Tuesday, 16 September 2014

Jackfield Bridge

I had something in mind for this week's ABC and remember thinking it would be perfect but alas whatever J it was has slipped as easily out of my mind as it did in.  Happily this soaring structure also begins with a J 
It is the Jackfield Bridge over the River Severn, just a few miles away from the iconic Ironbridge I showed last week. It replaces an earlier bridge which was the first toll free bridge crossing of the gorge and was funded by public subscription with the land donated by the land owner. Built by Liverpool Hennebique to an open spanned arch design by LG Moushell it was an early example of the use of reinforced concrete.
Here is the grand opening of the what was then called the Free Bridge or Haynes Memorial Bridge in 1909.  A 14 ton steam roller was sent over to load test the bridge.
The years were not kind to the Free Bridge with decaying concrete carbonising. chloride attack from de-icing salts and rusting steel.  Repeated repairs were tried but the tonnage limit kept having to be reduced until by 1986 there was a 3 ton limit.  It was decided to demolish and replace the bridge which created its own design contraints due to the unstable banks caused by the river undercutting and the repeating River Severn floods, one of which can be seen in the above photograph taken in 1950s of a bus crossing the Free Bridge.

The design also had to be sympathetic to the Ironbridge Gorge which is designated a UNESCO Heritage Site and the ultimate result was a counterpoint to the old ironmasters bridges that cross the river.
The new Jackfield Bridge has an overall span of 57m with a 30 ft steel tower and cable supports and was opened in 1994 (designed by Gifford and Partners, built by McAlpine Construction).  As part of the opening celebrations a vintage steam roller trundled over the bridge (to recreate the original 1909 load test) accompanied by its modern counterpart.

What I also found fascinating about the bridge was not only had they to stabilise the ground before building could begin but because of the narrow winding roads to the gorge everything had to be brought to the site in sections (unlike those early bridges when the industrial revolution was in full swing and all the foundries were still operating nearby).  The tower was delivered in 4 sections and hoisted into position by a 200 tonne crane.  The crane itself was so large it also couldn't navigate the roads and was delivered in sections taking 2 days to erect on site.
Photograph from the Tata Steel site.

An entry to ABC Wednesday, a journey through the alphabet, this week sojourning at J here


Roger Owen Green said...

nice post. But I HATE when I forget!

mrsnesbitt said...

Oh yes I know that ABC Wednesday feeling well! Oooooooooooooh I think at the time - how perfect...then all is forgotten in the wink of an eye!
Denise ABC Team

Gerald (SK14) said...

Fascinating account - especially the steam rollers and having to build the crane on site because of narrow roads.

fredamans said...

Interesting bridge, what a history!