The Iron Bridge - How was it Built?

Page 3 of 6

• 1. A construction mystery
• 2. Building begins
• 3. Arches and ribs
• 4. Deck bearers
• 5. Facts and figures
• 6. Find out more
• Print entire article

Arches and ribs

Stage 3

Using the same scaffold frame but leaning it over slightly less each time, two more arches were completed in the same way. Temporary timber braces made the structure rigid, and these were later replaced by iron castings.

Stage 4

The derrick poles were next lent in the downstream direction allowing the remaining two ribs to be erected, starting with the one furthest away. All five frames were then braced by diagonal and horizontal castings, which straddled the uprights. The arches and the uprights were also tied together near the base plates by short horizontal braces. With all five Lower Rib arches in place, the ironwork was free-standing and strong enough to be used as a scaffold for lifting lighter castings. There were still no abutments at this point.

Stage 5

The rest of the middle frame was built next, starting with the Middle Ribs, followed by the Outer Verticals, then the Outer Ribs, all held the correct distance apart by a series of decorative radial castings. Finally the decorative Circles and Ogees were added at the upper levels. The abutments were built up to their final height behind the Outer Vertical during this process. The scaffold was dismantled and the derricks re-sited so the same sequence could be repeated for the remaining frames.

NextPrevious

Published: 2002-01-01