Are stone arch bridges outdated? Perhaps not.
In the final tally of concrete bridges, they tend to last 50–75 years. On the other hand, there are numerous examples of Medieval stone arch bridges still carrying roads, and even tractor-trailer traffic in some cases. The enduring power of well-built stone arch bridges is unquestionable.
Stone Arch Bridges in Modern Times
In recent years various regions in Africa have begun to build stone arch bridges as a means of achieving permanent roads. In Europe, there is talk about building stone arch bridges once more as they simply last longer than concrete bridges. The primary drawback to stone arch bridges collectively is the initial cost. The initial cost of a well-built stone arch bridge is high, due to the large amount of manual labor involved. In places where the price of labor is low, stone arch bridges tend to be favored. Otherwise, concrete reigns supreme as the cost of material is relatively low compared to that of labor.
In the long term a quality stone arch bridge tends to be less expensive than a concrete bridge simply because it lasts longer. The main trouble with historic stone arch bridges is the quality. Many stone arch bridges were built with the importance of deep foundations grossly underestimated. Many early examples also were designed for earlier traffic, with the result that they were narrow. Also, some of the “affordable” stone arch bridges suffer from life-shortening issues, such as using mortar (which leaches out over time) to create the arch angles. And some stone itself simply doesn’t last, such as some grades of limestone in contact with water. But where good foundations were built and the stones were quality and well cut (such as in the bridges built by the ancient Romans) the bridge can last for over a millennium. The end result is that stone arch bridges, when built in a quality fashion, will tend to pay themselves off in the long term. In the short term, stone arch bridges are more expensive, but are built with an eye for the future.
In the final tally, stone arch bridges will never be outdated as long as so many examples from previous centuries are being used. It is possible that they will make a comeback and begin to be built again, if it indeed makes sense to do so. And, all things considered, stone arch bridges have a well-deserved reputation for blending into the landscape in a scenic fashion. Best of all, stone arch bridges, well built, can last for centuries.