A391 Carluddon Highway Improvement

The Gateway to St Austell and the Eden Project

The A391 Carludden road was not equipped to support the influx of traffic to St Austell. This area of road also lacked the proper provisions for pedestrians, cyclists and horse riders. The road improvement and construction of the Technology Park has allowed for economic growth in the St Austell area through the development of redundant land, the building of new homes and creation of new jobs. The £12.3m improvement project combined innovation, creativity and social value resulting in the project receiving the CEEQUAL Excellent award.

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Promoting Green Infrastructure

Demonstrating innovation and community focused solutions

The old A391 was narrow and lacked proper provisions for pedestrians, cyclists or horse riders. Those who used the national cycle network, ‘Clay trails’, between Wheal Martyn and the Eden project were forced to cross a busy section of the road. This project presented the opportunity to provide proper provisions for pedestrians, create better transport links to St Austell, transform redundant land into sustainable travel routes and give pedestrians, cyclists and equestrians access to green spaces.

Cormac’s work on this project included the construction of a roundabout, 1.6km of new road, improvements to existing junctions, facilities and route improvements for pedestrians and a 3.7km cycle trail. This project also included constructing a narrow-waisted, arched, over bridge. The bridge was planted with low-growing willow to provide a natural and biodiverse wildlife corridor across the new section of road.

Challenges to the project came from the scheme being built on former China Clay industrial legacy land. This required innovative design solutions, complex engineering and the relocation of three live China Clay pipelines.

The Bridge

Innovative design partnerships

Cormac worked with CTS Bridges who designed the new 31m x 3.5m Tied Arch bowed steel truss cycle/bridle bridge which connected the beautiful ‘Clay Trails’ which scatter the area.

The bridge itself is formed from 500mm CHS with steel hollow section hangers and sub-frame. Rubber tiles were overlaid across the deck to ensure a safe and quiet pathway for horse riders. Steel uprights were used for the 1.8m high parapet, a top rail with stainless steel weld mesh and a 625mm solid steel toe board completed the rest of the bridge infrastructure.

The bridge was transported in one piece from Huddersfield to Cornwall under police escort for the last segment of the journey. CTS then planned and supervised the installation.


Reducing Cormac’s carbon footprint

Minimising import of off-site material is a key part of Cormac’s sustainability practices. Almost all of the 50,000m3 excavated subsoil and rock was processed on site for re-use as fill. Imported materials were from local ‘second source’ quarries and all on-site topsoil was reused. To further minimise waste the site team also used the aggregate produced from China Clay industry waste.

Ecologists were brought in during site clearance to protect species such as slow worms, bats and nesting birds. Colonies of rare Bryophytes, a species of plant, were translocated to local receptor sites to ensure their preservation.

Overall this sustainable approach reduced the carbon footprint of the scheme and the impact of construction traffic on the local community.

Community Engagement

Prioritising communication

Throughout the project Cormac used a variety of communication channels to keep residents informed and ensure there was a place for the community to have a voice. This included regular invitations for residents to meet with the project team on-site, letters to residents throughout the duration of the project, informal presentations at the site office and regularly updated progress on both the CORMAC and Cornwall Council websites.

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    million pound project value

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    kilometres of new road

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    China Clay pipelines relocated

  • We’re proud to have delivered this major infrastructure scheme. The quality of the work is testament to our own workforce, our subcontractors and to our supply chain.

    Chris Wood - Carluddon A391

    Cormac Infrastructure Commercial Manager

News (10)


Cormac began as a business with a remit to service all the civil engineering needs of Cornwall. As a consequence we have an extensive range of specialist skillsets, and can offer a true end-to-end service to our clients in Cornwall and beyond.

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