Future of Roads  |  Heads of the Valleys

Finding solutions

Property and environmental constraints posed design and construction challenges for the latest upgrade on the Heads of the Valleys road in south Wales. Nick Barrett reports.

Dualling the 17.3km stretch of the A465 Heads of the Valleys road between Dowlais Top and Hirwaun is the biggest road infrastructure project ever commissioned by the Welsh Government. Its estimated cost is £590M.

The project could also be considered one of the most challenging on the overall scheme to upgrade 40km of the A465 between Hirwaun and Abergavenny. This is due to the extensive environmental mitigation measures that had to be planned and executed.

The Heads of the Valleys road connecting communities between Abergavenny and Neath was originally constructed in the early 1960s. It is recognised by the Welsh Government as a strategically important national route. The road provides a key link to the Midlands, south west Wales and is an alternative to the parallel M4 route.

The A465 runs through areas renowned for their rich industrial heritage and stunning landscapes. But these are also among the most economically deprived areas in Wales, as there is high unemployment and a lack of private investment.

One reason they are unattractive to private investors is thought to be poor transport connections and the A465 was seen as inadequate for modern traffic volumes.

The Welsh Government believes that an upgraded Heads of the Valleys road will drive investment in the area by improving accessibility. The overall Heads of the Valleys road upgrade project – estimated to cost £1bn – was divided into six sections, with construction of the first between Tredegar and Dowlais Top starting in March 2002 after approval was granted following a public inquiry in 1999.

One of the final tasks is to upgrade sections five and six between Dowlais Top, Merthyr Tydfil and Hirwaun to dual carriageway. 

As well as the dual carriageway there are six new grade-separated junctions, 6km of side roads and 14km of paths for walkers, cyclists and horses. Other structures include three steel truss footbridges, five precast underpasses, 13 single-span and three two-span concrete bridges, six single-span steel plate girder bridges with precast concrete decks, 28 retaining walls and 38 culverts. The work also includes 12 temporary water treatment plants to remove silt, along with 20 permanent attenuation ponds.

Future Valleys Construction (FCC Construcción) was awarded the design and construction contract for this section of the A465 project. The project team was mobilised in October 2020.

PROCUREMENT APPROACH

Completion of the work on sections five and six in 2025 will be followed by a 30-year maintenance period under an innovative procurement approach called the Mutual Investment Model (MIM) (NCE, April 2021). It is a development of the Scottish not-forprofit approach used on the £1bn 35km Aberdeen Western Peripheral Route.

Under the MIM approach, the Welsh Government entered into an MIM Agreement to procure this design, build, finance, maintain and operate scheme with special purpose vehicle (SPV) company Future Valleys Project Co.

“Challenges include piled retaining walls as close as 1m from domestic properties

The SPV is owned by three shareholders: FCC Concesiones which is part of the Spanish FCC Group; infrastructure investor and asset manager Meridiam; and the Development Bank of Wales which represents the Welsh Government. The SPV in turn employs Future Valleys Construction.

By using the MIM approach the Welsh Government has addressed one of the criticisms of previous ways of using private finance. This was that the public purse would have had no benefit from refinancing to get better terms after the risky construction phase is over and the less risky 30-year maintenance period starts.

Under MIM the Welsh Government has a financial stake of 15% in the project so will benefit from refinancing.

Welsh Government transport director Andy Falleyn says the MIM Agreement provides a right for the public sector to appoint a director to the board of the SPV and ensures the public sector’s interest is represented in the decision making process.

Environmental constraints have been a major challenge for the project

LOCATION ISSUES

Design and construction of sections five and six of the scheme have had to take account of location-specific constraints. The hilltop scheme crosses two valleys and includes sloping ground, with a 210m difference in height above sea level between Hirwaun in the west and Dowlais in the east.

Sections of this stretch of the A465 are close to homes, schools, a hospital and business premises and in areas with challenging ground conditions.

FCC Construcción construction director Mike Cummine says: “Challenges include piled retaining walls as close as 1m from domestic properties, using 1.2m to 1.8m diameter bored piles to depths up to 25m to create room for the new carriageway, and building 28 reinforced earth retaining walls to support carriageways up to 16m high. Ground conditions have been very varied and challenging from hard rock to soft glacial till.”

Old coal and ironstone mine workings are a risk and have had to be filled in with grout in places.

“Ground conditions have been very varied and challenging from hard rock to soft glacial till

Cummine says: “We are installing bored pile retaining walls to allow the road to be widened through Cefn Coed. 

The ground conditions are particularly difficult there due to its location above hard limestone rock.

“There are karst features in the limestone with mapped caves nearby. Any voids encountered must be checked for the presence of bats.”

The route skirts the edge of the Brecon Beacons National Park and goes through a site of Site of Special Scientific Interest and two sites that include Scheduled Ancient Monuments. This led to the adoption of a comprehensive programme of measures to protect the environment. They included creating or relocating 345,000m² of habitats for protected species such as Great Crested newts, dormice, bats and marsh fritillary butterflies. In the first six months of 2023 alone over 7,000 hours of ecological surveys were undertaken.

The extensive environmental measures also included installing 87 structures for bats, providing 15 mammal crossings within culverts and erecting 1.2km of fencing to protect lapwing habitats.

Apart from challenges related to location, Cummine says that changing weather patterns with ever more frequent extreme rainfall disrupt the traditional summer earthworks seasons. One of the biggest challenges faced by the team is the forest of utilities requiring diversion particularly where the existing A465 crosses the local highway.

ON SCHEDULE

Apart from these challenges, the Covid-19 pandemic caused some supply chain issues at the beginning of the project. But the contractor is confident that it will be delivered on schedule in summer 2025.

Half of the earthworks have been carried out with 1.2M.m³ of material already excavated. Construction has started on all but two of the 32 bridge structures, 10 of which have already been substantially completed.

The success of the scheme could set an example for future projects in terms of environmental mitigation and use of MIM. Another aspect of the project’s legacy will be its contribution to the local economy, as 58% of the supply chain expenditure is staying in Wales and 34% in the Valleys local area.