HS2 Reaches Key Milestone as Traffic Moves onto New A43 Bridge Near Brackley

Complex road realignment completed after carefully planned weekend closures, paving the way for high-speed railway construction beneath one of Northamptonshire's busiest roads.

HS2 has completed a major engineering milestone on the route between London and Birmingham after successfully transferring traffic onto a newly constructed bridge carrying the A43 near Brackley.

The operation, completed over two consecutive weekend closures, marks the beginning of the next phase of construction, allowing excavation to start beneath the dual carriageway so that the future high-speed railway can pass underneath without disrupting one of the region's most important transport corridors.

The A43 provides a vital strategic connection between the M40, M1, Oxford, Brackley and Northampton, while also serving Silverstone Circuit, making careful traffic management a critical element of the project.

Years of planning lead to weekend switch

The latest works are the culmination of a construction programme that began in 2023, when engineers created a temporary realignment of the A43 to establish sufficient space for construction of the permanent bridge structure.

Using a top-down construction methodology, contractors installed deep piled foundations before constructing the supporting piers and pile caps required for the bridge.

Seven large steel girders were subsequently lifted into position to support the 66-metre-long bridge deck, before completion of the carriageway and associated highway infrastructure.

Rather than closing the route completely, engineers adopted a phased approach that maintained traffic flow throughout construction. Each carriageway was diverted separately over successive weekends, allowing one direction of travel to remain operational while work progressed on the other.

The final stages were deliberately scheduled after the Formula One British Grand Prix at Silverstone to minimise disruption during one of the busiest periods on the local road network.

Railway excavation can now begin

With both carriageways now operating across the completed bridge, construction teams can begin excavating the railway cutting beneath the structure.

Luis Gonzalez, HS2 Ltd's Head of Delivery, said completing the traffic switch represented an important milestone for the project and thanked motorists for their patience during the planned closures.

He said the successful completion of the road realignment allows the project team to focus on constructing the railway beneath the A43 while keeping traffic moving above.

Collaboration across multiple delivery partners

The section of HS2 passing Brackley forms part of the approximately 80-kilometre central route being delivered by EKFB, the joint venture comprising Eiffage, Kier, Ferrovial Construction and BAM Nuttall.

Working alongside National Highways and Kier Transportation, the delivery team developed a construction sequence designed to minimise disruption while maintaining access along the busy strategic route.

National Highways said close collaboration, innovative traffic management and detailed planning had enabled the project to progress while reducing impacts on road users as far as possible.

Wider progress across the route

The A43 milestone forms part of wider progress being made across the central section of HS2.

Over the past six months, six road and bridge projects across Buckinghamshire and Northamptonshire have been completed and reopened to local traffic, including works on the A4421 Buckingham Road, Edgcott Road near Quainton and Oatleys Road, which now crosses the Turweston Green Bridge close to Brackley.

Across the entire HS2 programme, more than 500 bridge structures are being delivered, ranging from road overbridges and wildlife crossings to major motorway structures and the landmark Colne Valley Viaduct.

Delivering the next phase of HS2

The new high-speed railway is intended to improve connectivity between London, Birmingham and the Midlands while releasing capacity on the southern section of the existing West Coast Main Line for additional commuter and freight services.

Although significant progress continues to be made across the route, substantial construction work remains before the railway becomes operational.

HS2 Ltd Chief Executive Mark Wild is currently leading a comprehensive review of the programme aimed at improving delivery efficiency and ensuring the remaining sections of the railway are completed at the lowest reasonable cost while maintaining programme objectives.