We take for granted the transport infrastructure that gives us the freedom to move swiftly (congestion delays aside) around the country. The road and railway networks allow us to travel to the coast, attend major events, visit family and friends. It also brings us all the commodities we need for daily life. But day-by-day the system, like us, gets a little older. For instance, the iconic elevated motorway system at ‘Spaghetti Junction’, the Gravelly Hill Interchange in Birmingham, is now 45 years old and requires regular monitoring to ensure that it remains fit-for-purpose whilst dealing with ever increasing traffic flows.
“Motorways in the 1960s were built quickly and for many fewer vehicles than are using them today,” says Ryan Bradley, concrete inspection expert and director of Derby-based Inertia Consulting. “Change is required to deal with the increased traffic, such as the construction of four-lane smart motorways, and this has pushed the heavy goods vehicles out to the hard shoulders, increasing loading on the structures.”
With thousands of bridges and concrete structures supporting our transport infrastructure, the task of conducting regular inspections is a mammoth one, and highly specialised, and vital. Inertia Consulting have quickly established themselves as leaders in their field and have also picked up some prestigious awards for their sensitive approach to some more historic structures.
“As engineers it’s nice to have someone say ‘You’ve done a lovely job of that,’” says Inertia’s founder and co-director David Roome after collecting a string of awards for their restoration of the historic Ferry Bridge in Burton.
Laser scanning of the 20 megalitre underground reservoir for structural capacity assessment, Cambridgeshire (photo: Inertia Consulting)
Confined spaces survey for structural alterations to a water pumping tower, Kettering (photo: Inertia Consulting)
Inertia Consulting’s growth has been rapid after establishing a sound reputation within the transport sector. “It began 10 years ago as a back-bedroom thing,” David says. “I was working for large consultants, multi-nationals, on bridge engineering and I saw there was an opportunity to provide more of a personalised service. Corporates can sometimes become faceless and we found that there were small-to-medium businesses, and large corporates, who wanted to pick up the phone and be helped out.
“We started at the worst time, 2006, just as the recession hit, but we grew through the recession as we have, year-on-year, for the past ten years. Initially we were doing office-based design for bridges, but as one of my specialisms is in advanced analysis and historic structures we quickly began picking up projects in these areas.”
One of Inertia’s early successes was the restoration of the Wilford Suspension Bridge in Nottingham. This brought Derby-born David into contact with Ryan from Matlock. The project won a national award with the Institution of Civil Engineers.
After working together on several subsequent projects, David invited Ryan to join him in the business. With Ryan’s specialist expertise in the non-destructive testing and inspection of concrete structures, Inertia secured a position on the supply chain as inspectors for Area 9 of Highways England’s road network, Birmingham and the West Midlands including ‘Spaghetti Junction’, working for the area’s managing company Kier Group, together with other similar commissions throughout the UK.
Difficult access inspections and non-destructive testing of the Ashopton Viaduct, High Peak, Derbyshire (photo: Inertia Consulting)
“Techniques have changed since the 1960s and the industry realised that there was this big boom of construction and they put all these highways in, but the way they were constructed helped to accelerate corrosion and reduce the life,” Ryan explains. “Engineers are constantly working to retrofit and repair what’s already corroding, replace bits which are wearing out and strengthen it for new things like smart motorways that are now running four lanes on top.
“Structures like ‘Spaghetti Junction’ and the Hammersmith Flyover, which was in a very poor state and needed strengthening before the Olympics, can’t be easily replaced. The management of the assets is a constant battle, working out where to spend the limited money, and planning the life of the structure. We give clients the data and the technical support and expertise to say ‘we think you should do this, don’t worry about that for now, but you will have to target it in five years.’ It’s planning how to use the limited budget for two to three thousand bridges, and how you do it whilst making sure that it’s safe.”
“Just to get to the structure can be really difficult,” David adds. “On occasion, we’ve gone to look at a structure and it’s nothing like it should be. Details can be hidden, changed, or records incomplete. It can be a bit like Sherlock Holmes! We use a multitude of techniques, from traditional methods such as callipers, tapes and drilling holes; right through to advanced radar systems, high-end expensive equipment.”
Ryan explained the varied nature of Inertia’s work. “The aspects of bridge engineering include pure design, which we do a lot of, assessment of existing structures and strengthening with projects like Ferry Bridge. To get to that point we must undertake the routine surveys. By law, local authorities must inspect bridges every two years with a touching distance survey of the whole thing every six years. That is the core of the business. We have our own power boats, we will build pontoons, we hang from ropes. The furthest we have been is Iraq taking around half a ton of luggage. We had a phone call just before Christmas a few years ago, wanting to see if a bridge could take a heavy load for an oil project out there. On the 5th Jan we were in Iraq with rope access, a boat and a large team. We half-scared Austrian Airlines with the sheer amount of kit we had!”
“We get into some amazing places. We were in some structures recently, that were very lively. You’re in a dark confined space and when a heavy load goes over above you it starts the structure moving. Whilst its safe, it still makes you start twitching a little bit!” he laughs.
