- Client: National Highways
- Sector: Infrastructure
- Value: £28.5m
- Location: North West
- Service: Civil Engineering
A joint venture on behalf of National Highways between AmeySRM, saw our team build a new bridge over the M56 in Cheshire.
National Highways recognised the need to replace the existing bridge, situated between junction 11 and 12, which provided a vital connection for people living and working on both sides of the motorway. The existing bridge was built in 1971 and was replaced by a 67m two-span concrete bridge, consisting of a single two-lane carriageway and combined footpath and cycleway. The old bridge remained open whilst the new bridge was constructed, and the final phase of the project will see the old bridge demolished.
Communities and communication at the heart of the project
The team were aware of the significant risk of disruption to local communities and at the outset, pledged to construct the new bridge with minimal customer impact, whilst delivering tangible benefits to the local community.
Building a bridge of this nature over a motorway would typically require months of closures and disruptions for the 100,000+ road users that travel along that section every day. That doesn’t include the thousands of residents who rely on the bridge to reach vital services, work or education.
The old bridge carries internet and water services to hundreds of thousands of residents in Cheshire and Merseyside, which will require diversion. To overcome this challenge, the team needed to deliver a creative engineering solution that would enable the new bridge to be installed in a more efficient and less disruptive way.
Equally as important was adopting an innovative approach to communications, embedding social value activity to improve engagement with a range of key stakeholders, from Manchester Airport Group and local MPs to parents on the school run, cyclists commuting to work, dog walkers and families doing their weekly shop.
Innovative solutions to maximise progress and minimise disruptions
Building the bridge over the motorway was considered too disruptive to road users, leaving only one solution to build the bridge offsite. It would then be moved into position during a single weekend. Constructing the bridge in this way meant that it could be built at the same time as the abutments and central reservation, reducing the programme of work by an astonishing 12 weeks. This would result in enhanced benefits to the road users with shorter roadworks, less disruption, and reduced costs.
Collaborative planning sessions were held between the technical designers and construction team to ensure all internal stakeholders were in support of the plan. This also included contributions from the National Highways Operations division which ensured that the design of the bridge would reduce disruption to customers during maintenance requirements in the future.
Taking advantage of the M56 closure presented an opportunity for extensive additional work to be carried out by third parties, including barrier and bridge joint repairs, drainage work, maintenance, surveying and bridge monitoring. This reduced the need for additional closures in the future and an overall benefit to road users.
Engineering excellence in action
Working closely with heavy lifting specialists Sarens Engineering, this carefully orchestrated bridge replacement involved jacking up and installing the new 1,200T bridge using Self-Propelled Modular Transporters (SPMTs).
To complete the task, Sarens deployed six CS450 jacking systems, 56 axle lines of K24ST SPMTs, and a BS610 bracing system. The equipment was delivered via road, with the SPMTs and some of the steelwork arriving in 26 trucks from the UK, while the jacking systems and remaining steelwork were sent via 14 trucks from Belgium and France.
With the equipment on the job site 12 days before the move was scheduled, the team began final preparations for the bridge replacement. The team dealt with a technically challenging 6% slope along the route from the compound, where the bridge was assembled, to its final location. This meant navigating up a 6% slope to the A533 road and then down a 6% slope onto the M56 motorway, with the bridge at installation height throughout.
A temporary ramp was installed the night before the transport operation and cleared away the night after. With the team and equipment ready, the motorway closed for 57 hours but opened a day early. The six crew members worked together to ensure that everything proceeded smoothly during the operation, right up to matching jacking speeds when jacking the bridge up three lines of support using the first-generation CS450 on the abutments and the second-generation CS450 at the pier.
Putting the community first
Taking lessons learnt from prior National Highways schemes, the team understood the need to ensure the community and road users were always informed and understood what was going on. They prioritised early engagement particularly ahead of and the during the closure.
A 3D visualisation and innovative animated diversion route map helped road users understand the need for the closure and the expected disruption to traffic. The team ran a colouring competition with the local primary school to create visuals that were used to raise awareness of the closures. They made sure key external stakeholders like Halton Council and Mersey Gateway were well informed and thus able to utilise more channels to communicate what was going on.
As part of our Strong Foundations grants for 2022, the team allocated £25k to eleven grassroot community projects local to the site. At the A533 topping out ceremony, official cheques were presented to several of those organisations, celebrating the community involvement as well as showing off some of the artwork made by a local primary school. The project team have supported mock interviews and career events at a number of local schools and colleges, furthering the positive impact with the community.
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