A 93m-long bridge crossing the White Cart Water is the centrepiece of the Amids South project, which aims to boost the local economy by improving transport links between an industrial area, Paisley town centre and Glasgow Airport.

The Advanced Manufacturing Innovation District Scotland (Amids) – a collaborative project led by Renfrewshire Council and supported by the Scottish Government and Scottish Enterprise – aims to attract businesses in the manufacturing sector to locate at its dedicated 52-hectare (520,000m2) site between Renfrew and Inchinnan.

It is already home to the National Manufacturing Institute Scotland, the Medicines Manufacturing Innovation Centre, various multinational manufacturers, as well as research and skills centres.

The site is still in the development phase, projected to be completed in 2034. Acknowledging that Amids’ connectivity to nearby towns is key to its success, the council has developed several infrastructure projects to enhance it in recent years.

One was the Renfrew Bridge (NCE, September 2024) – funded by the Glasgow City Deal – which opened last May. This project has improved access to Amids for those travelling from Yoker or other areas on the Western bank of River Clyde. The Amids South project, currently underway, focuses on enhancing the manufacturing district’s connectivity with the nearby town of Paisley and Glasgow Airport, through the introduction of new road and active travel infrastructure.

The £59M project involves the construction of a 93m-long, tied-arch bridge at Paisley Harbour crossing the White Cart Water; 1.7km of road infrastructure – upgrades to existing roads and a new gateway from Paisley town centre to Amids and Glasgow Airport, and 550m of new road to serve the new Paisley Grammar School Community Campus.

It will also introduce new active travel routes, including the Gallowhill Link which will use a former railway underpass to provide crossing under Renfrew Road from Gallowhill for the new school and the bridge.

Renfrewshire Council appointed Amey as the principal designer, while Ramboll is responsible for the structures and geotech design. Farrans was awarded the main construction contract last August and started working on site in October.

With the project scheduled to be completed in 2028, the project team is working on a tight deadline. Poor ground conditions, site limitations and underground assets have been construction hurdles, but a change to the bridge’s design and construction methodology are offering programme efficiencies.

Benefits

The majority of the Amids South funding, £38.8M, originates from the UK Government Levelling Up Fund. Renfrewshire Council allocated £18.8M for the project, while £1.5M was provided by Transport Scotland for the Gallowhill Link.

Amids South is one of the largest Levelling Up Fund projects, a testament to the potential benefits it could offer to the local community and economy.

Renfrewshire council senior manager for infrastructure and transportation John Wallace says the new roads will reduce journey times for motorists between Paisley town centre (Incle St/Weir St junction) and Sanderling Roundabout (Glasgow Airport), in addition to a 20-minute reduction for pedestrians between Gallowhill and Inchinnan Road. It is also expected to reduce congestion in the town centre.

Wallace adds that the project will encourage modal shift as the new active travel routes will be linked to existing ones. It has been estimated that the project will cut carbon emissions from vehicles by more than 10,810t CO2e over the 60-year assessment period.

“We’ve actually projected to reduce whole life carbon over the next 60 years,” says Amey’s head of practice (structures and geotechnics) Kieran O’Connor. “It’s a good example of a scheme where you can spend carbon wisely in order to provide longer term benefits.”

Another long-term benefit of the project could be a boost to the local economy, with its business case stating that it could lead to an additional £136M of private sector investment.

“This project will also improve opportunities for the local communities, providing them with better access to job opportunities,” Wallace emphasises, adding that many of these opportunities could be local. The council hopes that the improved connectivity of Amids – especially in relation to the airport – could help existing companies grow and attract new businesses to the industrial district.

The project is already benefitting the local economy. Two-thirds (66%) of the 201 material orders that had been placed by Farrans by the time NCE went to press were to suppliers based less than 20 miles (32km) from the site, while 45% of the subcontracts were awarded to subcontractors based within the same radius.

Amids is a collaborative project led by Renfrewshire Council and supported by the Scottish Government and Scottish Enterprise to attract businesses in the manufacturing sector to locate at its dedicated 52-hectare site between Renfrew and Inchinnan

Bridge design

“We [Amey] were initially awarded the contract in October 2019. It was funded by the Glasgow City Deal,” says Gordon MacDonald, project director of Amids South at Amey. “At the time there was no given layout for the scheme. The council wanted a gateway route from Paisley Town Centre, out towards the Glasgow airport, and to open up industrial land for regeneration.”

The Covid-19 pandemic caused delays and funding challenges. The project was reinvigorated in May 2021, after the council secured funding from the Levelling Up fund.

O’Connor says 28 route options were assessed by Amey in the early days. “One of the reasons we chose the current route is a reduced risk from ground conditions and contaminated land,” he says. “In terms of the bridge itself, the ground conditions are quite poor.”

David Buchanan, senior project manager for Amids South at Farrans, says: “On the approaches to the bridge we are finding that below 7-8m deep the ground is suitable, but above that good fill is sandwiched between layers of made ground. It’s an old industrial area and the ground has been through years of build-up; so it’s not ideal, but we are working with the design team to minimise the impact.”

This has influenced the bridge design. “Having a tied arch essentially removes the need for the thrust from the arch to go into the ground, and instead it’s taken within the bridge itself. So that meant that the bridge could be supported on concrete piles down to bedrock,” says O’Connor.

MacDonald adds that the high flood levels in the White Cart Water also influenced the bridge design, with the design team opting not to have permanent piers in the water.

