1966 First Severn Bridge in England

(Historic Bridges; Satellite; Satellite, 571 photos; Viewpoint Satellite, 1,390 photos)

This is not the first bridge across the Severn River. The Iron Bridge would have to be earlier. It would be the first bridge near the mouth of the river.

Street View, Mar 2011

10th of 22 construction photos in WalesOnline
A [130-ton, 40m long] section of the road deck is lifted into place.
"From 1966 to 1996, the bridge carried the M4, before the Second Severn Crossing opened."

 

Bill Brown's Bridges
"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 He is credited with designing the innovative aerodynamic box girder deck, which superseded the complex trusses used on earlier major suspension bridges in the UK (Forth Road Bridge) and the USA.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."
987.5m main span
1,839m total length

 

Bill Brown's Bridges
I remembered correctly, this bridge used wind-tunnel testing to develop the new box-girder deck shape. But I didn't know that Bill got wind tunnel time because the truss deck that was being tested got destroyed. 

 

NationalHighways
Blecause it does not have wind barriers, this bridge is closed to traffic if gusts above 40 knots (46mph) are expected. When closed, traffic is diverted to the second bridge. The second bridge, which has wind barriers, can handle traffic up to 70 knots (80mph).
Tolls were removed for both bridges in 2018.

Bridges Now and Then posted
On the UK's first Severn Bridge, c. 1963. (Media Storehouse)
Dave Frieder: Footbridge for Main Cable Construction.

"Unlike most suspension bridges the cables carrying the deck are not vertical but arranged in a zig-zag style. Engineers used this arrangement of cables to reduce vibration. 'Stockbridge dampers' were also used to reduce vibration. The dumb bell-shaped devices suppress vibration caused by wind on overhead power lines by dissipating energy. Engineers decided on the shape of the bridge after extensive wind tunnel testing. Much of the structure was built in Chepstow with sections floated down the river to the construction site and then hoisted into place." [ice]

HistoryPoints, Photo by Hugh Pritchard
"Two concrete piers, 988 metres apart, were built up from the bed of the estuary. The Aust pier rests on a limestone outcrop while the Beachley pier rests on hard mudstone. The bridge’s towers were made of high-tensile steel, weighing 2,700 tons in total."

bbc
The Severn Bridge in the 1970s
This bridge was built at the location of the ferry service that it replaced.