Alternative segment lift for HS2’s Colne Valley Viaduct minimises local disruption

Construction of High Speed 2’s (HS2’s) 3.4km long Colne Valley Viaduct has reached a major milestone with a key 40m long span lifted into place over a local road during a three week closure of the route.

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Marathon’ bridge build completed on HS2

Contractors on HS2 have completed a ‘marathon’ bridge build at Streethay near Lichfield involving 18 specialist construction companies.



Work involved excavating 14,000 tonnes of earth, building a 140 metre retaining wall and moving a 2,600 tonne bridge deck 130 metres into place under the South Staffordshire freight railway.

The work was carried out during a 10 week blockade. It was completed by HS2’s civils contractor in the West Midlands, Balfour Beatty VINCI, and designers Mott MacDonald as part of a Design Joint Venture with SYSTRA (MMSDJV), together with teams from 18 specialist supply chain companies.

At the end of July, the 2,600 tonne bridge deck, which had been cast on land adjacent to the railway was moved 130 metres into position using self-propelled modular transporters.

Since then, each side of the bridge was backfilled, the rail tracks were reinstated, with the railway line was successfully handed back to Network Rail last week and now reopened.

The 25 metres long and 18 metres wide Streethay overbridge sits within HS2’s Streethay cutting and will enable HS2 trains to travel under the existing railway between Birmingham and Crewe.

Through design development, Mott MacDonald engineers were able to reduce the total length of wall structures for the railway at Streethay from 1.6 kilometres to 420 metres, meaning 80% less concrete is needed – saving around 420,000 tonnes of carbon, supporting HS2’s ambition to cut carbon on the project.

The Streethay bridge sits on top of the larger 420 metre long retaining wall structure which will have two additional bridges crossing it – the south bound A38 slip road bridge, and the Rykneld Bridge which carries the A38 north bound slip road and the A38 north and south bound carriageway.

At its peak, over 150 people worked on the complex construction operation, with teams from 18 specialist companies, delivering design, surveys, piling works, bridge build, concrete pouring, crane operations, reinforcements, modular transportation, track and systems removal and reinstatement.

The work was delivered in parallel to the construction of the nearby Fulfen Wood bridge, which involved moving a giant 6,200 tonne single span structure under the West Coast Main Line – the UK’s heaviest drive to install an intersection bridge.

David Millar, Rail Interface Manager at Balfour Beatty VINCI said: “The successful delivery of this complex and challenging piece of engineering near Lichfield is another proud moment for Balfour Beatty VINCI on the HS2 project.

“It’s only been possible thanks to the skill, dedication and support shown by the project team over the past few years, including our supply chain. Together, we’ve had to work around existing transport infrastructure, including the South Staffordshire freight railway and the A38, making this achievement even more rewarding.”

Prior to the railway blockade, retaining walls were installed on either side of the railway, enabling the areas to be excavated. The bridge deck was constructed on land adjacent to the existing railway, 130 metres from its final position.

Once the railway was closed to freight trains, the track and embankment were removed. Bachy Soletanche Balfour Beatty Ground Engineering joint venture then installed an additional 76 secant piles measuring 1.3 metres diameter and 30 metres deep, linking to the piles they installed prior to the blockade, to create two retaining walls which act as the walls for the bridge.

A concrete capping beam was installed over the retaining walls, then the bridge was moved into place using self-propelled modular transporters with 344 wheels. Concrete was poured to attach the deck to the capping beam, the embankment was back filled using 2,500 tonnes of structural backfill, on either side of the bridge, before the railway line was reinstated.

The 18 companies which delivered the project were:

J. Murphy & Sons constructed the bridge deck and the concrete elements during the blockade
Bachy Soletanche Balfour Beatty Ground Engineering JV (SB3) undertook all piling works, both before and during the blockade
The bridge parapets were made by Explore precast
Podtrak and RSS Infrastructure delivered rail systems work
Balfour Beatty VINCI delivered earthworks
Pile break-down was by Pile Breaking Systems UK Ltd
Trackway supplied by TPA
Jacking the structure and modular transportation by Mammoet UK
Survey works track monitoring by Aecom
Crane supply by King Lifting supported by BBV lifting teams
Concrete provided by CEMEX
Reinforcement by ROM – specialist reinforcement manufacturers
Temporary works by RMD
Permanent works design by Design JV (Mott Macdonald and Systra)
Temporary works design by Taylor Woodrow

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Innovation Showcase | Track-free travelling formwork drives pace of HS2 green tunnel work

Innovative moving formwork is helping to speed construction of High Speed 2’s Copthall Tunnel in north west London.

