M6/M42 Interchange

Protective Coating and Structural Maintenance Works on the M6/M42 Interchange Bridge

The M6 Junction 4A to the M42 is a key interchange within the West Midlands motorway network, providing a vital link between the M6, M42, and routes serving the North West, South East, and Birmingham Airport. As one of the busiest sections of the UK’s strategic road network, it handles over 150,000 vehicles daily. Its strategic importance makes it a critical corridor for regional and national traffic, freight movement, and access to major transport hubs.

CRL, on behalf of National Highways, is delivering essential maintenance on the bridge linking the M6 Junction 4A to the M42. The project aims to safeguard the bridge’s long-term structural integrity and reduce the need for future interventions.

Ahead of works, an ecological survey was completed to ensure compliance with environmental regulations, including checks for bats. Given the bridge’s location over one of the UK’s busiest motorway sections and near the HS2 corridor, early coordination with stakeholders including Road Space Booking and traffic management teams, was essential. To minimise disruption to over 150,000 daily vehicles, all works are being carried out at night.

The scope of works involves the complete removal of existing paint coatings and surface oxidisation from approximately 3,000 m² of structural steelwork. Following this, the steel is prepared to SA 2.5 standard, ensuring a clean, bright metal surface suitable for the application of high-performance coatings. Once prepared, the steel is treated with a robust five-coat protective system designed to prevent corrosion and extend the lifespan of the structure. This system includes the application of a corrosion-inhibiting primer, followed by a two-pack epoxy intermediate coat, and finished with a durable aliphatic polyurethane topcoat. Together, these treatments provide long-term protection in a challenging and high-traffic environment.

A major challenge was safely removing the old coatings without disrupting live traffic or breaching environmental controls. This was overcome using vacuum blasting, which allows for localised containment and minimises dust and debris release.

The project is being led by CRL’s Technical Manager Chris Hinton, with site coordination by Dan Foxhall and James Lewis. Their work ensures smooth delivery, strict environmental compliance, and strong supply chain management.

Works are set to complete by the end of September. In parallel, ECI-led concrete repairs on the same structure, managed by Will Sinnott, are planned for next year.

This project showcases CRL’s 70 years of infrastructure expertise and its commitment to maintaining the UK’s strategic road network efficiently and sustainably.