The Zakim Bunker Hill Bridge, a cable-stayed span constructed in conjunction with Boston’s 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 France’s wide and deep Tarn Valley. The bridge’s 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.
I grew up not far from the Golden Gate Bridge in San Francisco, with a 4,200-foot suspension span built in 1937. Regular painting is done to prevent corrosion, and those paint jobs are the main form of maintenance, according to this site: http://goldengatebridge.org/research/facts.php
I just visited the arch bridge over the New River Gorge in West Virginia, where We went across the bridge on the catwalk below the deck. That is a very interesting tour. It is difficult to grasp the magnitude of the structure until you see it that close up. All of that steel loaded in compression is an awsome thing indeed.
The bridges with structual elements in tesion are also amazing, but it is clear that they require a great deal more attention and maintenance to remain safe, since tensile failure modes are usually much faster than compressive failure modes, at least that is my understanding. It would be quite educational to have an explanation of how corrosive failure of the suspension elements is prevented.
I think Mydesign has an excellent point: ancient engineers built amazing, beautiful structures, many of which have lasted hundreds or thousands of years, without any of today's sophisticated design tools. In fact, many prehistorians are still arguing about just how some of the oldest ones got designed and built, meaning what tools the engineers actually had in the way of mathematics and physical tools such as a string and chalk for laying out some of the more sophisticated megalithic monuments.
Notarboca, what type of bridges you like most. The ancient type with brilliant art work of structural engineers or the modern bridges made of steel and concrete mix. The ancient bridges are of excellent master piece works of great engineers. They built it in a very nice way, without the help of structural engineering tools and software for stability analyzes.
While I know investing in infrastructure has become some what of a political hot button, there is investment in that area at least where I live, close to the Altantic and where a major river criss-crosses at numerous points. We've had a number of bridges close for long periods of time (the inconvenience is another story) to be renovated and while it's not as exciting and sexy as the Golden Gate or some of the new bridge projects referenced, it is worthwhile engineering. Even some of these smaller projects are pushing innovation. Check out this story Ann did on a bridge made with recycled plastics.
On vacation in Canada last week I came across the construction site for the new Port Mann bridge in the eastern suburbs of Vancouver. It's a cable-stayed bridge that will replace the old steel arch bridge. The contrast between the two bridges is striking...they are both beautiful and utilize the technology, materials, construction techniques, and aesthetic of their respective eras.
I have always appreciated the design and appearance of the ancient Roman bridges and aqueducts. The Sunshine Skyway in Tampa is one of my favorite cable-stayed bridges.
Beth, I think among bridges, construction of hanging bridges are harder and require complex structural designs. The entire structure has to be balanced over the hanging rope and the structural engineers has to possess a good set of design skills for weight balancing.
Henry, most of the ancient bridges, buildings and monuments are look very nicely. We have to really appreciate the designs and the brain behind such projects. Lotus building in Australia, Statue of liberty in US, trade center at burgee Dubai, twin tower at Singapore etc are some of the examples for such brilliant works.
I'm a little spoiled living in San Francisco. I know the Gold Gate Bridge very well. Watching the construction of the new Bay Bridge is exciting. Some of the engineering feats (eg, buildong a new curved ramp leading the the tunnel, cutting out the old part of the bridge and replacing it with the new piece) have been awesome to watch.
One of my favourite bridges is in Washington state over Deception Pass. It's hard to drive across without wanting to stop. Luckily, there are little parking lots on both ends.
An analysis of what’s needed to implement Design for Disassembly and Design for Recycling results in eight strategies engineers can use to design an intentional end-of-life stage into their products.
Government regulations, coupled with growing consumer sensitivity about data and identity theft, require that data storage organizations demonstrate proper protection and due diligence in protecting sensitive information stored inside datacenter enclosures.
When a crane doesn't have a monitoring system, crane owners schedule service every six months and simply scrap the parts they replace, even if a part has had little use and doesn't need replacing. This can cost thousands.
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A quick look into the merger of two powerhouse 3D printing OEMs and the new leader in rapid prototyping solutions, Stratasys. The industrial revolution is now led by 3D printing and engineers are given the opportunity to fully maximize their design capabilities, reduce their time-to-market and functionally test prototypes cheaper, faster and easier. Bruce Bradshaw, Director of Marketing in North America, will explore the large product offering and variety of materials that will help CAD designers articulate their product design with actual, physical prototypes. This broadcast will dive deep into technical information including application specific stories from real world customers and their experiences with 3D printing. 3D Printing is
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