Ancient Romans seemed to have things all figured out. Sure, the Etruscans and ancient Greeks knew about true arches, but they took it a step further: they were the first to understand the value of arches for bridge construction. And while that may be more than a thousand years back, some of the bridges still exist today.
Colin O’Connor, an engineer, compiled a list of Roman bridges which included more than 300 Roman stone bridges for traffic, 34 Roman timber bridges and 54 Roman aqueduct bridges. A large number of these structures are still standing today and are used to carry vehicles.
Of course, years later, the Roman design was improved upon and even built with different materials. All that said, any design is subject to certain flaws and a couple of advantages.
List of Pros of Arch Bridges
1. They are resistant.
Other bridge designs displace force or exertion from vehicles towards the middle which leads the bridge to be weakened. However, arched bridges do not possess this problem at all because the force is equal as the bridge is weighted on both ends. Plus, the arch is located in the middle which means the force isn’t that pressing on the middle portion. As such, they are more dependable and durable for use in highways and tunnel overpasses.
2. They can be made from different materials.
Simple materials can be used in building arch bridges. Stone and brick, for example, are strong in compression but can’t resist much force in tension. As such, masonry arch bridges are designed to always be under compression.
Today, a lot of modern arch bridges are made from reinforced concrete. In addition, other materials such as cast iron and steel have also been used.
3. They turn stronger as time passes.
Arch bridges are built to be under compression and they become stronger with each passing transport. As such, they strengthen through time rather than weaken.
List of Cons of Arched Bridges
1. They are limited in size.
A better term for this is costly. Building an arch bridge requires a certain start and end point. Several arches need to be built in order to accommodate the projected weight it’s intended to carry. In case extra arches can’t be built, more money needs to be spent on extra loads so it can lift all the mass it’s expected to.
2. They take time to build.
While bridges take months and even years to complete, arch bridges may take longer. They have to be built precisely and in a certain way. The process is further lengthened should the materials chosen be hard to find.
3. They need more maintenance.
Most of the time, natural materials are used in the construction of arch bridges which brings the design at a disadvantage. Harsh winds will see the bridge flex and move causing the mortar which combined the natural elements to crack and disintegrate as time passes. To avoid such a scenario, regular maintenance is required to extend the life of the bridge.