The Past and Future of Suspension Bridges

For many centuries, mankind has worked tirelessly to adapt his environment to his needs. This means artificially fertilizing soil, genetically engineering plants, even attempting to create rain artificially (Mone). However, sometimes, water has gotten in the way, so, when man wants to build his roads across them, his solution was: Pick up the road and carry it across.

Many suspension bridges are already well known for their frequent usage. For example, the Golden Gate Bridge in San Francisco, the Union Bridge connecting England to Scotland, and the Brooklyn Bridge, which expands New York City to surrounding islands. Now, according to The American Heritage Dictionary of the English Language, Fourth Edition, a suspension bridge is “a bridge having the roadway suspended from cables that are anchored at either end and usually supported at intervals by towers.” This, though, is simply the skeleton of the concept. There is huge potential in suspension bridges for the future, but, as it is said, we must learn from the mistakes of the past or we will be doomed to repeat them. What makes a suspension bridge work, what hazards lie on the path, and what can we reach with the resources we have today?

The suspension bridge is fundamentally supported by stringing up the road on heavy-duty steel cables, usually wound in large groups. A long, parabolic wire runs the length of the bridge on both sides. This cable is held taut, suspended on the towers and connected to the anchorages on either side, which anchor the wire and channel stress into the Earth. (Morrissey, Michael) The cables running from the side of the road to the parabolic cable transfer all of the weight to the longer cable, but these cables are more slacked than one would think. Th...

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..., which, when put under stress in temperatures below that which was intended, instantly became a break in the bar, throwing all of the weight onto the southern chain, which buckled under the sudden pressure. Post-investigations yielded results showing a poorly maintained bridge, with many cracks and corroded areas, the bridge was bound to have collapsed soon, and regular maintenance could have prevented the disaster.

In the future, buildings will get taller, so this simple concept of stress distribution shown in bridges could build walkways between high floors of tall, adjacent buildings. The buildings themselves would function as both towers and anchorages, supporting via wires walkways, which would have scenic views and great accessibility. Also, suspension bridges, unlike arch and truss, are not limited by distance. As required, they will get longer in the future.