Copthall Tunnel is one of five green tunnels being built along Phase 1 of High Speed 2 (HS2) between London and Birmingham.

Situated between HS2’s Northolt Tunnel and the Colne Valley Viaduct, the 880m long reinforced concrete Copthall Tunnel will blend into
its natural surroundings, covered with trees and plants once construction is complete.

The project is being delivered by Skanska Costain Strabag Joint Venture, with Kilnbridge appointed to complete the reinforced concrete works. Making the tunnel a concrete reality has been possible with custom formwork travellers engineered by Peri’s specialist infrastructure team.

As the travellers were expected to be in use over an 18 month period, the main drivers influencing their design were durability, productivity and sustainability.

To support the specified construction sequence, Peri’s engineers designed two carriages which enabled the site team to cast the walls and roof slab simultaneously, ultimately accelerating the programme. These carriages comprised four units in total, two for the wall and two for the roof.

The carriages are designed to reduce material, manual labour and craneage as the main operations such as striking, positioning and travelling are completed hydraulically.

The wall forms are built from special modular steel panels. Each set is designed to build 20m long and 7.5m high walls.

The panels are suspended from a carriage which is designed using off-the-shelf components from Peri’s Variokit range, with some specially fabricated connection parts. Variokit rails provided additional support for the formwork, reducing through ties to less than half the quantity required in a traditional panel system.

“We’ve been able to save around five days per wall in comparison to traditional formwork systems, as we can complete installation and prepare the system for concreting in one day,” says Kilnbridge project manager Teresa Martin.

The internal and external formwork on the wall carriages raise, lower and retract hydraulically, eliminating crane use and reducing labour requirements and cycle time by over 80%.

The roof carriage is built from a mix of special and standard components. In addition to fully supporting the rebar and concrete load, it features hydraulic cylinders which enable the traveller to be lowered, collapsed, pushed under the carriage in front and repositioned to allow rebar fixing and pouring operations to be concurrent. 

Peri senior sales engineer Dan Biggs says: “Special steel formwork was ideal for this project as the forms can be reused up to 30 times, so there is an obvious material saving advantage in addition to time savings, as panels do not need refacing, unlike a
plywood faced system.”

Following on from the installation of the roof traveller, the next steps will be progressing the tunnel so all three elements – base slab, tunnel walls and roof slab progress concurrently without conflicting. Tunnel construction is expected to be completed by February 2025. 

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Meet the company using discarded oyster shells to cut energy costs and keep France’s buildings cool

Cool Roof France has found an innovative way to use the 130,000 tonnes of waste oysters produced every year in France.

As heat waves continue to scorch Europe, many of us are looking for cheap and innovative ways to keep our homes or workplaces cool.

While air conditioning often proves effective, its environmental cost contributes further to the climate crisis.

So what if we look into the past and to other parts of the world for inspiration and startpainting our roofs white?

“This technology is just pretty old actually, but this is quite innovative to make it so technical,” says Julien Martin Cocher, deputy CEO of Cool Roof France.
But does having a white roof really make a building cooler?

What is oyster shell roof paint?

Cool Roof France (CRF) is on a mission toreduce the ambient temperature inside buildingsin a sustainable and cost effective way.

Traditional paint is made up of calcium, solvent and water.

“The oyster was at the beginning just to use a waste that we are finding quite easily in the west part of France and to replace this calcium that we are usually finding [in paint],” Julien explains.

Its innovative team of scientists soon discovered that the oyster shell maximises the paint’s performance and makes it more durable.

Can white paint make my home cooler?

CRF’s oyster-enriched, thermo-reflective roof paint is applied in three layers. The first two layers make it a durable product which will last for around 20 years.

By adding the third layer, the paint is able to reflect 90 per cent of the sun’s rays away from a building.

This results in an average temperature reduction of six to seven degrees Celsius.

