Client
Highways England
Value
£6.16 million
Sectors & Services
Highway Structures Concrete Repair Corrosion Control Cleaning & Preparation Projects Projects
Birmingham’s Gravelly Hill Interchange, universally known as Spaghetti Junction, is one of the most complex and heavily trafficked motorway interchanges in the UK. The works focused on 12 cross-head structures supporting the A38 Aston Expressway, a critical arterial route leading directly from the interchange into the city.
Delivered within Highways England’s Area 9 framework, CRL was appointed as principal subcontractor to Kier Highways to address progressive concrete deterioration and long-term corrosion risk. The project was essential to safeguard structural integrity, improve durability and maintain network reliability. The expanded scope resulted in an 18-month programme and a final project value of £6.2 million.
Services undertaken
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Resonance testing of concrete surfaces to bent structures
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Hydro-demolition and surface preparation
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Installation of Impressed Current Cathodic Protection system
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Steel continuity testing and electrical dis-continuity checks
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Installation of ribbon anodes and discrete anodes
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Sprayed concrete application to beams
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Ongoing monitoring by CP Level 4 Engineer
CRL delivered a technically demanding package of works combining advanced investigation, structural concrete repairs and permanent corrosion mitigation. The scope commenced with resonance testing of all concrete surfaces to the bent structures, allowing defective and delaminated areas to be accurately identified prior to intervention. Multi-phased concrete repairs were then undertaken to the cross-beams and the tops of the supporting columns. These repairs were tightly controlled in both size and location to meet the client’s strict engineering requirements, extending the programme but ensuring full technical compliance.
Access was a major consideration due to the complex geometry of the interchange and the proximity of live carriageways. High-level access scaffolding was designed and installed to exacting safety standards, fully boarded and enclosed with timber and Monarflex sheeting. This provided safe working platforms for a large workforce while protecting other stakeholders using adjacent roads and access routes.
Following concrete repairs and surface preparation, CRL installed a comprehensive Impressed Current Cathodic Protection system in accordance with the design drawings. This included the installation of 156 Ag/AgCl/0.5M KCl reference electrodes, 188 negative steel connections, 188 positive connections welded to the anode ribbon and approximately 1,790 metres of ribbon anode pinned to the prepared concrete surfaces. Where ribbon anodes could not be installed due to electrical duct obstructions, 35 additional discrete anodes of an alternative design were incorporated. Sprayed concrete was applied to beams, steel beam painting and welding works were completed, and a new AC electrical power supply circuit was installed to power the ICCP system. Extensive system testing, including half-cell testing, continuity and dis-continuity checks, was carried out throughout, reflecting CRL’s disciplined and technically assured approach to complex structural repairs UK schemes.
“Well done to the site team; a great result and delivered on time.”
Colin Jackson | Delivery Manager | Highways England
Long-term durability and asset preservation were central to the Spaghetti Junction works. High-quality surface preparation using hydro-demolition ensured effective bonding of repair materials and reliable performance of the ICCP system. The installed impressed current cathodic protection provides active, long-term corrosion control to embedded reinforcement, significantly reducing the risk of future concrete deterioration. Comprehensive testing and commissioning confirmed system performance prior to energisation.
The installation of a dedicated AC power supply and Transformer Rectifier Units allows the ICCP system to be continuously monitored and adjusted. Ongoing oversight by CRL’s CP Level 4 Engineer ensures the system operates to its full potential and remains aligned with client expectations. These measures collectively reduce future maintenance demands, enhance structural resilience and extend the service life of a nationally significant asset, supporting effective long-term asset management.
