Shoring Design Calculator

This calculator determines OSHA-compliant trench shoring requirements from trench depth, soil type, width, and length. Soil Type has the largest effect on both Max Lateral Pressure and Lateral Force per LF, more than a realistic change in Trench Depth alone -- OSHA's soil classification sets the lateral earth pressure coefficient (Ka) used in the Rankine active pressure formula, running from 0 for Stable Rock (a vertical cut needs no lateral support) up to 0.67 for Type C soil (loose sand and gravel, the least stable), so switching from Type A clay to Type C sand roughly doubles the lateral pressure at the same depth. Trench Depth also raises both pressure outputs, and it does so twice over in Lateral Force per LF, since depth enters that formula both directly and through Max Lateral Pressure.

Shoring Required flips from "No" to "Yes" right at 5 ft of trench depth -- OSHA's own threshold for when protective systems become mandatory, unless the soil is Stable Rock, which never requires shoring regardless of depth. Slope Ratio is read directly from the selected Soil Type and never responds to trench dimensions. Shoring Type Code also starts from Soil Type, but it isn't purely soil-driven: it steps up once Trench Depth passes roughly 10 ft (12 ft in this calculator), moving from the aluminum-hydraulic recommendation to sheet pile at the same soil type.