A30 – Chiverton to Carland Cross
A30 – Chiverton to Carland Cross
Client: National Highways (formerly Highways England)
Main contractor: Costain/Jacobs Partnership
Bridge contractor: Keltbray
Value: £330million
The A30 Chiverton to Carland Cross scheme upgraded 8.7 miles of single carriageway to a 70mph dual carriageway in Cornwall, requiring 14 new structures, including overbridges, underbridges, precast BEBO arches, and over 33 culverts. Wentworth supported both Costain and Keltbray throughout the three-year construction period, developing temporary works solutions that enabled phased construction while maintaining traffic flow on this busy trunk road. Our work bridged the interface between multiple contractors, subcontractors, and permanent works designers across geographically dispersed sites.
8.7
miles of new dual carriageway alongside existing A30
14
bridge structures provided with temporary support systems during construction
32m
span bridge built 5m from operational 1970s bridge
Our Role
Our RoleWe provided comprehensive temporary works and construction engineering services to both Costain and Keltbray from early design stages through construction completion.
Our scope included temporary support systems for 14 bridge structures during construction, geotechnical design for slope stability and crane platforms, lifting point verification for multiple bridge beams, demolition engineering for an existing three-span bridge at Tolgroggan, and development of accelerated rebar stability solutions for bridge abutments. We coordinated construction sequences across multiple sites, ensuring solutions met the requirements of contractors, local authorities, and permanent works designers.
Our scope included temporary support systems for 14 bridge structures during construction, geotechnical design for slope stability and crane platforms, lifting point verification for multiple bridge beams, demolition engineering for an existing three-span bridge at Tolgroggan, and development of accelerated rebar stability solutions for bridge abutments. We coordinated construction sequences across multiple sites, ensuring solutions met the requirements of contractors, local authorities, and permanent works designers.
Capabilities
Capabilities- Bridges & Highways
- Demolition
- Geotechnics
- Structural Engineering
- Construction Method Engineering
- Temporary Works,
- 3D Modelling and Detailing
- Heavy Lift & Logistics
Constructing 32m bridge 5m from existing structure
Constructing 32m bridge 5m from existing structureBuilding a new 32 metre span bridge just 5 metres from an operational 1970s bridge created severe space constraints during abutment construction. Traditional approaches would either disrupt the A30 or risk damaging the existing structure carrying live traffic.
We developed construction sequences with efficient detailing that maximised the limited working space. Our temporary works design specified constraints on plant movements, excavation sequencing, and formwork installation that prevented interference with the operational bridge while enabling full construction access for Keltbray's operations.
This enabled Keltbray to construct the complete bridge abutment without traffic disruption or modification to the existing bridge, maintaining programme certainty on this time-critical trunk road upgrade.
We developed construction sequences with efficient detailing that maximised the limited working space. Our temporary works design specified constraints on plant movements, excavation sequencing, and formwork installation that prevented interference with the operational bridge while enabling full construction access for Keltbray's operations.
This enabled Keltbray to construct the complete bridge abutment without traffic disruption or modification to the existing bridge, maintaining programme certainty on this time-critical trunk road upgrade.
Coordinating multiple sites' geotechnical solutions
Coordinating multiple sites' geotechnical solutionsThe 8.7 mile project corridor had varying ground conditions at each of the 14 bridge locations, from large excavations requiring slope stability analysis to diverse foundation requirements for temporary crane platforms. Each site demanded tailored geotechnical solutions, but inconsistent approaches would have created inefficiency and increased risk for Costain and Keltbray working across geographically separated locations.
We conducted detailed slope stability assessments for large excavations and designed foundation systems for temporary structures and crane working platforms tailored to local ground conditions at each site. Our geotechnical team developed standardised assessment methodologies that could be rapidly deployed across multiple locations, while still addressing site-specific constraints and providing CAT 3 verification for critical temporary works.
This provided Costain and Keltbray with construction certainty across all sites, enabling parallel working on multiple bridge locations and maintaining the compressed construction programme for this strategic infrastructure project.
We conducted detailed slope stability assessments for large excavations and designed foundation systems for temporary structures and crane working platforms tailored to local ground conditions at each site. Our geotechnical team developed standardised assessment methodologies that could be rapidly deployed across multiple locations, while still addressing site-specific constraints and providing CAT 3 verification for critical temporary works.
