Tuesday, September 9, 2008

Building Better Bridges

Roads and Bridges magazine devotes itself to issues related to today's wheel based transportation infrastructure consisting, as the journal's name suggests, primarily of roads and bridges. In the August 2008 edition, editor Bill Wilson in his article "Ahead of Its Time" summarizes the successes in building the I-35W St. Anthony Falls Bridge in Minneapolis. This new bridge replaces the prior one that collapsed without warning in August of 2007. The article points out the faster than expected progress that was made, and the challenges faced in trying to quickly replace the faulty structure that had fallen last August.

From his article, it is clear that much intelligence and planning were involved in building the new bridge. This accomplishment reflects the many years of experience by those who designed and built the new structure. In the same publication,
authors John Chiglo and Alan Phipps in their article "Brain waves over water waves" talk about the advanced technologies employed in the bridge that would help alert authorities to any potential problems before any serious failure.

In many ways, the new Minneapolis I-35W St. Anthony Falls Bridge represents the state of the art in infrastructure design and construction. Of course, all of this costs a great deal of money: $234,000,000 was the bid made by the primary contractor and the design team. Given the large number of bridges in the USA, some far longer that the one in Minneapolis, replacing all bridges with this kind of new construction will cost a very large amount of money. When the original Minneapolis bridge collapsed, many were worried that other bridges could suffer a similar fate, since many were reaching the end of their original projected lifespan, and just about all bridges, new or old, support more traffic than they were originally designed to hold.

Cars and trucks give bridges a tremendous pounding, which is why they must be built strong in the first place, and why they wear out over time. Their cement and steel components must be strong because the bridge is doing a yeoman's job in allowing thousands and thousands of heavy vehicles to cross over water. So, these bridges must be costly to build and costly to maintain, and of finite lifespan.

There is way to better use all that money needed to build bridges (and roads and elevated roads, too). A transportation system that does not require massive bridges would be much more efficient and economical. Our Aeroduct System, discussed in these blog entries, and on our website, will require passage over water in guideways that are far lighter, cheaper and longer lasting than any automobile/truck bridge could be. Bridges today are basically beat with a hammer every second of every day as heavy cars and even heavier trucks cross them. In contrast, the vehicles in our Aeroduct System glide through their guideways on a cushion of air, having a very light touch on the guideway surface. Aeroduct bridges can still be built using the intelligence and advanced sensing technologies available for cement and steel bridges, but with lighter and more flexible materials and much longer lifespans.

The color sketch below shows the simplicity of an Aeroduct bridge crossing a river. For wider rivers or other bodies of water, supports would be needed for the guideway, but those supports will have much less work to do than the supports for the bridges of today. The replacement of the much of our aging bridge infrastructure with the Aeroduct infrastructure would save a great amount of money in the building and maintenance of the structures, and the safety of using them. This is just one way of many Aeroduct System installations can make transportation far better than it is today.

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