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When it comes to bridge design, what is the balance between structural integrity, architectural beauty and usability?

I was contacted by an Arch blog and asked to respond to a question of the day sort of thing. Little did I know they only wanted 300 words. Would have been nice to know ahead of time. So here is my long winded answer…

What is the balance between structural integrity, architectural beauty and usability in bridge design? Well, a typical engineering answer would be structural safety first, usability second, cost third and the architectural look of a bridge a distant fourth. Architectural beauty may not even rank that high among some bridge designers.

Before I go too much further I have to point out the obvious, bridges are unique structures in the design world. Structural load carrying members are typically exposed without the protective cover that buildings enjoy and have to perform flawlessly for decades. They are often located in harsh salt laden environments, designed to be built by a variety of contractors and on top of that, they have to be prepared for unknown future loads. No wonder bridge designers are a little touchy when it comes to questions about the look of a bridge.

Take for example, the most famous bridge in the world, the Golden Gate Bridge, as of May 30, 2012, it had 1,970,331,117 vehicles cross the bridge. Imagine designing a bridge that opened in 1937 to carry two billion vehicles and last over 75 years! Now imagine you are responsible for the structural design and the safety of the public using the bridge.

Three factors play a large part in the way an engineer approaches a bridge design. First, engineers are taught in college to build the safest structure at the most economical price. We take classes in engineering economics and learn the tao of the benefit cost ratio. This makes complete sense when you think about how most bridges are financed, through public monies. Woe to the public agency that misuses government funds to construct a bridge.
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Garden bridge – Bridge Concept

HP has a new post on a proposed garden style bridge.

As HP pointed out, the bridge design is not really responding to the site. Meaning the bridge was designed without the context of the area in mind and you could plop it down anywhere. I always thought context was the mantra of good design?

It is an attractive bridge but is it worth being the most expensive pedestrian bridge ever built. Now that I have joined the party of Yes, of course they should do it! Build two!

Here is my version from two years ago.

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