Jackfield Bridge, Ironbridge Gorge, Shropshire
1994
Jackfield Bridge, located 1 km downstream of the Iron Bridge, is at the centre of the Severn Gorge World Heritage Site. It replaces the reinforced concrete Free Bridge, built by public subscription in 1909, that had suffered from decayed and spalling concrete and had been condemned following routine assessment in 1986.
More than anything, the new bridge was designed in response to a heritage area where the heritage is that of engineering innovation. The aim was to use innovation to match the vigorous, challenging approach of Shropshire's original iron ironmasters.
Shropshire County Council required that the new bridge should have no supports in the river, which is prone to flooding, and that the deck should be maintained well above flood level. It required also that the bridge be on the same level as existing roads.
The design constraints set the engineering challenge of supporting a deck less than 1.0m deep across a 60m span. The constraints and the design challenge were met with an asymmetric cable-stayed structure on the same line as the demolished Free Bridge.
The new bridge is deliberately’ narrow, with tight bends on the approaches to match the winding road system of the Severn Gorge. It is designed for normal traffic loadings but carries a 17 tonne ‘environmental’ weight limit to discourage heavy vehicles being driven through the World Heritage site.
Fact file
Client
Shropshire County Council
Architect
Percy Thomas Partnership
Main Contractor
Alfred McAlpine Construction Limited
Structural Engineer
Gifford & Partners
Steelwork Contractor
Westbury Tubular Structures
