The Redbridge Viaduct, part of the A35 Redbridge Causeway, connects Totton to Southampton and the M271. Constructed in the 1960s, it comprises multiple leaf piers, column beam bents, and cantilever crosshead piers, some founded in a tidal estuary. Over time, concrete deterioration and reinforcement corrosion threatened the viaduct’s structural integrity and ongoing traffic operations.
To address these issues, Hampshire County Council commissioned a refurbishment valued at £5.1 million, with Milestone Infrastructure Ltd as principal contractor, Atkins as designers, and Concrete Repairs Limited (CRL) as specialist subcontractor. The project, spanning March 2019 to January 2024, focused on targeted concrete repairs and installation of an Impressed Current Cathodic Protection (ICCP) system.
The aim was to extend the lifespan of this vital transport link, ensure safety, and avoid costly replacement, all while working within strict environmental constraints in a sensitive tidal estuary.
Services Undertaken
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Hydrodemolition of deteriorated concrete on tidal and non-tidal piers
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Sprayed concrete and reinstatement using Fosroc Renderoc DSR
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Installation of Impressed Current Cathodic Protection (ICCP) system with titanium mesh and discrete anodes
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Remote monitoring setup for corrosion protection
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Phased repair sequences (15–20 per pier) to accommodate tidal constraints
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Cantilever and enclosed scaffold systems for safe tidal access
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Health and safety management including PPE, risk assessments, dust control, and water safety
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Environmental mitigation including water containment and treatment of hydrodemolition runoff
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Early Contractor Involvement (ECI) for method and sequence optimisation
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Coordination with principal contractor and design teams for efficient delivery
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Quality assurance and monitoring of repair works
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Adaptation of protection system from ICCP to galvanic CP where electrical continuity issues arose
The Redbridge Viaduct refurbishment employed a carefully phased approach to maintain traffic flow, protect the environment, and ensure worker safety. Hydrodemolition was used extensively to remove deteriorated concrete, followed by reinstatement using sprayed concrete and specialist Fosroc Renderoc DSR in tidal zones. Repairs were carried out in up to 15–20 sequences per pier, scheduled to accommodate tidal cycles and environmental permit conditions, avoiding the need for propping or cofferdams.
An ICCP system was installed to prevent reinforcement corrosion, utilising titanium mesh, discrete anodes, and remote monitoring equipment for ongoing asset management. Access scaffolding was specifically engineered for tidal operations, including cantilever scaffold systems and enclosed platforms to ensure safe, ergonomic working conditions.
CRL coordinated closely with Milestone and Atkins through Early Contractor Involvement, allowing continuous refinement of methods, sequencing, and environmental mitigation strategies. Health and safety protocols were rigorous, including PPE compliance, dust control, water containment systems, and thorough risk assessments for work at height and over water. Collaborative planning enabled efficient delivery, cost-effective solutions, and minimal disruption to traffic and the surrounding sensitive habitat.
Long-term protection measures ensure the Redbridge Viaduct now remains structurally sound and low-maintenance. The ICCP system actively prevents corrosion of steel reinforcement, while the high-performance concrete repairs have restored the structural integrity and durability. Careful surface preparation and the use of specialised materials minimise water ingress and deterioration in tidal zones. Environmental safeguards, including water containment and treatment during hydrodemolition, reduced ecological impact while supporting sustainability.
The project’s phased approach, combined with remote monitoring of the corrosion protection system, will enhance resilience, extend the viaduct’s service life, and reduce the need for future maintenance.
These measures provide a robust solution for structural repairs in the UK, protecting critical marine-based infrastructure and demonstrating effective asset management practices.