Ryan Bradley indicates the two structures of Burton’s Ferry Bridge
David and Ryan initially shared an office in Matlock with another engineering concern before the need to expand brought them to their present location, a 1930s art-deco property on Stafford Street in Derby. The building was in a poor condition, used as a squat, but Inertia spent a considerable amount on restoration and saved the building. “A developer wanted to rip it down and build some flats, so it’s quite nice to have saved it,” says David. “We are seeing a massive difference in the Friar Gate area which is really bustling now, and we’re so close to the town. We could move the company anywhere, it wouldn’t affect the business, but we like it here.”
The Inertia Consulting team outside their Stafford Street offices
Over the last couple of years Inertia have grown to a staff of twelve, headed up by principal engineer Tom Krok. Having qualified through an apprenticeship scheme with Tarmac, David is keen pass on those same benefits as his team develops. “We want to do the same with our staff. We’ve put one engineer through a degree, so far, another is doing his masters, while a third has just completed his apprenticeship with us. Despite being a small firm, we are now an ICE accredited training company. We will support staff to become chartered or incorporated, whatever level they want to get.
“That’s important. A lot of companies are very profit-focused but we say it’s about people above all else. We make sure the staff’s kit, our working environment and their training is top quality. We also operate flexibly with the staff as we understand that people have families. It’s important that the staff are there at important times for the family.” Whilst the nature of the work is important and quite intense, the office environment is relaxed and informal. The company itself has a strong family atmosphere perfectly illustrated, recently, when Ryan invited the whole company to his wedding.
Beyond the main transport infrastructure, Inertia have been involved with a variety of other projects including looking after the Derwent Valley aqueduct, part of the Derwent Dams complex, as a regular contractor for Severn-Trent, the Docklands Light Railway, Gatwick Airport and, ahead of the London Olympics, Inertia designed long-span flooring in the media centre car park together with the entrance gantries.
“We’ve also designed some advertising structures in Edinburgh, for JCDecaux, as a new design for gateway structures near the airport – huge TV screens with adverts.” says David. “We have several projects in Devon where we are putting new footbridges in, one over the M5 later this year, and we’ve just finished the superstructure design for one over the A39, the Atlantic Way near Barnstaple, and completed the steelwork design for a new mainline station in London.”
Spinningfields Footbridge, Salford, Greater Manchester, Inertia designed all temporary works for this complex project (photo: Inertia Consulting)
Inertia are also involved in temporary structures design including the A465 Heads of the Valleys road scheme in South Wales and the lift design for the new bridge across the A50 in Uttoxeter. “That was a 135 tonne lift, the biggest single span structure to be delivered in the UK. We did all the temporary-works design which is lifting systems and stability while you lift. It was one of those moments when you are happy when it’s gone in. Some temporary works for curving bridges are the size of a ten-storey building, big structures. Ground conditions can be difficult because of the topography, some can be on the edges of cliffs. It makes for an interesting life and it’s good for the team.”
Following their early success with Wilford Suspension Bridge, Inertia were contacted by Staffordshire County Council to look at the 1889 Ferry Bridge across the River Trent, a well used footbridge connecting Burton town centre with nearby Stapenhill. “They knew the structure was deteriorating,” says David. “It was having regular maintenance, but they wanted a capacity assessment. We ran a computer programme to see which bits were over-stressed and then looked at how to deal with the issues of where it was overloaded.
The Ferry Bridge provides a vital footpath between Burton-on-Trent and Stapenhill
“To do this we carried out a principal inspection with pontoons and a boat on the river, diving teams in the water to look at everything. With historical structures sometimes the modern analysis will say the structure doesn’t work which is because the computer can’t model how the old structure behaves because it is too complex.
“We spent months assessing it and then looked at how the Victorians did it. There were several different structural systems holding the bridge up. We chose to look at each separately, whilst also accounting for each system being interdependent on others. This approach enabled us to save the client a lot of money on the strengthening. It’s a Grade II Listed structure so we had to get Listed Building consent to do any works to it, all of which must be sympathetic to the structure. After the first assessment it went quiet for a few years while they got the funding together, so then we had to re-assess the bridge.”
A single bolt at the points where the new structure supports the old
The bridge was closed for 12 months while Inertia site supervised the £1.3 million restoration work on the bridge. “We put a new structure inside the old and at each strengthening position were able to use just 2 bolts. The old structure had only to support some of its own weight. The new structure looks like part of the parapet and takes all the load from the foot traffic across the bridge.”
Hundreds gathered to see the re-opening of the bridge on 21 October 2016. “That was great to see,” said David. “I’m amazed just how heavily used it is.”
“It is a superb job, money well spent,” said Councillor Simon Gaskin, Deputy Mayor of the borough council. “It would have been a very sad loss had they not spent money on it and renovated it. It would have been left closed and dismantled. It is a feather in the cap for everyone involved.”
Ryan and David with some of the awards they have collected for their work on the Ferry Bridge
The Ferry Bridge project has collected a number of prestigious awards for Inertia Consulting including The Institution of Structural Engineers, Midlands Counties Regional Group, Structural Awards Winner (Pedestrian Footbridge) and the ICE West Midlands Heritage Award. “I like that kind of project because it’s giving back, in a way,” says David, “and you know it will be there for at least another hundred years.”