A Trench Box – A trench box is also known as a trench shield, sewer box, manhole box, or a tap box. It is used in the construction work. It provides stability to a trench and keeps the utility workers safe while they carry out their duties. It is a two sided support system used in a mechanical excavation.
A trench box is an important shoring equipment which is a boon for excavators. It helps to increase job safety as well as productivity. Workers use them while they pour the foundations. They also utilize trench boxes when they have to repair a piping or wiring underground. Trench boxes are extremely important for the construction industry.
The construction of new buildings or homes requires digging and excavation of the soil. So trench boxes are indispensable for the safety of the workers on the construction sites.
Trench boxes, also called trench shields or trench sheets, are one type of protective system. They aren’t designed to shore or prevent a trench wall from collapsing. Instead, they’re designed to protect workers from the pressure and weight of soil in the event of a cave-in.
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What is a trench box?
What is a Trench Box? A trench box is a safety device used to protect workers in trenches. It is a square structure made up of pre-constructed side sheets and adjustable cross members. It is usually made of steel or aluminum. Trench boxes are critical to the safety of workers working below ground as a trench collapse can be fatal.
Trench boxes may also be referred to as sewer boxes, manhole boxes, trench shields, trench sheets, or tap boxes. Workers in trench construction should take every precaution to prevent collapse and ensure safety. OSHA rules require trench boxes to protect workers involved in trenching and excavation. Anyone doing this work must follow specific standards of safety outlined in OSHA Safety and Health Regulations for Construction, Subpart P, titled “Excavations.” Trench boxes and other safety measures may also be required in insertion or reception pits of trenchless construction.
Trench boxes are usually constructed onsite using an excavator or other heavy-duty equipment. First, a steel or aluminum sidesheet is laid on the ground. Spreaders (usually four) are attached to the sidesheet. With the four spreaders extending vertically, another sidesheet is attached on top.
Then the structure is turned upright. Now rigging is attached to the box and it is lifted and placed into the trench. A guidewire may be used by a worker to align the trench box to the hole. The primary reason for a trench box is the safety of workers while they are in the trench. Trench shoring is a related term that refers to the process of bracing the walls of an entire trench to prevent collapse.
Companies doing this work are responsible for the safety of employees and are liable for any negligent mishaps. Synonyms Manhole Box, Sewer Box, Trench Shield, Trench Sheets, Tap Box Share this Term : What is a Trench Box?
How do you install a trench box?
Cutting Through Confusion – “Used appropriately, a trench box can help protect workers from serious and sometimes fatal injuries if a cave-in occurs,” said Shane Wareham, director of sales and marketing of, Too often, contractors misunderstand the right way to build and install a trench box, and some take shortcuts that put workers’ lives at risk, said Wareham.
“A seemingly small mistake with a trench box could have huge unforeseen consequences. When in doubt, contractors should always turn to experts to help keep workers safe.” In rules set for trench box applications, OSHA requires a protective system be used when trench depths reach 5 ft. or more. Protective systems also are required for trenches less than 5 ft.
deep if the soil could cave in when the trench is dug, according to United Rentals. “A competent person must evaluate the conditions and determine which type of protective system is needed.” Though not designed to prevent a trench wall from collapsing, trench boxes protect workers from the pressure and weight of soil in the event of a cave-in.
- These shielding devices are engineered to withstand great pressure from the earth that surrounds them, and are made from aluminum or steel construction in varying sidewall thicknesses Their walls are held apart by spreaders or panels to the desired width.
- The soil pressures and depth ratings on a trench box are determined by their designs.
In its 29 CFR Part 1926.650-.652 Subpart P-Excavations, OSHA includes these rules on the installation and use of trench boxes:
A contractor should install a trench box in a way that restricts its lateral movement if there’s a sudden load placed on it (for instance, the earth starts to cave in or shift). The space between the excavation side and the trench box should be backfilled to ensure that it’s as small as possible. The maximum distance between the bottom of the trench box and the bottom of the trench should be no more than 2 ft. A contractor can excavate up to 2 ft. under a trench box as long as there’s no indication that the soil is collapsing behind the shield or below it and the shield is rated for the full depth. A trench box can be used in combination with other protective systems, such as sloping and benching. Under that circumstance, the trench box must extend 18 in. above the vertical part of the excavation walls to keep dirt, rocks and other debris from rolling into the trench. If the top of the trench box is at ground level, however, the trench box does not have to extend 18 in. above grade. Trench boxes must be able to handle the pressure at the depth where they’ll be used and for the type of soil they’ll be used in. The competent person can use the manufacturers’ tabulated data to determine if a trench box is appropriate for a particular situation. If a trench is deeper than 20 ft., contractors must use a registered professional engineer (RPE) to design the trench box or select the right trench box for the depth of the excavation using manufacturer’s tabulated data. As trenches get deeper, trench boxes can be stacked on top of one another to provide the necessary protection for workers. Each trench box must be designed to resist the pressure of the earth at the level where it’s being used. Contractors don’t have to use the same trench boxes for the top or the middle of the stack that they’d use for the bottom. OSHA advises using some kind of designation system to differentiate the trench boxes when they’re going to be used in a stack. Workers can’t remain in the trench box when it’s being installed, taken out or moved vertically. According to OSHA Training Services Inc., the movement of the trench box can cause the soil on the sides of a trench to shift and cave in. Plus, a worker could be struck or crushed by the trench box as it is moved. “So relocate to another protected area of the trench as the trench box is being moved, or get completely out of the trench and stand in a safe place,” suggested the training organization. People working in a trench box must have access to a ladder or other means of egress. The ladder must be secured and located within 25 lateral ft. of all workers, and it must extend beyond the top of the trench by 3 ft.
