Trench Proximity Calculator
Calculate the minimum safe distance for plant operating near open excavations, based on HSE guidance for different ground conditions.
Trench Proximity Calculator
HSG47Enter trench depth, pad width, and ground condition to calculate the minimum safe operating distance.
Results
Important Notes
Variables Explained
- h = depth of the excavation (trench) in metres
- d = width of the ground-bearing pad or timber mat in metres (reduces the required standoff)
- M = minimum distance from the nearest edge of the plant's bearing to the edge of the excavation
Stable / Firm Ground
The formula M = 2h - d applies when the ground is undisturbed, well-compacted, or naturally firm. Most typical construction sites with compacted fill or natural clay/gravel.
Soft / Waterlogged Ground
The formula M = 4h - d applies when the ground is soft, recently disturbed, waterlogged, or made-up ground. The safe distance doubles compared to stable ground.
HSE Reference
Based on HSE publication HSG47 — Avoiding danger from underground services and general excavation safety guidance. Always consult the site-specific risk assessment and method statement.
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