“This increased the span and ruled out a lot of the more typical beam and slab type arrangements”, says O’Connor. “The client preferred not to have a mast and cable type arrangement and so a tied arch solution was deemed to provide optimal efficiency and aesthetics. A key benefit is that the deck is quite slender, reducing the extent of earthworks needed on the approaches.”

We’ve actually projected to reduce whole life carbon over the next 60 years. It’s a good example of a scheme where you can spend carbon wisely in order to provide longer term benefits

The bridge’s span reduced from 120m to 93m during the design phase. O’Connor explains that was achieved through the tightening up of the alignment by following the National Road Development Guides as opposed to Design Manual for Roads and Bridges. It was agreed with Renfrewshire Council to better fit the local environment while optimising the bridge layout.

“It reduced embodied carbon by about 1700t and reduced the cost quite substantially,” O’Connor highlights.

Once the tied arch concept was decided on, the team opted to have inclined arches and to be braced at the top. “It provided more stiffness and stability, resulting in reduced steel tonnage”, O’Connor says.

The arch is made of steel grade 355, while the deck will be a C40/50 concrete with high ground granulated blast furnace slag (ggbs) cement replacement. “Ggbs offers quite a lot of advantages for bridges, because it’s more durable and it helps to control cracks,” says O’Connor.

The bridge will be 20.8m wide, with 7.8m dedicated to the carriageway and 3.25m to active travel paths on each side. A 2m high, curved parapet has been designed on the edges of the bridge which is inclined into the active travel path.

The clearance above White Cart Water is 6.6m, with the soffit designed to be above 1 in 200-year flood event with allowance for climate change. The bridge has a design life of 120 years.

The project will enhance active travel in the area through the creation of new routes with links to existing ones

Construction methodology

“The client had a concept for the bridge installation at tender stage. It was basically to build a 100m-long cradle where the bridge would have been supported, and the bridge would have been launched into place from there,” Buchanan says.

He explains that this would have resulted to the bridge being over-engineered and required the need for temporary works in the river, so Farrans proposed a different construction methodology. It involves elements fabricated offsite by Belgian steel fabricator Victor Buyck, the bridge fabricated on site and launched using SPMTs and cranes on either side of the river

The contractor worked with Victor Buyck on various projects over the past decade, including the Govan-Patrick footbridge in Glasgow – which opened in September 2024 – and the Gull Wing bridge (NCE, November 2022) in Lowestoft, which opened in November of the same year.

The bridge elements will arrive from Belgium by road. A total of 35 lorries will be used to transport the bridge elements which include eight main girders, 22 cross beams, two end cross beams, four knuckles, eight bow strings, four cross bracings, and three sets of 21 longitudinal beams.

Buchanan says: “We’re trying to do as much as possible in a controlled environment at the fabrication workshop in Belgium. The majority of welding, painting and checks will be completed there prior to transport. The plan is for the bridge to leave the workshop defect free.”

“We’ll stitch it all together on site and do the final welding and painting in Scotland,” he says, adding that a dedicated fabrication area will be established on the south embankment. When the bridge is ready to be installed, the team will use SPMTs and a crane located on the north embankment to lift it into place.”

The total weight of the bridge will be 790t, while the total weight of the temporary works structures to assist in the fabrication and launch is estimated to be around 150t.

“The biggest challenge we have between now and delivery of the bridge sections is the execution of the temporary works for the final build and launch,” says Buchanan. At present the team are  working on a platform for the crane on the north embankment and others on the south embankment for the fabrication and launch area.

“We are due to start receiving sections of the bridge during the week commencing 29 June. Six weeks after that, Victor Buyck will send the fabrication team to the site, and the bridge will undergo final assembly, welding, painting and the installation of any temporary works to the structure prior to the launch, which is planned for Spring 2027,” Buchanan adds.

Progress and other assets

While the bridge elements are being fabricated, ground engineering works for the bridge construction have been underway.

Buchanan says ground improvements involve the installation of around 1,500 Controlled Modulus Columns and Bi-Modulus Columns on each embankment. These works were carried out by Menard UK in February and March. “When the road will opens in 2028, the embankments will be monitored for 24 months for settlement,” says Buchanan.

In May, Quinn Piling began installing 20-26mm-long, 900mm-diameter rotary bored piles with a 6m rock socket for the construction of the bridge abutments. It will install 20 piles for each abutment.

Piling works are required in other parts of the project. 600mm diameter, 12m-long rotary bored piles have been installed to bridge a Scottish Water 2.5m-diameter Victorian sewer, to protect it from the construction of the road on top of it.

The road infrastructure to be constructed as part of the project will boost the connectivity of Amids and provide better access to job opportunities for the local population

In addition, a 340m-long contiguous pile retaining wall will be constructed alongside the White Cart Water, just south of the bridge.

MacDonald says the construction of this wall was essential because the existing retaining wall and part of the riverbank couldn’t pass assessment, given a lack of records, to accommodate the new alignment with widened active travel provision.

“We had to effectively put another wall in front of it. So it’s a bored pile wall with a cantilever reinforced concrete section to sit on top, to raise the height for cyclist protection adjacent to the river,” he explains.

Buchanan characterises this job as one of the project’s most challenging because of the site limitations and the extensive temporary works required to execute the works.

One section of the project nearing completion is the section of carriageway linking the existing road network with the newly constructed Paisley Grammer School which is due to open to pupils in August 2026. “Delivering this section of works was a priority for the client. We have completed the earthworks on the section and surfacing works to the carriageway are due to start in May, with completion on time for the school opening as planned,” says Buchanan.

He says that site works are progressing as planned and is optimistic that the project will be delivered on time in 2028.

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