The Zakim Bunker Hill Bridge, a cable-stayed span constructed in conjunction with Bostonís Big Dig highway relocation project, is an excellent example of how a distinctive design can become a symbol of a city. It is now virtually mandatory for people engaged in television interviews originating from Boston to be shown with that bridge as backdrop.
Among the most dramatic of newer cable-stayed bridges is the Millau Viaduct, which carries vehicle traffic high over Franceís wide and deep Tarn Valley. The bridgeís roadway is so high off the ground that it appears on occasion to float above the clouds that form beneath it, but the bridge earns equal distinction for the gently arcing curve of its deck and its overall striking appearance. I have lost count of how many correspondents have sent me still and moving images they took while driving over this bridge, but I never tire of admiring their pictures.
Not all striking bridge designs are towering, long-span highway bridges. Many pedestrian bridges of exceptional aesthetic value have been designed and built in recent years. Among the most widely known is the London Millennium Bridge, the design of which was the collaborative effort of the Arup engineering firm, Foster and Partners architects, and the sculptor Anthony Caro. It resulted in a striking low-slung suspension bridge, which to many people is hardly recognizable as one. Unfortunately, the bridge became somewhat of an embarrassment when its walkway swayed so much that it had to be closed within three days of its opening. The problem was fixed by retrofitting the bridge with stiffening struts and dampers, and it has become one of the most popular new tourist attractions on the River Thames.
Among the most highly anticipated of new bridges is the replacement for the east span of the San Francisco -- Oakland Bay Bridge, which was damaged in the 1989 Loma Prieta earthquake. Rather than spend $1 billion to retrofit the old structure, the California Department of Transportation argued, the money could be better spent on a new and distinctive span. The centerpiece of the new bridge, whose final cost will likely exceed $6 billion, is an unusual structure -- a self-anchored suspension bridge, one over whose single tower cables are draped and then connected to the ends of the roadway. Expected to be completed next year, the structure is sure to bring bridge enthusiasts and their cameras to San Francisco Bay.
I expect I may be the recipient of some photos of the new Bay Bridge, and I will welcome them. Different people have different opportunities to see different structures from different perspectives under different environmental conditions. Unlike the fine art masterpieces hanging in a museum under controlled temperature, humidity, and lighting, bridges must be works for all seasons. And the best of them truly are.