Trench shields (also called trench boxes or trench sheets) are steel or

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It h ...

structures used for protecting utility workers while performing their duties within a

trench A trench is a type of excavation or in the ground that is generally deeper than it is wide (as opposed to a wider gully, or ditch), and narrow compared with its length (as opposed to a simple hole or pit). In geology, trenches result from ero ...

and avoid

cave-ins A cave-in is a collapse of a geologic formation, mine or structure which may occur during mining, tunneling, or steep-walled excavation such as trenching. Geologic structures prone to spontaneous cave-ins include alvar, tsingy and other l ...

. They are customarily constructed with sidewalls of varying thicknesses held apart by steel or aluminum spreaders. Spreaders can be interchanged to match the width of the trench. The different materials and building designs lead to a variety of depth ratings: the depth of a trench that the shield can withstand a collapse without buckling. Depth ratings are determined by registered

professional engineer Regulation and licensure in engineering is established by various jurisdictions of the world to encourage life, public welfare, safety, well-being, then environment and other interests of the general public and to define the licensure process thro ...

s. A shield should not be confused with a shore. While they may serve the same function,

trench shoring Trench shoring is the process of bracing the walls of a trench to prevent collapse and cave-ins. The phrase can also be used as a noun to refer to the materials used in the process. Several methods can be used to shore up a trench. Hydraulic ...

is a different physical application that holds up the walls of a trench to prevent collapse. In the US, use of a trench shield is governed by OSHA 29 CFR Part 1926.650-.652 Subpart P-Excavations.

External links

National Utility Contractors Association

References

{{reflist Building engineering Protective barriers