29 October 2009

Sheffield Parkway Bridge revealed

Back in August, I wrote about Yorkshire Forward's decision to drop the RIBA-competition winning footbridge design from Ramboll and Tim Nørlund Jensen on the grounds that its cost had increased beyond the original £1.5m budget, and to replace it with a new design. Mr Jensen was not best pleased, believing he had carried out substantial design development on the original scheme, without ever being paid.

The "iconic" bridge design (shown right), was to span the A630 Sheffield Parkway near Rotherham, providing a new bridleway and footway route.

Now, the replacement design has been submitted for planning consent, and we get the chance to see whether, as one commenter on this blog previously asked, "an over-ambitious competition-winning showpony [has been] replaced with a cut price and cheap substitute." The full planning submission is available online [PDF].

The new bridge (pictured below) has been designed by Scott Wilson, and is a 49m span hybrid Vierendeel truss and bowstring arch structure.
The trusses are 3.5m deep, and made from circular hollow steel sections. It's somewhat similar to a footbridge over the A27 at Tangmere in West Sussex, although not identical: the web members are more highly splayed rather than arranged radially, it lacks the Tangmere bridge's peculiar secondary arch, and the opportunity has been taken at Sheffield to adopt a much more interesting parapet.

So, neither a showpony nor the cheapest substitute, there's a welcome desire to keep it a little more interesting than Yorkshire Forward's budget-consciousness might otherwise have implied.

A number of lessons remain apparent.

RIBA design competitions remain a poor way to get a bridge built, and competitors are accepting an incredibly poor investment-to-reward ratio. Of 393 entries to four open contests (New Islington, Bootle, River Douglas, Sheffield), only 2 made it to planning permission stage (New Islington, Bootle), and only 1 is actually being built (Bootle).

There appears to be little serious scrutiny of the likely costs of designs presented, with Sheffield being one of three recent RIBA contests (the others being River Wear and River Avon) where the winner was found to require far more than the original budget (in two other contests, New Islington and River Douglas, it's unclear if there ever was a real budget).

Promoters simply should not be going down this route if they either lack the money for their bridge, or are unable to sensibly select a design that meets their budget. The cost to the industry is enormous, and it appears that vanity and ambition have often trumped common sense.

See also:
Bridge competition debris part 3: Sheffield Parkway

No comments: