Severn Bridge 1966

Severn Bridge 1966

© Craig Joiner

The Bridge

Dr William (Bill) Brown was the principal designer working with Sir Gilbert Roberts and the Freeman Fox & Partners team on the Severn Bridge. He is credited with designing the innovative aerodynamic box girder deck, which superseded the complex trusses used on earlier major suspension bridges in the UK (Forth Road Bridge) and the USA.

Bridges all over the world are descended from the design and engineering of the Severn Bridge.

Bill Brown's Aerofoil Hollow-box Deck

Cross-section of the Severn Bridge deck.

Severn Bridge

Linking England and Wales

Key Facts

Four-lane motorway bridge

First major bridge with a box-girder deck

A new chapter in bridge design



Across the River Severn

Between Aust (England) and Beachley (Wales)

Designers / Engineers

Dr William (Bill) Brown

Sir Gilbert Roberts

Freeman Fox & Partners

Mott, Hay and Anderson


Suspension bridge with diagonal hangers

987.5m main span

1,839m total length

Main contractors

Cleveland Bridge & Engineering Co. Ltd.

Dorman, Long and Co. Ltd.

John Howard and Co. Ltd.


Began 1961

Opened 8 September 1966

The Bridge Construction

There was pressure to minimise cost and use less steel on the Severn Bridge. Bill’s studies showed that a shallow welded box construction would have good torsional stiffness and be lighter and easier to build. An earlier truss deck design was accidentally destroyed during wind-tunnel testing and Brown and Roberts had the opportunity to test the new deck. It was found to have good aerodynamic performance that deflected the force of the winds.

The roadway deck was constructed from 88 box sections, each 40 metres long. They were assembled on the riverbanks of the adjoining River Wye, floated into position and hoisted to road level. The Severn Bridge replaced the Aust ferry, which had carried up to 19 cars at a time over the river. The long queues for the ferry that used to stretch two or three miles were now a thing of the past.

In 1966, it became an essential part of the new M4 motorway, reduced travelling time between London-Bristol-Cardiff and helped the economic development of South Wales. The Severn Bridge proved very popular, and soon up to 20,000 vehicles a day were crossing it. A new second Severn Crossing was constructed in the 1990s.

"It is a great artefact, a magnificent outline against the sky, which is a thing of sweeping grace, of light and seemingly effortless power."

William Dreghorn, author, Geology and the Severn Bridge

"Awesome in its striking simplicity. It is a monument to contemporary design and technique."

Bill Brown was part of the Freeman Fox team that received the Royal Academy of Engineering MacRobert Award gold medal (left) and citation for the Severn Bridge.

Explore a 3D model of the Severn Bridge

A model created by Wurzeller is featured on the 3D Warehouse website and can be viewed in 360 degrees from the link below.

View 3D Model

Other long-span bridges