mobilise a workforce to repair infrastructure following a similar crisis. This report will include the flowcharts contractors have used to help them conduct work as an example of an effective contractual strategy to approach flood repairs.
“We’re keen to pull together an end-to-end study to go out to the industry, government and anyone working in infrastructure,” Mr Hall says. “We want to show how Cumbria did it, the challenges we faced and what worked [on the programme]. We are keen to share this methodology and the lessons we learned.
“After all, when your county is devastated, you have to deal with it and find the silver lining to these problems.”
Bridge repairs: 3 major job
Brougham Old Bridge
Brougham Old Bridge was the most technically challenging aspect of the whole IRP programme to date, according to IRP project lead Craig Mitchell.
A thorough assessment of the bridge was needed before construction could start, as the initial understanding of the Grade II-listed structure was very limited. “Our main concern was understanding how the bridge was still standing and whether it was safe enough for the team to start works,” Mr Mitchell says.
The bridge was nearly totally lost after Storm Desmond and urgently needed temporary works in order to be stabilised. The team pumped 80 cu m concrete under the pier to prevent it from collapsing and to fill the scour hole that had formed after high-pressure water flow. Penrithe sandstone meanwhile was used to repair the partially collapsed archway.
Pooley Bridge is the “jewel in the programme’s crown and a critically important project,” says IRP programme director David Brown.
The entire bridge collapsed during the floods, severing access to the north part of Pooley town. A temporary bridge was built in February 2016 but construction of the final bridge will begin at the end of 2018 – the last project to be delivered under the programme.
After six months of extensive community engagement, the design for the final bridge was decided: a stainless steel crossing will replace the previous stone arch to provide a more resilient structure.
This Grade II-listed bridge was weakened during Storm Desmond and finally collapsed in January 2016.
One of the key challenges was moving overhead powerlines to construct the bridge structure, for which a 30-tonne crane was used.
Planning applications were lodged with two borough councils and central government for the works, which saw the team pump around 40 tonnes of concrete into a vein running through the bridge’s central structure to provide a resilient structure.
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