06 Bijzondere werkzaamheden
 >  Working safely in pits and trenches
Discussion > Talk to your colleagues about it!
  • Do you recognise the risks from everyday work?
  • Do you recognise the control measures?
  • Are these always taken?
  • What can be improved?

This toolbox is about working in and around trenches and pits. By going through this toolbox, you will know what the risks are. You will also know which control measures you need to take in order to prevent these risks:

Before you start digging, you know what the quality of the ground is like. When in doubt: Ask your line manager if the ground is contaminated. He can inform you if a ground investigation has been carried out and what the results were. The KLIC (Cables and Pipes Information Centre) report shows whether or not there are any cables or pipes in the ground. Once this has been established, you may start excavating the pit or trench. There are risks involved in excavation work. We will discuss what these risks entail.

There are two ways to excavate pits and trenches:

  • Excavating safely under a safe slope
  • Excavating safely with the use of a (trench) formwork (earth retaining structure)

Which method is applied depends on various circumstances and situations. The method is selected during the preparation stage and is based on:

  • the environment;
  • composition of the soil;
  • and the nature of the excavation.
Risks > What can happen?

During (excavation) works around and inside of the pit/trench, there is a risk of:

  • the slope (gradually) collapsing;
  • the formwork (earth retaining structure) collapsing;
  • falling into the pit/trench;
  • limited workspace;
  • coming into contact with objects (materials or tools) falling into the trench/pit;
  • rolling stock being moved too closely by the trench/pit and falling into it.

You can imagine what will happen in situations like these. There is a strong possibility of permanent injury due to falling, entrapment, getting buried by soil or suffocation. The latter two might result in death.

The main causes are:

  • An unsafe slope gradient (risk of collapsing);
  • The duration of the excavation. If it takes long, the soil will dry out and the slope might become instable (risk of collapsing);
  • Elevations near the pit/trench. These put a lot of pressure on the edges of the pit/trench (risk of collapsing);
  • Traffic moving too closely by the pit/trench and causing vibrations (risk of collapsing);
  • Soil water flowing into or towards the pit/trench, causing the soil to wash away and the slope to weaken (risk of collapsing);
  • Presence of soil water in the pit/trench (risk of collapsing);
  • Building materials (stone, sand) or tools that are lying on the edge of the trench and might slide into it (falling objects, entrapment);
  • The lack of guard rails around the pit/trench (risk of falling);
  • An unsafe entrance into the trench/pit;
  • Limited escape options (in case of an emergency)

Driving direction       Angle              Excavation

Trench cordoned off with traffic shields
Unsafe work situation