Installing a new bridge over the M56 in just one weekend required close supply chain collaboration from the Balfour Beatty Mott MacDonald JV.
Project: Thorley Lane Bridge replacement
Main contractor: Balfour Beatty Mott MacDonald JV
Client: Highways England
Demolition subcontractor: Forshaw Demolition
Steel subcontractor: Cleveland Bridge
Concrete subcontractor: Kilmartin
Lifting subcontractor: Mammoet
Traffic management: Chevron
Project value: £5.8m
Highways England’s pinch-point programme sees contractors deliver smaller-scale targeted improvements to the strategic road network to relieve congestion and improve safety.
But in the process of carrying out projects in the programme, care must be taken to minimise any extra disruption caused by the construction process itself.
This was the task given to the Balfour Beatty Mott MacDonald joint venture appointed to carry out Highways England’s Area 10 Asset Support Contract in 2012.
One of the schemes BBMM has had to carry out is the replacement of the Thorley Lane Bridge over the M56 – a project shortlisted for this year’s Construction News Awards.
The old bridge at junction 5 of the M56 near Manchester Airport had weakened with age and was no longer fit for purpose. BBMM was tasked with demolishing and replacing it – and had to work closely with a number of supply chain partners to deliver the tight 18-month programme on time and with no disruption.
Do what you see
Forshaw Demolition was chosen to carry out the dismantling of the bridge, completing the job over a weekend closure of the M56 back in April 2014.
“The existing bridge was post-tensioned concrete, so they came in with some specialist munchers to break down and remove it,” explains BBMM structures portfolio manager Mangat Bansal. Forshaw reduced the bridge to 1,500 tonnes of hard stone that was then re-used for the site compound, reducing costs for landfill.
Starting with this demolition phase, BBMM developed a visual programming system, where the entire project was laid out on the walls of a room in the site office for all to see.
“It wasn’t a case of telling [our subcontractors] – it was with their input that they were able to help devise the programme”
Mangat Bansal, BBMM
“The scheme programme was on the walls of this room and we used to have a lean programming weekly meeting, with all the contractors attending, and we’d go through the programme to see who was doing what where, where the interfaces were and how people could help each other,” Mr Bansal says. “This meant all the contractors were able to buy into what the site objectives were and what we were trying to achieve.”
Critical events such as the weekend closures for the demolition and the eventual placement of the new bridge deck saw separate meetings held to discuss potential risks and go over the planned sequence in detail, with an hour-by-hour programme developed. “It wasn’t a case of telling [our subcontractors] – it was with their input that they were able to help devise the programme,” Mr Bansal says.
‘You wouldn’t believe it’
Once the old bridge was removed, attention turned to constructing and installing the new structure.
To minimise the amount of possession time needed, the team decided to build the bridge in a field adjacent to the M56, before lifting the deck into place over one weekend closure. With 120,000 vehicles passing along this stretch of the M56 each day, this weekend was crucial – especially with Manchester Airport so close by.
The team built the two-span bridge structure on temporary supports, before it was lifted onto a self-propelled modular transport system (SBMT) supplied by subcontractor Mammoet – a piece of machinery Mr Bansal describes as a “massive boy’s toy”.
“It can be moved very, very accurately. You wouldn’t believe a deck of that dimension could be moved millimetres by this piece of kit”
Mangat Bansal, BBMM
The SBMT is effectively a vehicle with a set of hydraulically operated axles, driven by remote control. “Each of the axles are individually operated, so the bridge it was carrying could do pirouettes on the motorway if you wanted it to,” Mr Bansal says. “You can move it any direction you want and there’s a vertical adjustment as well. It can be moved very, very accurately. You wouldn’t believe a deck of that dimension could be moved millimetres by this piece of kit.”
The bridge deck itself measured approximately 90 m long by 15 m wide and weighed 1,500 tonnes. The substructure was built in situ by Cleveland Bridge, with a clearance of 75 mm all around when the new deck was placed.
“Because of the tight timescale and the lead-in periods for procuring and fabricating the structural steelwork, we engaged with Cleveland Bridge very early on in the design process to keep them involved in the design so it would suit their fabrication techniques,” Mr Bansal says. “We were able to place an order early for them to fabricate, enabling us to take delivery of the steel earlier than if we had waited for everything else to be complete.”
Mammoet lifted the bridge from its temporary supports to a height of 10 m before carefully driving it down the motorway slip road and into position.
Balfour Beatty Mott MacDonald JV_Thorley Bridge M56 2
The final manoeuvre saw the team turn the deck 90 degrees to align it over its permanent supports, lowering it over temporary bearings. The jacks were then removed and once the bridge settled in its final position the SBMT could move away and the bridge placed on its permanent bearings.
“The whole operation took, in terms of purely driving it down, from 8am to 9pm,” Mr Bansal says. “The rest of the time was taken up with preparing the motorway, removing various bits of motorway infrastructure and signage, to give us a clear path to its final location. Once the bridge was in its final position, we then had to remove all the load-spreading mats and all the temporary stone that had been placed. It took us the best part of 24 hours to do all that.”
“We had more temporary works concrete to allow the deck to be built in the field, than there was permanent concrete [in the finished bridge]”
Mangat Bansal, BBMM
The move itself took place in February last year, on the same day as a Manchester City home game against Newcastle, ensuring lots of travelling fans would be on the road.
“We enlisted their communication channels to let their fans know the motorway was closed so they could plan their journeys in advance,” Mr Bansal says. “We used a similar strategy with Manchester Airport, because they communicate with passengers through the airlines, so we were able to work closely with them too and use their channels.”
Chevron carried out traffic management with Highways England, taking care of the 120,000 vehicles that would have normally used the motorway on each day of the closure.
The team also carried out some early value engineering to divert a number of utilities. The old bridge contained a number of services in its deck which would have to be moved and maintained throughout the project.
BBMM subcontracted SW Drilling, a specialist directional drilling contractor, to install ducts underneath the motorway instead, providing a new home for the utilities. Local reinforced concrete specialist Kilmartin was also brought in to carry out all of the concrete works and formwork.
“We had a huge amount of concrete works to be done, not just for permanent works but also for temporary works where the bridge deck was being built,” Mr Bansal says. “In fact, we had more temporary works concrete to allow the deck to be built in the field than there was permanent concrete [in the finished bridge].”
The motorway was re-opened at around 9pm on Sunday evening – 10 hours before it was due to be handed over. BBMM has since taken the lessons learned to other projects in Area 10, especially around visual programming and sequencing.
“Not all of our contractors had worked on such an in-your-face visual system with a room dedicated to managing interfaces, allowing us to identify things that would happen six weeks in advance,” Mr Bansal says.
“We now regularly use such techniques on our major projects. And we’ve maintained the good relationships we built with Mammoet and Kilmartin, so we were able to take them onto a not-too-dissimilar project where we had a significant amount of concrete works and needed to move a bridge deck.”
Early supply chain engagement and continuous collaboration combined to install this M56 bridge – satisfying Highways England’s aims of improving safety and reducing congestion with minimal fuss.
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