This provided Costain and Keltbray with construction certainty across all sites, enabling parallel working on multiple bridge locations and maintaining the compressed construction programme for this strategic infrastructure project.
Faster bridge construction with innovative rebar
Faster bridge construction with innovative rebarTraditional bridge abutment construction would have needed extensive temporary formwork and multiple concrete pours, creating programme delays across the 14-structure scheme. Each abutment did require substantial reinforcement cages, but conventional methods would have meant slow, sequential construction, extending the overall programme and increasing traffic management duration on the busy A30.
We designed an innovative rebar stability method using lattice rebar towers that significantly accelerated abutment construction. This approach eliminated the need for extensive temporary formwork by creating self-supporting reinforcement structures. Our design validated the stability of the lattice towers during concrete placement, enabling faster construction cycles across multiple bridge locations.
Keltbray could construct abutments more rapidly across all 14 structures, compressing the construction programme and reducing traffic management requirements on this major Cornwall trunk road.
We designed an innovative rebar stability method using lattice rebar towers that significantly accelerated abutment construction. This approach eliminated the need for extensive temporary formwork by creating self-supporting reinforcement structures. Our design validated the stability of the lattice towers during concrete placement, enabling faster construction cycles across multiple bridge locations.
Keltbray could construct abutments more rapidly across all 14 structures, compressing the construction programme and reducing traffic management requirements on this major Cornwall trunk road.
Off-site prefabrication minimising disruption to A30
Off-site prefabrication minimising disruption to A30Costain and Keltbray needed to minimise disruption to the A30 while delivering 14 structures, but conventional in-situ construction approaches would have significantly impacted this vital Cornwall trunk road.
We developed temporary works solutions that specifically supported off-site manufacturing and modular assembly techniques. Our lifting point checks validated multiple bridge beams across various structures, and our temporary support schemes enabled rapid installation of prefabricated elements during short possession windows. The temporary works designs prioritised quick installation and removal to support night-time operations and minimise traffic impact.
Our technical solutions enabled extensive use of prefabrication and modern construction methods, reducing on-site construction time and keeping the A30 operational throughout the scheme delivery.
We developed temporary works solutions that specifically supported off-site manufacturing and modular assembly techniques. Our lifting point checks validated multiple bridge beams across various structures, and our temporary support schemes enabled rapid installation of prefabricated elements during short possession windows. The temporary works designs prioritised quick installation and removal to support night-time operations and minimise traffic impact.
Our technical solutions enabled extensive use of prefabrication and modern construction methods, reducing on-site construction time and keeping the A30 operational throughout the scheme delivery.
Outcomes
OutcomesThe A30 Chiverton to Carland Cross temporary works was nominated for the ICE South West Civil Engineering Awards 2025, recognising the innovative approaches that enabled the delivery of this complex multi-structure scheme. Our three-year engagement across 14 structures gave us a deep understanding of the programme constraints and enabled us to develop coordinated solutions that worked across multiple contractors and design interfaces.
Key results:
The A30 Chiverton to Carland Cross scheme opened in 2024, with Wentworth's construction engineering knowledge helping deliver predictable outcomes across one of Cornwall's most strategically important highway upgrades.
Key results:
- Award recognition: Temporary works nominated for ICE South West Civil Engineering Awards 2025 for innovation and delivery excellence
- Zero harm achieved: Contributed to 4.5 million hours worked without a reportable RIDDOR incident across the entire scheme
- Programme protection: Rebar stability innovations and prefabrication support compressed construction timescales across 14 structures
- Traffic maintained: Off-site manufacturing solutions minimised A30 disruption throughout construction
- Multi-party coordination: Bridged interfaces between Costain, Keltbray, local authorities, and permanent works designers
- Construction certainty: Geotechnical assessments and temporary works designs enabled parallel working across geographically dispersed sites
- Modern methods delivery: Lifting checks and temporary support schemes enabled extensive modularisation and prefabrication
The A30 Chiverton to Carland Cross scheme opened in 2024, with Wentworth's construction engineering knowledge helping deliver predictable outcomes across one of Cornwall's most strategically important highway upgrades.