OSHA Training Services stresses workers must not climb up and down the spreader pipes. 
“When using a portable ladder to enter or exit the trench, make certain it is located inside of the trench box or other protected area of the trench.” Secure the ladder against unintentional displacement, and make sure the side rails extend at least 3 ft. above the top of the ground or other landing surface “so you have something to grab when getting on and off of the ladder.”
If the workers are using a structural ramp as their egress, a “competent person” qualified in structural design has to design it.”Designating a competent person and making sure that person is adequately trained is one of the most important steps to preventing trench injuries and fatalities,” noted OSHA.In addition, OSHA requires employers “to train employees on the hazards they may be exposed to, how to protect themselves and what PPE is necessary to work safely.”Trench boxes are popular for their relative ease of installation and use compared to building a timber shoring system or other forms of protective system.But there are a few things OSHA Training Services instructors suggest contractors and workers keep in mind when utilizing a trench box as a protective system:
Never enter a trench box until you are certain the competent person has cleared it for entry. Never walk out of a trench box into an unprotected area of a trench for any reason, even if it is just for a few seconds. A cave-in can happen in a split second with little or no warning of what is about to occur. Be on the lookout for any missing parts or damage that may occur to trench boxes. “Broken welds, bent spreader pipes and missing retainer pins need to be reported as quickly as possible so they can be evaluated by the competent person and corrected when necessary.” Also report other conditions that may affect the safe function of trench boxes. For example, situations where the trench box has settled in the soil and the top of the trench box drops below ground level. Federal OSHA standards and many trench box manufacturers do allow excavation of soil up to 2 ft. below the bottom of a trench box, but only in certain conditions. “So do not excavate soil to a level below the bottom of a trench box without first confirming with the competent person it is safe to do so; and if so, confirm how deep you can dig,” stressed the training organization. CEG
: Trench Box Installations Require Knowledge of OSHA Safety Rules : CEG
How do you determine if a trench box is right for You?
Cutting Through Confusion – “Used appropriately, a trench box can help protect workers from serious and sometimes fatal injuries if a cave-in occurs,” said Shane Wareham, director of sales and marketing of, Too often, contractors misunderstand the right way to build and install a trench box, and some take shortcuts that put workers’ lives at risk, said Wareham.
- A seemingly small mistake with a trench box could have huge unforeseen consequences.
- When in doubt, contractors should always turn to experts to help keep workers safe.” In rules set for trench box applications, OSHA requires a protective system be used when trench depths reach 5 ft. or more.
- Protective systems also are required for trenches less than 5 ft.
deep if the soil could cave in when the trench is dug, according to United Rentals. “A competent person must evaluate the conditions and determine which type of protective system is needed.” Though not designed to prevent a trench wall from collapsing, trench boxes protect workers from the pressure and weight of soil in the event of a cave-in.
- These shielding devices are engineered to withstand great pressure from the earth that surrounds them, and are made from aluminum or steel construction in varying sidewall thicknesses Their walls are held apart by spreaders or panels to the desired width.
- The soil pressures and depth ratings on a trench box are determined by their designs.
