Small Dean Viaduct

Buckinghamshire, England

2019 — ongoing

Client HS2 Ltd

Road & Rail

Small Dean Viaduct carries HS2 trains diagonally across the A413 and local rail lines at the northern edge of the Chilterns Area of Outstanding Natural Beauty.

‘The HS2 Independent Design panel applauds the quality of the project team’s collaboration with Buckinghamshire Council. The design of Small Dean Viaduct is successful: it is an elegant structure, enhanced by well crafted details.’

HS2 Independent Design Panel Report

A close-up view of a modern architectural structure with angular, ribbed elements casting shadows. The light hitting the surface creates a warm, golden tone. A concrete pillar is visible at the bottom, with trees in the background.

Set low in the landscape, the distinct viaduct features a ‘double composite’ structure; an engineering innovation that optimises the structural performance of concrete and steel to create strong and efficient spans. The deck is supported by five carefully positioned and elegantly sculpted Y-shaped piers, visibly clasping the beams above.

A serene suburban scene at sunset, featuring an empty road with marked lanes leading towards a modern overpass. The grassy roadside is dotted with wildflowers, and trees gently sway, casting soft shadows on the pavement.

A high-speed train travels across a modern bridge surrounded by green trees at sunset. The landscape features rolling hills and fields in the background, creating a serene and picturesque scene.

A scenic road with a 40 mph speed limit sign painted on the surface. The road curves under a bridge, flanked by trees and grass, with a few cars driving in the distance. The sunlight creates a warm, peaceful atmosphere.

A concrete bridge support beneath a road, surrounded by a field of purple wildflowers. Sunlight casts shadows, suggesting early morning or late afternoon. Trees with green foliage are visible in the background.

A serene landscape view shows sunlight cast on a bridge pillar at dusk. The foreground features a field of wildflowers and shrubs, with trees and a distant horizon in the background, all bathed in warm, soft light.

A modern bridge stretches over a road bordered by fields of purple and yellow wildflowers. A car drives on the road, while a person walks nearby. The scene is bathed in warm, golden light, suggesting early morning or late afternoon.

Prominent steel plates extending from the central girders stiffen the structure, while creating a dynamic interplay of shadow and light. The low maintenance weathering steel will take on dark russet tones over time, harmonising with surrounding foliage and increasing the prominence of the pale concrete piers and parapet edges.

Small Dean is one of a series of viaducts by Moxon for HS2, including its sibling structure Wendover Dean Viaduct, also a collaboration between Moxon, EKFB, and ASC.