Bucks Council approves construction of key HS2 viaduct in Wendover

HS2 has received planning approval for its major Small Dean Viaduct in Wendover, the rail group announced this morning (19 April).

Bucks Council has approved construction of a 345m long viaduct that will carry trains across the A413.

Designed to be seen from close-up, the viaduct is one of only two places in the Chilterns where the HS2 route will be above ground level, with the underside of the viaduct just 6m above the road, supported by five ‘Y’ shaped piers.

A ‘double composite’ structure will be used just like at the nearby Wendover Dean Viaduct. This involves two steel girders sandwiched between two layers of reinforced concrete to create a strong but lightweight span.

Both viaducts were designed by HS2 Ltd’s main works contractor, EKFB - a team made up of Eiffage, Kier, Ferrovial Construction and BAM Nuttall - working with their design partner, ASC (a joint venture between Arcadis Setec and COWI) and specialist architects Moxon.

HS2 design director, Kay Hughes, said: “By providing a cleaner, greener way to travel, HS2 will help cut the number of cars and lorries on our roads, cut demand for domestic flights, and help the fight against climate change.

“But it’s also vital that we cut carbon during construction, and the innovative approach to Wendover’s Small Dean Viaduct is a great example of how HS2 can deliver elegant viaducts at a fraction of the normal carbon footprint and save construction time. I’d like to congratulate the design team and look forward to seeing this outstanding viaduct start to take shape over the coming years.”

Trains will pass through Wendover via a tunnel designed to limit disruption.

EKFB’s interface and stakeholder director, Simon Matthews, said: “Small Dean Viaduct is the most high profile of the 15 viaducts that we are delivering across our 80 km central section of high speed 2, and we have been developing our design to respond to the unique challenges of building a sustainable structure that responds to the local environment. Using the guidance in the Chilterns AONB Detailed Design Principles, and working collaboratively with local stakeholders, we are very pleased to receive planning approval for this iconic structure and the surrounding features.

“Works are already underway to prepare for the new viaduct, and over the next two years the foundations and piers will be built alongside the busy A413, before the 5,800 tonne deck will be launched in 2025.”

As well as the main road, the viaduct will also span the neighbouring Chiltern line to London Marylebone and the project will also include the realignment of Small Dean Lane.

The A413 will be realigned to pass under the viaduct, with landscaping in the form of a series of subtle terraces to manage the change in height and interplay between road, paths, railway and viaduct.

Moxon’s managing director, Ben Addy, said: “We’re delighted with the news that Small Dean Viaduct has achieved planning consent, a decision that comes after a productive, design-driven dialogue between the team and Buckinghamshire Council officers on the final proposals.

“The character of the site, combined with the pronounced diagonal alignment and low deck level, will result in an especially dynamic appearance when viewed from the carriageway.”