“Usually companies areusing ACand when they are using AC, that means that if we are lowering the temperature, we manage toreduce the AC use.

“By reducing the use, we are also dropping down the energy consumption for the AC,” Julien adds.

“So that means, when we are getting minus six, minus seven degrees Celsius we manage to demonstrate that we are getting between30 to 50 per cent less energy consumption, which is huge.”

Cool Roof France has already painted many shop, hospital and office roofs and the results are astounding.

In France, the company has worked closely with the police and government to paint the roof of a sniffer dog handling unit. The ambient temperature of the building was reduced by 10 degrees Celsius.

Last year, schools across Europe wereforced to close because it was too hotfor the children to be inside.

“We shouldn’t fall into this kind of situation,” Julien says.

“We have 1 billion AC (air conditioning units) today. We estimate that we may get 5 billion in 2050.AC is a solution that is making some cold inside the building by making some hot outside.So we are all impacted by this kind of crazy solution.

“Today with a white paint, this is super smart and so easy to implement.”

Can I paint my own roof white with Cool Roof France?

Currently, Cool Roof France mainly works with businesses, schools and hospitals to reduce the temperature inside buildings filled with hundreds of people.

Its staff are able to paint the roof of an office building much quicker than the same area across multiple homes.

By painting many large roof areas white in an urban environment it helps to fight against theurban heat island effect. This is whencities suffer from much higher temperaturesas the heat is contained by tall buildings and large amounts of asphalt. Cooling down bigger buildings can help reduce the overall temperature of a city or town.

But fear not, if you do like the idea of a white roof for your home (and have a love of DIY), CRF also sells its thermo-reflective roof paint via its site.

Using white paint for good around the world

With every building they paint, Cool Roof France monitors and evaluates its product’s performance. It is constantly innovating when it comes to paint.

The company also uses 10 per cent of its profits to help fund projects to support people living in heat vulnerable areas.

“Last year we went to Senegal, painting 30,000 square metres of buildings, schools, hospitals, individual houses and just to help people because this is part of our DNA,” says Julien.

“We just want to make sure that we are going beyond because today we are all suffering from thesedaily heatwaves.”

Watch the video above to learn more about this innovative roof paint.

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FIRST LOOK FCBS completes makeover of world’s first iron-framed building

Feilden Clegg Bradley Studios has adapted the Grade I-listed Shrewsbury Flaxmill Maltings into a £28 million social enterprise hub for Historic England after first being engaged on the project nearly 20 years ago

The Grade I-listed Shrewsbury Flaxmill Maltings was built in 1797 and was the world’s first iron-framed building, a technology developed to give better fire protection.

For nearly a century the site operated as a steam-powered flax mill and was later converted into maltings. During the Second World War the site was used as a temporary military barracks. Following the closure of the maltings in 1987, the future of the site was uncertain before it was bought by Historic England in 2005.

Historic England made it a flagship heritage regeneration project and the former maltings has been gently adapted into a workspace, leisure destination and social enterprise hub.

The project has also introduced a new ground-floor teaching space, which tells the story of the mill’s role in the industrial revolution and world architecture, alongside a café. Above, four floors of offices provide workspaces for 360 people, circulation and meeting space within the former kiln for commercial tenants, as well as access for visitor tours to the restored Jubilee Tower.

The cast iron frame, which had suffered cracking due to settlement and was under-engineered to today’s standards, has been reinforced by strengthening the masonry around the existing iron to enable it to act as an alternative load path in the event of failure. The entire frame has been put back to work through the addition of a hidden steel grillage and six new columns at ground floor level.

Putting the building back to work required comprehensive repairs to the existing fabric and insertion of new core facilities. A light-touch conservation approach was employed to preserve its character.

The pyramidal Malt Kiln, which has many level changes internally, has been converted into a new entrance. This has been left unheated to reduce energy use.

A total of 110 former windows have been reopened. This move, and refitting with new metal windows with high-performance solar glazing, reintroduces natural light and ventilation.

Thermal upgrading of the existing solid masonry walls was researched through on-site trials and hygrothermal modelling. As a result, wood fibre insulation was used to reduce heating costs.

The name ‘Shrewsbury Flaxmill Maltings’, painted in 2m-high lettering across 50m of the principal elevation, was chosen by the community following local consultations.

