Trench Box 101

At Pro Shore we work with trench boxes day in, day out. We have piles of them in our depot, and most of the staff here have worked in the industry for years. This means that we tend not to think about them too much. However, we are aware that there are people out there that possibly don’t know what trench boxes are, or what they do. At least not to the same extent that we do here at Pro Shore.

Therefore, we wanted to write a short piece purely on trench boxes, and answer some of our commonly asked questions.

What Does a Trench Box Do?

Trench boxes are vital pieces of safety equipment used in the construction industry. They are predominantly used by the ground works team when digging foundations, or installing sewers and underground cabling etc.

Proshore worksite

Trench boxes are primarily used to prevent cave-ins and do so by shoring up the edges of ditches making them a safe environment to work in. The importance of trench boxes cannot be overstated, along with emphasising the need to adhere to proper health and safety guidelines. This includes having a competent person inspect the shoring every day before work starts.

They key issues that trench boxes aim to tackle are:

  • Preventing the collapse of excavations
  • Protecting workers from falling or dislodging material
  • Preventing workers from falling into excavations by using barriers etc.

How does a Trench Box Work?

A trench box is a two-sided system that is used in manual excavation. They come in both aluminium and steel. They are relatively simple devices, by their very nature and the purpose they serve they have to be. Trench boxes are made up two sheets, called shields, and the spreaders. Spreaders are adjustable beams which run perpendicular to the sheets and function as braces to prevent collapse.

This obviously serves multiple purposes. The first is that by shoring the sides of the trench you are preventing a collapse and ensuring the workers safety. They also provide ease of access in an out of the excavation, both in daily practices and in times of emergency. They also serve to increase productivity. By enabling easy entrance and exit workers can save time getting in and out of the excavation and work confidently when they are in there.

Proshore worksite

Which Trench Box Should You Use?

As we just mentioned, trench boxes are available in both aluminium and steel as well as varying sizes. Deciding which you need takes into account a huge range of variables, and rather than trying to explain them all in this article we recommend you call us so we can discuss your needs and ascertain which product suits you best from there.

How Big Can They Go?

As they are simple structures, trench boxes can actually accommodate quite large excavations. ProShore’s Super Trench Box can be up to 3.3 metres wide and 5.5 metres deep with a Maximum Lateral Earth Pressure of 34kN/m2. At ProShore we can supply these either flat packed or ready assembled, straight for installation.

What Depth is a Trench Box Required?

If you’re figuring out when to use a trench box- if an excavation is more than 5 feet, or 1.5 metres deep, then shoring equipment is needed by legal requirement. In some instances, trenches shallower than this may also need shoring equipment installed if decided so by a competent person. Obviously as Pro Shore we always err on the side of caution. In certain conditions a single cubic metre of soil can weigh as much as 1.5 tonnes – it is no exaggeration to say that this weight could be fatal to a person. The only situation where the above is not applicable is if the trench is made entirely of stable rock. 

To find out more about or trench boxes, or any of the products that Pro Shore supplies simply follow this link. Alternatively, you can call our office and speak to any one of our experts. Call us now on 0845 003 8984 or contact us here.

Contact Us

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    • T: 0845 003 8984
    • E:
    • Bridge Works, Wakefield Road, Ossett, WF5 9AW

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