By Stuart Thomas, Chief Engineer BEng(Hons) MEng CEng MICE, Mabey Hire
Construction equipment tends to play a number of roles in keeping a site running smoothly. Take the humble trench box, for example, to understand how one piece of equipment can have a several jobs on a construction site – and how working safely and productively can actually be one and the same thing.
The top three reasons for using a trench box are:
Safety is the number one reason to use shoring equipment such as a trench box in excavations. Put simply, if you excavate a hole in the ground, the ground all around it becomes unstable and could collapse. Did you know that, depending on the type of ground, a cubic metre of soil can weigh more than 1.5 tonnes? That’s the equivalent of a mini excavator.
That kind of load falling on construction workers can easily result in the injury and loss of life of those within the excavation. According to the Health and Safety Executive (HSE), there were 38 deaths in the construction industry in 2017-18, and 12 per cent of those were as a result of people being trapped by something collapsing.
It's for very good reason that the HSE states in Regulation 22 of the CDM Regulations that ‘all practicable steps must be taken to prevent danger to any person, and to ensure that no excavation or part of an excavation collapses’. For certain types of excavation, a correctly installed trench box is vital to guarantee workers’ safety.
By making sure your trench is safe, you could also be saving yourself time. Some sites may batter or bench an excavation (which means create ‘steps’ out of the soil at the side or excavate the ground out on a gentle slope at each side so that the loose material isn’t vertically piled up). But the ground may still collapse if there’s nothing holding it back – a real safety issue, and it will have to be excavated out again. That means loss of time – something in short supply on a construction site. Plus with a trench box, the amount of material that needs to be removed is substantially less than a battered or benched excavation – so it’s quicker. It also means safe excavations can be carried out in constrained site environments with a trench box.
Mabey’s purpose is to help our customers deliver their projects more quickly, safely and efficiently, and all of those aspects have been taken into account when we designed our box range. We can cater for lots of different requirements. For example, Drag Boxes can be used in cohesive ground to allow quick installation of pipes and other underground services. Aluminium and Backhoe Boxes have been designed to be lightweight and to be installed by smaller plant equipment. Rolling Strut Boxes have panels that can move vertically independently from each other and have a maximum internal width of 6.7 metres and can be used as an alternative to trench sheets and hydraulic frames.
Trench Boxes are used for rapid shoring of trench runs. These, together with Drag Boxes and Manhole Boxes, provide a quick and easy way of holding the ground stable in a trench without the need to use any other shoring equipment.Find out more