The construction of a bridge that will allow high speed trains to pass under the busy A43 near Brackley has taken a major step forward with the structure’s enormous steel beams lifted into position during a series of three weekend closures.

The A43 – which links Oxford, Brackley and Northampton – is a vital route, providing access to Silverstone and connections between the M40 and M1. It was reopened just before midnight on Saturday night after the last of three weekend road closures.

Preparation for the work began in 2023 when HS2 engineers, working closely with National Highways, realigned the road to create an ‘island’ between the two carriageways big enough for the construction of the new bridge deck.

Using a ‘top-down’ approach, they sank 52m deep piled foundations and then built the pile caps and piers that will support the 66-metre-long bridge deck carrying the road. This weekend, they lifted the last parts of the seven steel beams that will support the bridge deck using a 750-tonne crane.

With the beams now in position, the team will focus on the concrete deck and parapets. Once the bridge has been built, the road will be moved back onto the new bridge and excavation can begin to create space for the railway to pass underneath.

This multi-stage approach was designed to keep traffic flowing and disruption to a minimum.

HS2 Ltd’s Senior Project Manager Elizabeth Longinotti said:

“The A43 is a busy route between Brackley and Northampton and I’d like to thank drivers for their patience over the last three weekends, allowing us to safely lift the enormous steel beams into position while the road was closed.

“With the beams now in place, we can focus on the next part of this complex multi-stage project – pouring the concrete deck ready for the road to be moved onto the new bridge early next year.”

National Highways Route Manager, Bill Freeman, said:

“This is an enormous project which will inevitably impact on people using our roads but we have worked very hard for a long time now to keep that disruption to a minimum.

“For a number of years we have been liaising with HS2 and their partners to develop a plan which would reduce the disturbance to road users during the construction of this huge structure.

“We have also taken advantage of the road closures to expedite our own works improving drainage and repairing the slope along the A43, between Brackley and Syresham, reducing the need for further disruption.”

The 80km stretch of railway that passes Brackley – including the A43 bridge – is being delivered by HS2’s main works contractor EKFB, a team made up of Eiffage, Kier, Ferrovial Construction and BAM Nuttall working with ASC (a joint venture between Arcadis, Setec and COWI).

They worked with National Highways and EKFS’s sub-contractor, Kier Transportation, to construct the temporary realignment, to keep traffic flowing during the work.

EKFB Deputy Project Director Timothée Scherer, said:

“The successful execution of the beam lift represents a crucial milestone in our project. This accomplishment underscores the diligent efforts and unwavering commitment of our team, who have meticulously worked to ensure the safe and efficient installation of the beams. This progress brings us significantly closer to the realisation of this essential infrastructure project, which is destined to substantially enhance regional connectivity and transportation”.

Tim Boardman, Senior Project Manager at Kier Transportation, added:

“It’s fantastic to see the beam lift take effect, and we’re now starting to see the bridge really take shape. Putting this solution into place has required a huge amount of expertise and collaboration with our partners, and we’re proud of the impact it will have. We look forward to moving onto the next stages of the project, while continuing to work hard to minimise disruption for road users and the local community.”

The last few weeks have also seen significant progress for the nearby Turweston viaduct near Brackley, with the 80m long deck beam now slid fully into position. The 591-tonne steel structure was assembled to one side and slid out on special pads covered in PTFE – a Teflon-like material usually found on the surface of a non-stick frying pan – used to minimise friction between the deck and the temporary steel bearings on top of each of the piers.

Turweston is one of five viaducts on the project which use an innovative ‘double composite’ structure, with layers of reinforced concrete on the top and bottom to create a much more structurally efficient box-like span which dramatically cuts the amount of embedded carbon in the design.

In total there are more than 500 bridging structures on the HS2 project – which is designed to improve connections between London, Birmingham and the North while freeing up space for more local trains on the most congested southern end of the existing West Coast Main Line into London Euston.

These range from small footbridges and underpasses, to innovative ‘green bridges’ designed to help wildlife cross the railway, massive motorway bridges and the record-breaking Colne Valley viaduct.

The last few months has also seen significant progress at HS2’s other major viaducts, with the first completed viaduct deck at the complex Delta Junction outside Birmingham and the Small Dean and Wendover Dean deck slides in Buckinghamshire.

Building, Design & Construction Magazine | The Choice of Industry Professionals