Cutting congestion and carbon

The Cross Tay Link Road is the biggest infrastructure project ever undertaken by Perth & Kinross Council. As work on the new bridge and associated roads nears completion, BAM has achieved some significant savings in carbon output on the project.

The ‘Fair City’ of Perth, in the heartlands of Southern Scotland, was once the country’s capital. Nearby stands Scone Palace, where Scottish kings were crowned for centuries.

But Perth’s geographic position on the banks of the River Tay – which helped to establish its historic importance as a centre for trade and a crossroads for travellers – has also contributed to a very 21st century problem: traffic congestion.

To address the issue, Perth & Kinross Council set up the Perth Transport Futures Project: a programme of major infrastructure upgrades to improve the road network around the city. It will address the area’s long-term transport needs and promote economic growth, while tackling congestion and pollution.

The cornerstone of the Perth Transport Futures Project is the Cross Tay Link Road (CTLR), being delivered by BAM and due to be finished in 2025.

Motorists in Perth often face long queues, as the road network forces high volumes of traffic into the city centre. There are currently only two bridges across the River Tay, which cuts the city in half from north to south, so drivers cannot avoid using the congested city streets. The solution is an ambitious scheme – being delivered by BAM – that includes building a new three-span bridge over the Tay and creating a six kilometre stretch of carriageway to link the A9 and the A93 to Blairgowrie and the A94, just north of Scone.

The CTLR also involves realigning a two-kilometre stretch of dual carriageway on the A9 to facilitate access to the new river crossing.

The new road will unlock key development land and direct through traffic away from the city centre, reducing pollution and congestion, and creating a better experience for both visitors and local drivers.

BAM’s successful bid for the project included several important commitments that will benefit both the project and the local area. These included a package of community benefits and a major reduction in the scheme’s carbon footprint.

Central to this is an understanding of the environmental sensitivities of the location. So BAM has focused innovate methods to cut carbon, improve air quality and boost biodiversity throughout the lifecycle of the scheme.

The carbon challenge

Perth & Kinross Council set BAM the goal of reducing carbon by 30% compared with the original design for the scheme: but this target has already been exceeded by a big margin.

By October 2022 (around half way through the project) BAM had reduced carbon output by over 35,000 tonnes, through detailed design development and changes to construction methods: the equivalent of taking over 20,000 small cars off the road for a year.

For example, redesigning the river bridge and its back spans to make them shorter (by a total of some 32 metres) resulted in significant embodied carbon and cost savings, as less concrete and steel were needed for construction.

BAM focused on procuring as aggregates as locally as possible. And all the excavated earth from the project is being directly recycled to form features in the scheme such as road embankments, significantly reducing construction traffic on local roads.

By the time construction of the link roads and bridge is complete, further significant improvements in carbon emissions are expected. The Scottish Government now holds up the project’s approach to carbon saving as an example of best practice when it comes to sustainable procurement.

As Jillian Ferguson, Roads Infrastructure Manager at the Council, explains: “Reducing carbon output is a key deliverable for the project… as it will act as an enabler to help shift traffic out of the city centre and promote active travel options”.

Green bridge

One of the highlights of the scheme is a new green bridge spanning the link road at the Highfield Plantation on the Scone side of the river.

The green bridge has been designed for both pedestrians and animals: connecting existing footpaths through the woodlands. BAM is also creating a tree-lined avenue between Highfield and the A94 roundabout.

Natural solutions

Several sustainable drainage basins (SuDS) are being created alongside new roads, to manage storm water by mimicking natural drainage.

Between the realigned section of the A9 and the railway, the SuDS are being incorporated into a new, landscaped Park and Cycle area, dotted with trees and picnic benches. Towards Perth racecourse, another wetland area is also being created which will be a natural haven for wildlife.

The CTLR team is also actively involved in supporting a new 43,000 square metre community woodland just north of Perth, being created as part of the Denmarkfield Rewilding initiative.

First ground was broken on the site by a group of BAM employees, community volunteers and staff in December 2022, with the planting of over 600 indigenous trees and shrubs. By the end of 2023, another 4,200 trees and shrubs will be added to this tally by BAM’s landscaping contractor.

BAM is also planning to help the rewilding team create new community allotments and an orchard.

In total, BAM is planting over 100,000 trees to compensate for those removed to make way for the new road: an increase of over 100% in the area’s overall vegetation coverage.

Economic and social benefit

BAM has been working collaboratively with its supply chain partners, and actively engaging with communities and stakeholders to maximise local employment and skills development.

From ‘Meet the Contractor’ evenings to open events for potential local suppliers and contractors, BAM and the Council have organised a range of events to ensure that residents and nearby businesses are fully involved in the project.

For example, over 140 pupils from Blairgowrie High School took part in a bridge building challenge, facilitated by BAM, in Autumn 2022, with the aim of sparking interest in engineering and construction careers.

“The Cross Tay Link Road is an important part of delivering on our ambitions for Perth city and the wider region. On completion it will deliver major benefits for residents through reduced pollution and carbon output, and will allow is to make active travel and environmental improvements to the city centre to support residents and visitors alike.”

Councillor Murray Lyle, Leader of Perth & Kinross Council

Don’t just take our word for it…

The project’s approach to carbon reduction is being used as best practice by the Scottish Government Discover more

The Council’s website for the project features a stunning flythrough Watch the video

The editor of Scottish Construction Now visited the project to see how BAM is achieving remarkable carbon reductions Read the article

BAM worked with pupils from a local high school on a bridge building exercise to inspire the next generation of engineers See how they got on