The Mystery of the Iron Bridge

Project Team

Producer

Deborah Perkin - BBC Wales

Historic Adviser

David de Haan - Ironbridge Gorge Museum

Project Engineer

Jamie Hillier - Buro Happold

Erection Team

Royal Engineers, 51 Squadron (Air Assist) Led by Lt. Ben Day

Iron Castings

Nigel Downs - H.Downs & Sons Ltd Huddersfield

Ironwork Technical Drawings

Bill Blake - English Metric Survey Team Heritage

Structural evaluation

Andrew Smith

Site Management

Alex Medhurst - Ironbridge Gorge Museum

Abutments/site support

Staff - Blists Hill Victorian village

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Technical

Ironwork

The original ribs were cast in 2 pieces joining at the centre, each half weighing 5.75 tons. At half scale, they weigh only 15 cwt (680Kg). The span of 1 arc is 50feet (15.24m) and the chord length of each rib was 37 feet (11.3m). In the uprights holes would allow other parts of the bridge to be slotted in place.

Scaffold

The timber poles used for erection are 33 feet (10m) high, though the original scaffold poles would have stood in the river Severn and must have been nearly 70 feet (21.3m). They acted as derricks (cranes) and the frame may have been moved to a new position for each rib.

Ropes

Only hemp ropes were used to build the model,hauled by teams of soldiers. Some ropes have since been replaced by steel cables for safety. A trial lift of a 5 ton weight using the scaffold, hemp ropes and pulleys required 25 people to raise it from the ground.

Abutments

The original abutments are in stone, not brick as shown here, they provide support for the base plates. Only the middle 3 base plates out of a set of 5 have been used, these are only 1" (25mm) thick, unlike the originals which were 4" (100mm).