How Does A Bridge Affect The Environment?

How does the environment a bridge is in effect how the bridge will withstand, even with the different pressures it faces everyday? Which environment is the best and safest place for a certain bridge? The answers to these questions involves researching different topics such as bridge types and different structures. It is important to research about different environments so the environment is simulated correctly. Environments would include a mountainous/rocky terrain, grasslands, ocean/river, canyon, and a desert type environment. Bridges are an immensely important part to roads and transportation. Most bridges are designed with a triangle type support. This provides very good support if the triangle method is used properly (Public Broadcasting
Service (PBS), 2001). The triangle method is using triangles as support on bridges, it is so effective because the triangles distribute the weight evenly, while a square or other shape would not. With bridges, there are different forces that could effect the bridge, such as strong winds causing a bridge to twist until the point of collapsing. Different forces include tension in support cables or other parts of the bridge, settlement load, and thermal load (PBS, 2001). Thermal load could be a problem because it makes the structure expand and shrink which causes the bridges beams and columns to change along with pulling on different parts of the bridge. Settlement load is another problem that could take place in a bridge’s environment. This is when the structure settles unevenly and can cause the bridge to sink and change shape. These all effect how a bridge will perform in the environment it is in. Along with forces, the material of the bridge is a very big factor in how the bridge can survive its surroundings or not. Many bridges use reinforced concrete or steel because they both are very strong materials and can withstand most conditions. (PBS, 2001). Cast iron is a good material, it is very strong in compression but will break without warning when there is tension. Wood is also a very good material when used in the triangle method although the wood will rot and break down over time. These materials and different ones each have strength, but would not be able to withstand well in certain environments. Before building a bridge it is important to think about how the bridge will effect the environment, animals, and plant life located within it (Levy, 2003).
This is something for which engineers have to plan when building the bridge. Similarly, in water habitats or wetlands it is important to consider how the bridge would impact the environment and inhabitants of the area. Engineers not only have to consider how the bridge will effect the environment, but also how the environment will effect the bridge, such as strong currents rocking the bridge, and weakening its supports (Levy, 2003). Another important role to consider is pedestrian safety, especially on bridges over canyons. Making sure that no rocks fall is also crucial as it will loosen the soil and could cause support beams to fail and collapse the bridge (National Park Service (NPS), 2015). Environmental conditions play a key role on bridges such as fog, wind, and fault lines. Wind can create major problems for bridges, especially if they are strong ones. It can twist bridges to the point of collapse or move supports out of place. If bridges are placed on a fault line, and the line happens to move it could cause the bridge to give
way. Wildlife is a very big problem in all environments. Animals can cause numerous troubles, which is why it is smart to research animal activity in the area before building (Singer, 2015). Not only could animals be a problem but it is probably smart to research if there are any special plants or herbs in that location where the bridge would go. A way to keep wildlife and plant life off of the bridges is to build walls or put gates around the bridge. This would prevent animals from walking across the bridge and plants would grow along the fence line. The gate would help keep the wildlife and plant life at the location safe. The safety of people could be a problem as well, no matter which environment the bridge is built.
Which is why engineers could instead research the soil and ground to find a better spot that is safer for the pedestrians and would cause less casualties (NPS, 2015). Other concerns would be for the people that are actually building the bridge. Such as in a water environment when having to dive down to drill holes for the bridges supports. People having to dive down to put drill holes for supports and swim through murky water, as well as the possibility of getting the wrong measurement (PBS, n.d.). When storms happen during the construction, or while the bridge is in use, the storms could cause problems for the pedestrians and construction workers on the bridge. An example of a disaster like this is a bridge collapse in western Canada. During construction the bridge collapsed, it was 175 feet above water and a steel span of the structure broke and gave way collapsing and killing 59 workers in the process. As to why the bridge collapsed, it could be the water had weakened the supports or the measurement of the drilling holes were placed wrong because it was hard to see while drilling the holes. This is why it is better to research the area where you are building to see if it is suitable for a
bridge. Will the environment a bridge is in effect how the bridge handles under different pressures? The material and design of the bridge plays a key role in how the bridge will handle under pressure and in that environment. A safe design and good material must be used in order for a bridge to withstand the pressure and forces. Wildlife and pedestrian safety is a big concern for bridges as well, both will decide if the bridge could accommodate humans and wildlife. From this research it could help engineers when building a bridge to know what to look for and how to build a safe bridge in the environment which it is being built.