National Highways Warns Time Is Running Out for Ageing Guildford A3 Bridges

£5 million repair programme aims to prevent long-term structural deterioration as major weekend closures begin.

A major bridge repair scheme on one of Surrey's busiest roads has entered a critical phase, with National Highways warning that delaying the work could have left part of the A3 facing severe restrictions within just a few years.

Engineers have begun extensive repairs to the Dennis Interchange bridges in Guildford, where decades of water ingress and winter road salt have caused steel reinforcement embedded within the concrete structure to corrode.

The deterioration has prompted a £5 million restoration project designed to extend the life of the dual carriageway and avoid more disruptive interventions in the future.

Weekend Closures Required

To allow the next phase of repairs to take place safely, the A3 southbound between the Dennis and Stoke interchanges will close from 9.00pm on Friday until 6.00am on Monday.

A second closure affecting the northbound carriageway will follow the following weekend, operating between 9.00pm on 17 July and 6.00am on 20 July.

The closures will enable contractors to carry out waterproofing and resurfacing works above the bridge while repairs continue beneath the carriageway.

Hidden Damage Beneath the Surface

According to National Highways, moisture penetrating the bridge deck has reached the steel reinforcement within the concrete support columns.

As the steel corrodes, it expands, causing the surrounding concrete to crack and break away, progressively weakening the structure if left untreated.

Project Manager Nick Axford said the intervention is intended to restore the bridge before more significant deterioration occurs.

"We're carrying out preventative repairs now to restore the structure to full strength and ensure it remains in service for many years."

Alongside repairing the bridge itself, engineers are improving the waterproofing of the carriageway to prevent future water penetration and slow the deterioration process.

Drivers Face Lengthy Diversions

During the closures, traffic will be diverted through Guildford town centre, with motorists advised to allow additional time for journeys.

National Highways acknowledged that the diversion is longer than drivers might expect, but says it has been selected for safety reasons.

Although some motorists may consider using the nearby A25, it has not been designated as the official diversion because a low railway bridge creates a risk of heavy goods vehicles becoming trapped.

Officials say any HGV becoming stuck beneath the bridge could create significant disruption and present operational challenges due to the lack of suitable turning space.

Investment to Protect a Key Route

The Dennis Interchange forms an important junction on the A3, linking Guildford with London, Portsmouth and the wider strategic road network.

National Highways expects the £5 million programme to be completed before the end of the year, safeguarding the ageing infrastructure and reducing the likelihood of more extensive repairs in the future.

The project also highlights the growing challenge facing infrastructure owners across the UK, where many bridges built decades ago are now reaching the stage where targeted investment is needed to preserve their long-term resilience and maintain reliable journeys for road users.