31 October 2014

French Bridges: 3. Rognonas Suspension Bridge, Avignon

After the second world war, several European countries commenced a programme of reconstruction and development. In France, this led to a series of modern suspension bridges, of which the first was the Rognonas Bridge at Avignon.

This bridge spans 255m across the Durance River to the south of Avignon. Completed in 1950, it is very similar to the 238m Ancenis Bridge built three years later. Both bridges have truss-stiffened decks, with the riveted steel truss partly above and partly below roadway level, and both have concrete portal towers with concrete latticework at their top.

Structurae credits the construction of both bridges to Baudin-Châteauneuf, and lists Jean Courbon as designer of the Ancenis span. Boussiron is credited with involvement in building the Rognonas bridge.

Richard Scott comments on the design:
"Its heavy half-through truss contrasted with a finely etched diagonal grillage in the top portal strut of its concrete towers that, for all its elegance, was taxing to build".
Looking back through my photos, there are a few aspects of the bridge which seem particularly notable.

It's not just the concrete lattice between the towers that is visually attractive - the towers are generally well finished, with some pleasing contrast between rough and smooth surfaces. They are also nicely proportioned, widening only fractionally at the top to accommodate the main cable saddles.

The bridge trusses are discontinuous at the towers. That's not a common arrangement in 20th century suspension bridges, and I wonder how many examples there are.

The main cable arrangements are unusual only if compared to larger spans, being assembled from several smaller cables clamped together, rather than having been aerially spun.

This is a fine bridge where simple, straightforward engineering has been married to a minimalist and highly attractive aesthetic.

Further information:


Imre said...

Another example for clamped main cables is the Elisabeth bridge in Budapest ( http://www.bridgesofbudapest.com/bridge/elizabeth_bridge ) Compared to the Rognonas Bridge, the connections of hangers to the main cables is even more odd: at Rognonas, a fork is transmitting the hanger force, while at the Elisabeth bridge, the two-shank hanger is slung around the clamp. (http://hu.wikipedia.org/wiki/Erzs%C3%A9bet_h%C3%ADd#mediaviewer/File:Budapest_Elisabeth_bridge2_B%C3%85n.JPG)

Bridge Ink said...

I saw this beauty 20 years ago, The:

"---finely etched diagonal grillage in the top portal strut of its concrete towers that, for all its elegance..."

was certainly was worth the effort!

David Denenberg said...

On the topic of long-span "clamped" twisted strand cables, see Deer Isle Suspension Bridge: https://www.flickr.com/photos/suspensionstayed/sets/72157622506886080