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Digging Trenches and Trench Safety
One of the oldest, yet common, types of tasks carried out in construction and excavation is digging trenches. In the early days, prior to the World War II era, a trench was dug out by hand with a shovel. When the trenches were dug deep, the sides of the trench had to be shored or supported to prevent the trench walls from falling in. After World War II, innovative experimentations were made in regards to the backhoe, and with that, digging trenches as a profession faded away. The year 1950 brought with it the hydraulically actuated backhoe, which made it very possible to dig deep trenches in minimal amounts of time. With the backhoe on the scene, there was no need for workers to be inside of the trenches during digging, and therefore, there was no longer a need to shore or support the walls. When you think of trenches, all trenches have something known as "stand up time". Stand up time is the amount of time that elapsed from the time it was dug until it collapsed. This calculated time depends on certain factors, such as soil type, how much water is in the soil, the depth of the actual trench, weather condition and the condition of the soil. The calculated stand up time could be as little as zero seconds or as broad as several months, and often it is difficult to even predict. Prior to digging a trench, a sample of the soil should be taken to calculate and estimate its stand up time. Remember, soil conditions are varied from area to area; so, it may be different in the area that is only a short distance away from where a sample was taken. Once a trench has been successfully dug out, the team of workers goes into the trench and carry out whatever work they needed to do, such as laying pipes, placing telephone or cable lines, welding pipes or maybe installing valves. It is important to realize that if the walls of the trench are not supported, there is always a chance for a collapse, and this is extremely dangerous. On average, it has been recorded that 100 to 300 people in the United States alone have been killed in trench collapses. With this type of work, the public can become aware of industrial progress, and this may lead to negative side effects. Engineers have a responsibility to protect the public from certain types of side effects, which is a very controversial topic. This is why using a trench box on the job site helps ease the debate. The trench box is also referred to as the trench shield, and it is placed within the trench in order to help prevent safety failures from injuring workers. A trench box consists of two large steel plates that run parallel to the wall of the trench, as well as horizontal, which keeps the two plates apart. The lower edges of the trench box are set upon the bottom of the trench and the top edges extend above the top of the trench. The way it works is that the workers will stay between the plates of the trench box. This way if there happens to be a collapse of the trench, the workers will be in the trench box, and the collapsed dirt will be stopped by the outside of the trench box. The trench box is pulled along inside of the trench using a backhoe or other strong machine. Sometimes certain projects will need a large excavation, such as when digging the foundation for very tall buildings. Often, the support structure for the walls is specified in the plans. However, there is a problem, more often than not, of trench boxes not being utilized in cities. The problem can arise when water or sewer lines have to be installed or fixed, and there has been no specification for a trench box. It is often left up to the discretion of the contractor, and unfortunately, if a trench box is not used and an accident occurs, it could be dangerous. Remember, if you happen to be digging trenches or find yourself working in one, you should use your common sense and take your time. Trenches are not always a safe place to work. If an accident occurs, it could be a deadly one, especially when a trench box is not utilized. If at all possible, you should not be in the trench, and let the machines do all that type of work.
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