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How much cost differential is there between a pier and beam bridge and a cable-stayed bridge per square yard of road surface?

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How much cost differential is there between a pier and beam bridge and a cable-stayed bridge per square yard of road surface?

Pier 3 Crossbeam reinforcing bar | This shot is from the eas… | Flickr

a pier and beam bridge

Greenville Bridge | The cable-stayed bridge on US 82/278 bet… | Flickr

a cable-stayed bridge

 

Bridges are essential structures that connect different parts of the land and allow people and vehicles to cross over water, valleys, or other obstacles. There are many types of bridges, each with its own advantages and disadvantages. Two common types of bridges are pier and beam bridges and cable-stayed bridges. In this article, we will compare these two types of bridges in terms of their design, construction, and cost.

Pier and beam bridges are one of the oldest types of bridges. They consist of a series of piers (vertical columns) that support horizontal beams, which in turn support the bridge deck (the road surface). The piers are usually made of stone or concrete, while the beams can be made of wood, steel, or concrete. Pier and beam bridges are suitable for short to medium spans, as they can distribute the weight of the bridge evenly over the piers. However, they also require a lot of material and labor to build, as each pier and beam has to be carefully placed and aligned.

Cable-stayed bridges are a relatively modern type of bridges. They consist of one or more towers (or pylons) that support the bridge deck with cables. The cables run directly from the tower to the deck, forming a fan-like or parallel pattern. Cable-stayed bridges are suitable for medium to long spans, as they can reduce the bending forces on the bridge deck by transferring them to the towers. They also require less material and labor to build, as they use fewer piers and beams than pier and beam bridges.

The cost of building a bridge depends on many factors, such as the size, location, design, materials, labor, and environmental conditions. Therefore, it is difficult to give a precise answer to how much cost differential there is between a pier and beam bridge and a cable-stayed bridge per square yard of road surface. However, based on some examples and estimates from various sources, we can get a rough idea of the cost range for each type of bridge.

According to The Pricer1, the average cost of a pier and beam foundation (which is similar to a pier and beam bridge) is about $10-$15 per square foot. This means that for a 1,000-square foot bridge deck, the cost would be about $10,000-$15,000. Assuming that the bridge deck is 30 feet wide (which is typical for a two-lane road), this translates to about $333-$500 per square yard.

According to Scientific American2, the cost of the New NY Bridge (which is a cable-stayed bridge) is approximately $3.9 billion. The bridge has eight traffic lanes and is the widest cable-stay in the world. The total length of the bridge is about 16,000 feet, which means that the average cost per foot is about $244,000. Assuming that the bridge deck is 180 feet wide (which is roughly 30 feet per lane), this translates to about $1,356 per square yard.

According to Wikipedia3, the cost of the Queensferry Crossing (which is another cable-stayed bridge) is about £1.35 billion. The bridge has three traffic lanes in each direction and is one of the longest cable-stayed bridges in the world. The total length of the bridge is about 8,300 feet, which means that the average cost per foot is about £163,000. Assuming that the bridge deck is 120 feet wide (which is roughly 20 feet per lane), this translates to about £1,358 per square yard.

Based on these examples, we can see that cable-stayed bridges tend to be more expensive than pier and beam bridges per square yard of road surface. However, this does not mean that cable-stayed bridges are always more costly than pier and beam bridges in general. Cable-stayed bridges have other benefits that may outweigh their higher cost per unit area, such as longer spans, better aesthetics, lower maintenance costs, and faster construction times. Therefore, the choice between pier and beam bridges and cable-stayed bridges depends on many factors besides cost alone.

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