The conventional option, which comes within a budget already promised to Sunderland by central government, is a five-span girder bridge:
Not even slightly exciting, and relatively risk free, depending on how much work has been done on geotechnical, hydraulic and ecological studies in the river, where there will be a number of foundations. Sunderland describe it as "tried and tested" which is clearly a dig at the alternative, untried, and untested iconic design by Spence and Techniker.
The iconic option is much as seen before, although the higher-resolution image (click on the picture below) seems to show the cable arrangement more clearly.
Sunderland allude to the likes of Jimmy Choo and Gucci by describing it as a "designer bridge" and pointedly note that the £30m extra it would cost could pay instead for 6 new schools. That £30m extra is interesting, because it implies they have a cost estimate significantly higher than the bridge's designers have suggested.
They also (wisely) draw attention to the issue of risk, stating that "the risk of construction and future maintenance costs rising is higher for a project that has unique features than for a tried and tested one". This is difficult stuff, because there will be very few members of the public who have any way of judging the real risks of an unbalanced cable-stay bridge like this. These might include dynamic behaviour problems, construction difficulties, huge foundation requirements, impact on birds, all sorts of things.
Before the decision was taken in July 2005 by Sunderland to make this option their competition winner, they recognised that it was "of a striking and unusual form ... believed to be unique". They commissioned an independent review, which concluded that "construction of the bridge is challenging but achievable" and its "dynamic performance ... is extremely complex", with designer Techniker confirming that detailed analysis and testing would be needed to review this issue. The review also concluded that the bridge concept may require amendment both to meet the budget and the possible dynamics issues. All this can be found online at Sunderland's cabinet minutes for 27 July 2005. It's not apparent to what extent the design has been further developed since then to address these points.
The Sunderland Echo is running a poll for the two designs, currently running at 92% in favour of the iconic bridge, and 8% for the low-cost option. This suggests residents are happy to pay the £263 council tax surcharge that their council says would be required. However, the Echo quotes several people disputing the cost, which they believe would be much lower. At the risk of provoking a deluge of comment from bridge-happy Wearsiders, I think the bridge's proponents generally lack the expertise to pronounce on this quite as confidently as they are doing. The bridge design competition world is littered with examples of unusual bridge designs where the real risks were never appreciated at the outset, and which ended in failure.
What still puzzles me is quite why Sunderland have chosen to pursue this public consultation. Public support for anything that allows Mackems to boast at being better than their Geordie neighbours is no surprise. But they have no sensible way of judging competing claims regarding feasibility, cost and risk, other than a natural inclination to trust the underdog (Spence) against the political establishment.