Building design and construction is extremely detailed. Not only does every aspect of the building and road need to be designed in detail, but the build method needs to be carefully planned. Until all of the required structures of the building are in place, it can be difficult to ensure support. This is often solved with shoring. Excavation shoring is a method that temporarily shores, or props, the building foundation up, while work is being completed. Because excavation shoring is used to safely hold up the building, the following safety precautions and steps are a crucial part of the process.
Basic excavation shoring requirements
There are a few requirements for even the most basic of excavation shoring projects. Many of these requirements are set by OHSA to ensure safety of all workers and residents in the area. On a basic level, OHSA requires safe access and egress to all excavations, including ladders, steps, ramps, or other safe means of exit for employees working in trench excavations 4 feet (1.22 meters) or deeper. These devices must be located within 25 feet (7.6 meters) of all workers. Many trenches also require temporary road mats for transportation of vehicles to and from the excavation shoring trench.
Heavy duty shoring
Larger buildings and structures, such as bridges, usually require more advanced of excavation shoring. Take the construction of a bridge, for example. A bridge construction requires a lot of materials and must have the ability to hold thousands and thousands of tons of weight. In the meantime, the excavation shoring methods used need to be able to support much of this weight. The build of bridges also usually requires deeper shoring methods. It is important to understand the deeper excavation shoring requirements, as well.
Earth excavation to a depth of 2 feet (0.61 m) below the shield is permitted, but only if the shield is designed to resist the forces calculated for the full depth of the trench and there are no indications while the trench is open of possible loss of soil from behind or below the bottom of the support system. Not only is loss of soil important for safety of the construction workers, but it is important for preserving the Earth. Careful temporary road mats will also need to be placed in these areas, to prevent further damage.
Shoring box trench requirements
Trench boxes also have a few strict requirements. Trenches that are 5 feet (1.5 meters) deep or greater require a protective system, unless the excavation is made entirely in stable rock. Trenches that are 20 feet (6.1 meters) deep or greater require that the protective system be designed by a registered professional engineer or be based on tabulated data prepared and, or approved by a registered professional engineer. Because engineers often have more knowledge of the different layers of the Earth and how much weight it can handle, they are tasked with making the final safety decision for the trench boxes.
Additional trench box safety methods might be used including a modular trench shield. This is a shield that is placed directly into the excavation shoring box and blocks out the elements of the ground from the box. This can reduce some of the risks of falling debris and of the trench box collapsing in. Finally, the temporary road mats and access road construction might be used to direct roads away from the shoring boxes. Excessive pressure nearby could also cause problems.
Designing and building a new building or bridge is often a long process. During the actual construction, safety precautions need to be made to support the foundation and to protect workers. This is usually done with temporary road mats, access road areas, and trench boxes. Trench boxes come in all sizes and levels and have the ability to support different sized projects. OHSA carries minimum requirements for the design and safety of trench boxes to protect workers. Safety should always be priority when doing excavation shoring projects and using trench boxes as a means of safety.