According to BS6031 Code of practice for earthworks, a trench is any excavation whose length greatly exceeds it width. They sometimes qualify under the Confined Spaces Regulations.
Incidents in trenches are not as common as falls from stepladders, but are often fatal. A typical small trench collapse will contain 800kg of soil, which is equivalent of 8 people sitting on your chest, you won’t be able to breathe and you won’t be able to dig yourself out. (more…)