
Wendover Dean Viaduct
Located south of the town of Wendover in Buckinghamshire, the 450 metre-long viaduct will be the first major railway bridge in the UK to be built with a ‘double composite’ structure, using significantly less carbon-intensive concrete and steel in comparison to a more traditional design.
Once construction is complete, the historic field boundaries and hedgerows will be recreated to provide uninterrupted access for farmers and local residents. A mix of trees and shrubs commonly found across the Chiltern chalk hills will be used for new woodland planting around the viaduct, including Oak, Beech, Hazel and Wild Cherry.
Viaduct construction
The viaduct deck was assembled and slid into place in three stages, with the final stage being completed in August 2024.
The enormous piers – some up to 14 metres high – that support the deck are made up of a series of hollow pre-cast concrete shells that are placed on top of each other and filled with concrete and steel reinforcing. This approach was chosen to enable a crisp, clean external finish to the concrete, cut the amount of work on site, and reduce disruption for local residents.
The 38 steel beams that go on top of the piers for the viaduct deck to rest on were delivered at night to reduce disruption for the local community. Twenty five metres long, the beams were transported on the back of extra-long lorries, with traffic management in place to stop traffic as they negotiated corners and narrow sections of road. Instead of using solid pre-stressed concrete beams to form the spans, the viaduct will use two steel beams sandwiched between two layers of reinforced concrete to create an innovative ‘double composite’ approach that is lightweight and super strong.

Slide 1 of 6: Aerial image of completion of 8 month Wendover Dean Viaduct deck slide August 2024

Slide 2 of 6: Aerial image of completion of 8 month Wendover Dean Viaduct deck slide August 2024

Slide 3 of 6: Aerial view of Wendover Dean Viaduct deck push looking south May 2024

Slide 4 of 6: Aerial view of Wendover Dean Viaduct deck push May 2024

Slide 5 of 6: The beams that will form the deck of the Wendover Dean Viaduct January 2024

Slide 6 of 6: EKFB staff pass the first Wendover Dean steel beam on site June 2023.
Viaduct design
The slender design of the viaduct created using the ‘double composite’ approach with the beams not only cuts the amount of carbon-intensive concrete and steel needed it also reduces the silhouette of the structure viewed from across the valley. Nine evenly spaced piers will support the deck of the viaduct and will be placed to carefully reflect the near symmetry of the ground beneath.
The beams themselves will be made from weathering steel, which will age to a characteristically dark russet finish and echo the natural tonnes of the surrounding landscape. Total steel weight is around 1,400 tonnes and will be topped with a concrete deck, which will carry the track and built-in noise barriers.
When viewed from a distance, against the weathered steel, the pale concrete parapet will appear as a thin horizontal band hovering over the slender piers as it glides over the valley and make the whole structure look thinner. This effect will be further emphasised by the viaduct piers, which have been extended to almost connect with the parapet, helping to give the appearance of a light and narrow structure.

Slide 1 of 11: Artist's impression of a masked view of the Wendover Dean Viaduct.

Slide 2 of 11: Artist's impression of the view of the Wendover Dean Viaduct portal (1).

Slide 3 of 11: Artist's impression of a distant view of the Wendover Dean Viaduct (1).

Slide 4 of 11: Artist's impression of the view of the Wendover Dean Viaduct portal (2).

Slide 5 of 11: Artist's impression of a distant view of the Wendover Dean Viaduct (2).

Slide 6 of 11: Artist's impression of a distant view of the Wendover Dean Viaduct (3).

Slide 7 of 11: Artist's impression of a close up view of the Wendover Dean Viaduct.

Slide 8 of 11: Artist's impression of the view of the Wendover Dean Viaduct.

Slide 9 of 11: Artist's impression of the view of the Wendover Dean Viaduct portal (3).

Slide 10 of 11: Artist's impression of the view of the Wendover Dean Viaduct portal (4).

Slide 11 of 11: Design diagram of a cutaway image showing the double composite structure of the Wendover Dean Viaduct.
Key facts
- Length: 450m
- Height: 14m
- Number of piers: 9
- Construction approach: ‘Double composite’ steel beams for strong but lightweight spans.
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