Catch Berm Width Checker
Estimates the rockfall catch-berm (catch-bench) width needed to contain falling rock using the modified-Ritchie empirical guideline, and checks a proposed width against it. For mine geotechnical engineers and ground-control planners.
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Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the bench height H.
- Optionally enter the actual or proposed berm width W to get a pass/fail verdict.
- Read the recommended width W_rec = 0.2H + 4.5 m, and the margin or shortfall if you supplied W.
How it works
The modified-Ritchie criterion (as popularised by Ryan & Pryor) sizes a catch bench to intercept and retain rock falling from the face above using a simple linear rule: W_rec = 0.2·H + 4.5 metres, with H the bench height.
It is an empirical containment guideline, not a trajectory analysis — it does not model bounce, roll-out distance or ditch geometry. If a proposed width W is entered, the tool compares it against W_rec and reports whether it meets the guideline and by how much it falls short.
Worked example
15 m bench, proposed 6.5 m berm. W_rec = 0.2×15 + 4.5 = 7.5 m. A proposed 6.5 m berm is 1.0 m below the guideline, so the verdict is 'Below guideline — widen'.
Common mistakes
- Treating the empirical width as a substitute for a rockfall trajectory simulation on high or benched slopes.
- Applying it blindly where local mine standards specify a different rule (e.g. 0.2H+2 m or site curves).
- Confusing the rockfall catch-berm with the geometric berm needed for a target overall angle.
Frequently asked questions
What is the modified Ritchie catch-berm rule?
A widely used empirical guideline for open-pit catch benches: recommended width = 0.2 × bench height + 4.5 m, descended from Ritchie's original ditch/berm criteria and updated by Ryan & Pryor.
Is 0.2H+4.5 a code requirement?
No — it is a rule of thumb. Regulators and mining companies set their own ground-control standards, so always check your site's slope design criteria.
Does this account for rockfall bounce and roll-out?
No. It is a static width guideline. For critical or high slopes, run a rockfall trajectory analysis to confirm containment.
How is it different from the Berm Width Calculator?
The Berm Width Calculator sizes the berm to achieve a target overall slope angle (geometry). This checker sizes it to catch rockfall (containment) — the two can give different widths.
Related tools
- Berm Width Calculator
- Overall Slope Angle Calculator
- Kinematic Wedge Intersection Calculator
- RQD Calculator
- Bench Face Height Calculator
- Wedge Failure Kinematic Screen
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