A heritage skills programme was delivered during the construction works, using the site as a space for learning.

Feilden Clegg Bradley Studios has been working on the project as strategic advisers and architect to Historic England and Shropshire Council since 2003. The scheme won initial planning in 2010. In 2012, the redevelopment (initially costing £52 million) won Heritage Lottery Fund backing.

Client’s view
The commitment, design creativity and attention to detail from FCBS has been impressive throughout the project. Working in close collaboration with Historic England, FCBS has delivered a fine, conservation-led solution. There is now a real sense of pride, and a positive future ahead.
Duncan Wilson, chief executive, Historic England

Project data

Location Shrewsbury
Completion September 2022
Gross internal floor area 5,596m²
Net internal area 4,181m²
Construction cost £28 million
Architect Feilden Clegg Bradley Studios
Client Historic England
Project manager Historic England
Structural and civil engineer AKT II
Mechanical and electrical engineer E3 Consulting Engineers
Landscape architect LT Studio
Quantity surveyor Gleeds
Archaeology University of Salford
Ecology Middlemarch
Catering Cooper 8
Acoustics ION Acoustics
Main contractor Croft Building and Conservation
Embodied carbon New build elements 113 kgCO2e/m² (retained elements kept 886.4 tCO2e)
Predicted annual energy use 136 kWh/m²

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Common Household Waste Product Can Make Concrete 30 Percent Stronger

The potential here is massive and could make civil construction significantly greener.

The use of fine sand in concrete is expensive and unsustainable, but researchers in Australia have found an ingenious solution that is far greener and most of us have it in our houses.
Image credit: ungvar/Shutterstock. 

Researchers in Australia have used spent coffee grounds to make concrete 30 percent stronger. Simply by replacing a percentage of sand with waste coffee, something common to many households, it is possible to make construction more efficient and greener. 

As a household item, coffee grounds are everywhere. It is currently estimated that around 60 million tons are produced across the world each year, most of which is simply thrown away. That’s a lot of waste, and it contributes to the production of methane gas when it ends up in landfills, which contributes to the ongoing climate crisis. There is therefore a need to develop new recycling solutions that can help address the accumulation of this waste. That’s where the work of the team from RMIT University comes into play. 

“The inspiration for our work was to find an innovative way of using the large amounts of coffee waste in construction projects rather than going to landfills – to give coffee a ‘double shot’ at life,” lead author Dr Rajeev Roychand, a Postdoctoral Research Fellow at RMIT, said in a statement.

Because spent coffee consists of fine particles, they were proposed as useful resources for civil and commercial applications. To test the idea, the team collected spent coffee grounds from cafes in Melbourne, Australia, and then dried them. The coffee was then heated through a process called “pyrolysis”, which involves heating organic material, such as a biomass, in the absence of oxygen. This turned the coffee grounds into biochar.

The team then designed 12 mixes to compare the effects the grounds had when made into concrete. This consisted of spent grounds that were untreated (raw), and grounds that were heated to 350°C (662°F) or 500°C (932°F), respectively. These different products were then added to Portland cement at different percentages volumes (0, 5, 10, 15, and 20 percent volume) as a replacement for sand. 

The concrete is then molded and cured at room temperature for 24 hours before being demolded and cured in water tanks to be tested for its compressive strength (to see how far it can be stressed before it fractures) and performance potential. This mix was then analyzed with X-ray diffraction (XRD) and scanning electron microscopes (SEM). 

The results show that a mix consisting of 15 percent pyrolyzed grounds at 350°C significantly improved the structural properties of concrete – around 29.3 percent improvement in compressive strength. 

More work needs to be done to continue developing and testing this method, but it is already showing promise and gaining interest. 

“Several councils that are battling with the disposal of organic waste have shown interest in our work”, Roychand added.  

“They have already engaged us for their upcoming infrastructure projects incorporating pyrolysed forms of different organic wastes.”

A wakeup call for the construction industry

According to the joint lead author, Dr Shannon Kilmartin-Lynch, a Vice-Chancellor’s Indigenous Postdoctoral Research Fellow at RMIT, the results of this study have significant implications for the construction industry across the world. 