In its 29 CFR Part 1926.650-.652 Subpart P-Excavations, OSHA includes these rules on the installation and use of trench boxes:
A contractor should install a trench box in a way that restricts its lateral movement if there’s a sudden load placed on it (for instance, the earth starts to cave in or shift). The space between the excavation side and the trench box should be backfilled to ensure that it’s as small as possible. The maximum distance between the bottom of the trench box and the bottom of the trench should be no more than 2 ft. A contractor can excavate up to 2 ft. under a trench box as long as there’s no indication that the soil is collapsing behind the shield or below it and the shield is rated for the full depth. A trench box can be used in combination with other protective systems, such as sloping and benching. Under that circumstance, the trench box must extend 18 in. above the vertical part of the excavation walls to keep dirt, rocks and other debris from rolling into the trench. If the top of the trench box is at ground level, however, the trench box does not have to extend 18 in. above grade. Trench boxes must be able to handle the pressure at the depth where they’ll be used and for the type of soil they’ll be used in. The competent person can use the manufacturers’ tabulated data to determine if a trench box is appropriate for a particular situation. If a trench is deeper than 20 ft., contractors must use a registered professional engineer (RPE) to design the trench box or select the right trench box for the depth of the excavation using manufacturer’s tabulated data. As trenches get deeper, trench boxes can be stacked on top of one another to provide the necessary protection for workers. Each trench box must be designed to resist the pressure of the earth at the level where it’s being used. Contractors don’t have to use the same trench boxes for the top or the middle of the stack that they’d use for the bottom. OSHA advises using some kind of designation system to differentiate the trench boxes when they’re going to be used in a stack. Workers can’t remain in the trench box when it’s being installed, taken out or moved vertically. According to OSHA Training Services Inc., the movement of the trench box can cause the soil on the sides of a trench to shift and cave in. Plus, a worker could be struck or crushed by the trench box as it is moved. “So relocate to another protected area of the trench as the trench box is being moved, or get completely out of the trench and stand in a safe place,” suggested the training organization. People working in a trench box must have access to a ladder or other means of egress. The ladder must be secured and located within 25 lateral ft. of all workers, and it must extend beyond the top of the trench by 3 ft.
OSHA Training Services stresses workers must not climb up and down the spreader pipes. “When using a portable ladder to enter or exit the trench, make certain it is located inside of the trench box or other protected area of the trench.” Secure the ladder against unintentional displacement, and make sure the side rails extend at least 3 ft. above the top of the ground or other landing surface “so you have something to grab when getting on and off of the ladder.”
If the workers are using a structural ramp as their egress, a “competent person” qualified in structural design has to design it.”Designating a competent person and making sure that person is adequately trained is one of the most important steps to preventing trench injuries and fatalities,” noted OSHA.In addition, OSHA requires employers “to train employees on the hazards they may be exposed to, how to protect themselves and what PPE is necessary to work safely.”Trench boxes are popular for their relative ease of installation and use compared to building a timber shoring system or other forms of protective system.But there are a few things OSHA Training Services instructors suggest contractors and workers keep in mind when utilizing a trench box as a protective system:
Never enter a trench box until you are certain the competent person has cleared it for entry. Never walk out of a trench box into an unprotected area of a trench for any reason, even if it is just for a few seconds. A cave-in can happen in a split second with little or no warning of what is about to occur. Be on the lookout for any missing parts or damage that may occur to trench boxes. “Broken welds, bent spreader pipes and missing retainer pins need to be reported as quickly as possible so they can be evaluated by the competent person and corrected when necessary.” Also report other conditions that may affect the safe function of trench boxes. For example, situations where the trench box has settled in the soil and the top of the trench box drops below ground level. Federal OSHA standards and many trench box manufacturers do allow excavation of soil up to 2 ft. below the bottom of a trench box, but only in certain conditions. “So do not excavate soil to a level below the bottom of a trench box without first confirming with the competent person it is safe to do so; and if so, confirm how deep you can dig,” stressed the training organization. CEG
: Trench Box Installations Require Knowledge of OSHA Safety Rules : CEG
What is an excavation box?
Types of Trench Box – Put simply, a trench box is a box which sits in a trench. It really is that simple. Of course, this is a very particular type of box – a robust, two sided support system that provides structural support during soil excavation – and a very particular type of trench, wherein the cavity walls must be near-perfectly vertical and completely secure.
Backhoe Trench Box Backhoe Drag Box Mini and Standard Trench Box Rolling Strut Trench Box Super Drag Box
These different types vary considerably in terms of both size and complexity, so it’s extremely important that excavators choose the right trench box type for their excavation project.
How to install a trench box?
- Remove the handrail panels.
- Place and compact backfill soil according to the trench box’s specifications.
- Backfill in stages while removing the shield.
- Use a four-leg chain around the lifting points to remove the box.
- Use a single chain on one corner at a time if the previous methods don’t work.
Do Trench Boxes have to be certified?
The Occupational Safety and Health Administration requires that a trench boxmust be used for all trenching or excavations five feet or greater in -depth. Should the trenchdepth exceed twenty feet, an OSHA trench boxrequirements stipulate a certified, professional engineer must design the trench box.
What are the different types of trench equipment?
- Manual Trenching Tools. The most basic trenching implements are manual tools such as trenching shovels and trenching hoes.
- Chain-Blade Trenchers. A chain-blade trencher features a straight,chainsaw-like blade with a rotating toothed chain.
- Wheel Trenchers.
- Edging Trenchers.
- Wire and Micro Trenchers.
- Ride-On Trenchers.
- Portable Trenchers.
What are Trench Boxes?
Trench boxes, also called trench shields or trench sheets, are one type of protective system. They aren’t designed to shore or prevent a trench wall from collapsing. Instead, they’re designed to protect workers from the pressure and weight of soil in the event of a cave-in.
