Connecting communities

BAM has delivered a spectacular pedestrian and cycling bridge over the M8 motorway in the heart of Glasgow. The weathering steel structure is key to the regeneration of the Sighthill area: forming a new link to between the communities and the city centre.

Some £250 million is being invested in the Sighthill area of Glasgow, in the UK’s largest urban regeneration programme outside London. Although it is technically only a few hundred metres from the vibrant city centre, the sprawling residential area has been largely cut off from shopping, cultural and transport links since Glasgow was effectively sliced in half by the building of the M8.

The troubled high-rise blocks built alongside the motorway in Sighthill in the 1960s have gone: to be gradually replaced by over 1,000 new houses and apartments, as well as landscaped green areas, a new school and, vitally, a stunning new bridge over the M8 motorway for pedestrians and cyclists.

BAM successfully delivered this new Scottish landmark using cutting-edge engineering techniques that also minimised disruption for drivers and made highly efficient use of raw materials.

The main, 58metre span of the bridge is made of Cor-Ten steel, which weathers naturally and doesn’t require painting, minimising maintenance costs. It also reflects the industrial heritage of the wider area and echoes the front of the nearby St. Martin’s Primary School. The bridge’s curved hourglass form starkly contrasts the slab-sided concrete bridges that criss-cross the UK’s motorway network, providing a memorable landmark for drivers. The organic shape is enhanced by extensive planting along its whole length that extends down the curved approaches on both sides, so it’s hard to see where the bridge itself actually begins and ends.

Smart move

Traditionally, motorway bridges are constructed on site. This often entails long road closures, diversions and significant delays and disruption. But the Sighthill Bridge was different. The main span was fabricated off site in 17 steel sections, which were then welded together at a temporary assembly location.

The BAM team then only had one opportunity to get the 2,420 tonne structure in place. This involved meticulous planning and a range of temporary works to protect the road and surrounding assets, including a major pipeline under the carriageway that transports five million gallons of water a day.

The M8 is Scotland’s busiest road, so it was vital to keep traffic disruption to a minimum during its installation. To facilitate the installation, the M8 was closed overnight for just 14 hours. On the Saturday evening, BAM and specialists Mammoet drove the main span down the motorway to its final location. It was then pirouetted into place using two huge specialist rigs and gradually lowered onto the abutments before being jacked down into its final position.

Despite the huge complexities and the pressure to reopen the motorway for safe travel, the BAM/Mammoet team completed the installation three and a half hours ahead of schedule, with no accidents or incidents.

Pioneering 3D printing

With the main structure in place, the team could focus on completing the approaches to the bridge on both sides, particularly the plaza on the north side. BAM was the first contractor in Scotland to use 3D concrete printing, for the staircase accessing the bridge: believed to be the UK’s largest printed concrete construction to date.

Printing the staircase components made it much easier to create precise, intricate shapes for this unique structure. This approach also cuts waste by around 40% compared to traditional methods using moulds, keeping costs down and improving carbon efficiency.

Manufacturing the staircase in a highly controlled environment reduced the risks associated with on-site construction, include the challenges of the unpredictable Scottish weather. But the staircase is just as strong as if it had been poured on site.

Digital advantages

The use of digital tools, including 3D modelling and 4D planning, was essential in de-risking and quantifying the project. BAM modelled the entire project in house, from the tender stage which, among other things, helped the team to plan the extremely complex sequence of works, optimise the reuse of materials, reduce vehicle and haulage movements, control machines on site and manage logistics in collaboration with the supply chain.

This, in turn, helped to minimise the overall carbon footprint of the earthworks operations and reduce the project’s impact on the surrounding local road network.

Inspiring the next generation

In the local community, reactions to the new bridge have been overwhelmingly positive. But it’s not just about the practical benefits of a quicker and more enjoyable journey to the city centre.

In line with Glasgow’s commitment to long-lasting regeneration, the BAM project team actively provided opportunities for young people on the project. Local high-school students on summer placements, graduates and apprentices all worked on site: gaining a unique chance to experience this kind of ground-breaking engineering at first hand. BAM’s hope is that the project will inspire a whole new generation of young engineers.

“The on-going regeneration of Sighthill is one of the biggest projects of its kind on these islands – and the completion of this remarkable bridge is a real landmark in that journey. It signals the reconnection of Sighthill with not only the city centre but also neighbouring communities in North Glasgow.”

Councillor Susan Aitken, Leader of Glasgow City Council

Don’t just take our word for it…

Andrew McKibbin from Glasgow City Council, who’s been the Project Manager for the bridge since 2016, explains the unique nature of its design Watch the video

Kevin McKenna, a journalist with The Herald newspaper, grew up in Sighthill and tells the story of how the new bridge symbolises a true regeneration Read the full article

Watch a time-lapse video of the 14-hour installation as the bridge is swung into place over the M8 motorway Click to view the film