“Inspiration for my research, from an Indigenous perspective, involves Caring for Country, ensuring there’s a sustainable life cycle for all materials and avoiding things going into landfill to minimise the impact on the environment,” Kilmartin-Lynch explained.

“The concrete industry has the potential to contribute significantly to increasing the recycling of organic waste such as used coffee.

“Our research is in the early stages, but these exciting findings offer an innovative way to greatly reduce the amount of organic waste that goes to landfill.”

Importantly, the use of biochar in construction projects will relax pressure on the need for fine sand, which is a scares resource across the world. Sand is among the most extracted solid materials on the planet and the second most used resource after water. Moreover, the continued extraction of sand is extremely harmful to the environment.

“The ongoing extraction of natural sand around the world – typically taken from river beds and banks – to meet the rapidly growing demands of the construction industry has a big impact on the environment,” team leader Professor Jie Li explained.

“With a circular-economy approach, we could keep organic waste out of landfill and also better preserve our natural resources like sand.”

The study was published in the Journal of Cleaner Production.

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HS2 will bury two Tunnel Boring Machines at Old Oak Common

Two of HS2’s large tunnel boring machines are to be buried into the site at Old Oak Common next year so they can wait there until a decision is taken about how to build Euston station.

The two tunnel boring machines (TBMs) are needed to dig the two railway tunnels linking Old Oak Common to Euston, but when construction of Euston station was paused earlier this year, there was also the decision taken to delay the two connecting tunnels as well.

Although there’s no practical reason that delaying the Euston station build would require the two connecting tunnels to be delayed, with Euston station effectively on lockdown at the moment it would require the station site to be partially reopened to allow the tunnel portals to be constructed for the TBMs to arrive.

HS2 has also said that delaying work on the Old Oak Common to Euston station tunnels allows them to focus on the section up to Birmingham. There’s also a vanishingly tiny chance that the tunnel’s alignment could be changed to meet up with a redesigned Euston station.

So the two tunnels are also on hold, but to reduce disruption when the two tunnels do start being built, HS2 will drop the two tunnel boring machines into position at the eastern end of Old Oak Common station in readiness for when they are needed.

The two tunnels were expected to start being constructed next year, and as there’s a long lead time on ordering the TBMs, they will be arriving anyway, and installing them into the underground chamber where they will be needed also reduces the headache of storing them somewhere else and then assembling them later.

Placing the TBMs in situ also avoids disrupting Great Western mainline railway in the future, as it will widened as part of the station build, and happens to be running over the top of where the underground chamber needs to be built.

Although it sounds like a major intervention in the plans, and while it is unusual to put a TBM in the ground and leave it there, it’s not unusual to build empty concrete boxes in the ground years, or even decades before they’re needed.

When the Elizabeth line was being built, it made use of the Moor House shaft which was built in 2004 specifically for Crossrail, even before Crossrail was given approval in 2008. There’s also a space under an office block in Victoria ready for when Crossrail 2 opens, and plenty of other examples of holes in the ground being built long before they are needed. All because it’s considerably easier and cheaper to build them early and leave them empty than build them later*, and if they aren’t needed, then there’s a large empty space that will find a commercial use anyway.

The government has committed to opening the extension to Euston, so the TBMs will be switched on. Eventually.

Meanwhile, work carries on to complete Old Oak Common station, with six platforms for HS2 trains and eight at the surface for mainline and Elizabeth line services. Also, an ex-Crossrail tunnel boring machine is about to start digging a tunnel next to the station so that spoil removal and deliveries can arrive without using the roads. Although always required, the logistics tunnel will have added value when the Euston tunnel works start as they will be able to minimise the disturbance to the fit out of the Old Oak Common station.

When Old Oak Common station opens in 2029-33, as it will be the terminus, it’s expected a large percentage of HS2 customers will switch to the Elizabeth line, and TfL is in discussions with the government to secure orders for additional Elizabeth line trains to cope with the large influx of extra passengers.

The date that a modified Euston station will eventually open is not known, but it’s now not expected to be until 2040 at the earliest.

I could add that building the structure for an 11-platform station at Euston and leaving a third of it empty would be a lot cheaper than building a 7-platform station in full and then trying to bolt on a few extra platforms later.

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