The taper suspension bridge (also known as the taper principle) is a bridge design patented by James Dredge in 1836.[1]
On a conventional suspension bridge, the whole deck is suspended by vertical cables, rods or chains from a single cable or chain slung between two supporting towers. The taper suspension bridge, devised by James Dredge in the early nineteenth century, differs from the conventional suspension bridge design in that it effectively functions as a double cantilever bridge. Each opposing cantilever system is self-supporting. The cantilever half-deck structure of each cantilever is suspended from angled chains, which hang from a tapered main attached to the top of the tower and to the outer end of the half-deck. The main chain taper is achieved by incrementally reducing the number of links stacked across the chain's width as it moves farther from the support tower.
The advantage of this taper system is that it results in a more cost-effective design compared to conventional suspension bridge of the time because it uses less iron and is quicker to build.
Of the 36 known examples of bridges started or completed by Dredge using this design, 7 are known to have survived.
| Name | Date built | Original location | Current location | Span | Image | |
|---|---|---|---|---|---|---|
| 1836 | Bath, England | As built | 150feet | |||
| 1844 | River Blackwater, Caledon, Northern Ireland | Relocated to Caledon[2] | ||||
| 1845 | River Blackwater, Caledon, Northern Ireland | As built | ||||
| 1845 | Pewsey, Wiltshire, England | As built | ||||
| 1847 | Castledawson, Northern Ireland | As built | ||||
| 1854 | River Oich, Aberchalder, Scotland | As built | 155inchesft6inchesin (ftin)[3] | |||
| General's Well Bridge[4] | 1853[5] | River Ness, Ness Islands. Inverness | Relocated to Ness Islands Railway, Whin Park, Inverness | 97feet |