Excavations: why it matters
A trench collapse is sudden and usually fatal. A single cubic metre of soil weighs well over a tonne, so even a shallow trench can crush and suffocate someone before they can move.
Safe excavation means supporting the sides, keeping loads and people back from the edge, and finding buried services before you dig. Excavations must be inspected by a competent person.
Excavations revision notes
Excavation questions reward one instinct: never trust the ground. Support the sides, keep loads back from the edge, and find buried services before you dig. Learn why from the notes below and the answers become obvious.
Soil is deadly heavy
A cubic metre of soil weighs 1.5 tonnes or more. A fall of earth does not need to bury you completely to kill, pressure on the chest alone can stop you breathing.
Support the sides
Prevent collapse by shoring with trench boxes or props, or by battering or benching the sides back to a safe angle. Never rely on the soil simply holding up.
Stay out of unsupported trenches
Never enter an unsupported excavation, even briefly. Most trench deaths happen to people who stepped in for a quick job.
Find buried services
Strike a buried cable or gas main and the result can be fatal. Use service plans, a cable avoidance tool, and careful hand digging to locate services before machine digging.
Keep the edges clear
Keep spoil, materials and plant well back from the edge, the extra weight (surcharge) can trigger a collapse. Use stop blocks to keep vehicles away from the edge.
Inspect and access
A competent person must inspect the excavation at the start of each shift and after any event that could affect stability. Provide safe access, such as a secured ladder, and edge protection.
Hear a question in Polish
These questions turn on detail, when a trench must be supported, or why a permit to dig and a cable avoidance tool come before machine digging. Press Play in Polish below to hear a real question read aloud alongside the English.
Which of these should always be done before workers enter a trench?
Check the weather forecast
Perform a risk assessment
Complete a site survey
Review paperwork
Every wrong answer can also come with an AI explanation that points to the specific rule behind the correct answer, so you learn from each mistake instead of just memorising. Native Polish audio and AI explanations are two things you will not find on other CSCS practice sites.
Excavations quiz, five questions
Five excavations questions in the real CITB format. Watch for the ones on entering unsupported trenches, surcharge at the edge and striking buried services. Answer each one and it is marked straight away, with the reason it is right.
0 of 5 answered
Score: 0 / 5
Q1. What is the recommended way to protect the edges of an excavation?
Reveal explanation
Correct answer: B. Install a barrier
Barriers prevent people and vehicles from accidentally falling into the excavation.
Q2. What is the primary hazard in a confined space?
Reveal explanation
Correct answer: A. Limited access and egress
Confined spaces may have limited access which can complicate emergency exits.
Q3. Who is responsible for managing risks in excavation work?
Reveal explanation
Correct answer: A. The site manager
The site manager is responsible for overseeing and managing site risks including excavations.
Q4. How often should atmospheric testing be conducted in a confined space?
Reveal explanation
Correct answer: C. Before each entry
Testing should be done before each entry to ensure safe air quality levels.
Q5. What does 'shoring' refer to in excavation safety?
Reveal explanation
Correct answer: C. Preventing trench collapses
Shoring is used to provide support to prevent trench collapses.
Answer all five to see how you did on excavations
The real CITB test is 50 questions in 45 minutes, with a 45 out of 50 pass mark. Our free mock test uses the same format and needs no account.
Common mistakes
These excavation beliefs get people buried or electrocuted, not just marked wrong. Unlearn them before the test and before you step into a trench.
Mistake 1: “A shallow trench is safe to enter.”
Correct: Even a trench below head height can kill. A small fall of heavy soil can pin and suffocate you in seconds, so the sides must be supported or battered before anyone enters.
Mistake 2: “You can pile the spoil right at the edge.”
Correct: Spoil and plant at the edge add weight (surcharge) that can collapse the trench. Keep all materials, spoil and vehicles well back from the excavation edge.
Mistake 3: “If the plans show no services, just dig.”
Correct: Plans are often out of date or incomplete. Always scan with a cable avoidance tool and hand-dig trial holes to confirm before machine digging, because a strike can be fatal.
Related CSCS topics
Excavations bring together ground, buried services and site traffic risks. These related areas complete the picture: