Excavation has always been known as dangerous work. Workers in this industry have a far greater chance of being killed than general construction trades; hence shoring cages are used.
As a solution, standards were created that identify common hazards found when having individuals work in trenches. Each employer is responsible for ensuring that each excavation is free of identified and predictable hazards. To do this, employers must designate a representative to design, construct and maintain the work area so that they will be free of hazards. A person assigned to this role is known as the qualified person. A trench is an excavation that has a greater depth than its width measured at the bottom. Employees who work in trenches that are 5 feet deep must be protected from a cave-in (a mass of soil separated from the bank of a trench) by a trench protective system.
Trench Shoring vs. Shoring Cages
Trench shoring should not be confused with trench shielding. In the end, they both serve the same purpose, which is to protect but they also function in different ways of protecting. Shoring cages are designed to protect workers in the event of a collapse or cave-in, while trench shores are designed to prevent the collapse or cave-in from ever occurring. Because trench shores examine a way to prevent all potential hazards of a work area, it is viewed as the safer and better option, even though it is more time-consuming.
The soil inside of a trench can sometimes be of a type that has an unconfined strength. Meaning a type of soil that has insufficient strength to stand unsupported. A type of soil that tends to run or slough into the excavation as the trench is being dug and worked by the worker(s). An excavation is a work area is not is not considered a work area until the workers actually begin working.
This would be the point where the qualified person would review and make an assessment of the potential dangers of the type soil workers would have to work with. If known and/or predictable hazards are found, a trench box system must be in place prior to the start of any work by the workers.
Shoring Cages and the Qualified Person
The assessment done by the qualified person will determine what type of trench shoring boxes will be used. Shoring cages are a type commonly used.
Trench shoring is the process of securing the wall surfaces of a trench. Having this safety equipment is extremely important for the well-being and protection of the work area and workers as they work on projects that require them to work inside of deep trenches.
There are several methods of trench shoring. A common method is hydraulic shores.
Hydraulic shoring products are lightweight that utilize hydraulic pressure to support banks of excavation. As the hydraulic cylinders are pressurized against trench walls, pressure arcs will radiate from the center of the cylinder in many different directions. If nearby shores are located close enough for the arcs to intersect, pressure arches will be formed. These arches shore the banks. These pressure arches fan out into the banks; supporting the soil without the presence of sheeting.
Other methods of shoring cages are beam and plate and more solid boarding. However, hydraulic shoring works faster than these and tend to be the choice for larger excavations.
When it comes to safety in construction, the biggest danger is having a situation occur where workers become trapped in dirt and materials. Trench shoring was developed as a method to prevent these types of situations.