Swing Fall Geometry (Pendulum Drop and Arc)

Working off to the side of an anchor turns a fall into a pendulum, and the vertical clearance calculation never counted it. Offset 10 ft with the anchor 20 ft up is exactly 30 degrees off vertical: the worker drops an extra 2.68 ft just getting under the anchor and arrives at the bottom of the arc doing 13.1 ft/s SIDEWAYS. Adds the swing drop to the required fall-protection clearance, and flags the 30-degree guidance. Pure geometry - the strike, lanyard stretch, and SRL locking are not modeled.

swing angle = asin(X/L); swing drop = L - sqrt(L^2 - X^2) = L(1 - cos theta); speed at the bottom of the arc = sqrt(2 g h); arc travelled = L x theta; total clearance = base + swing drop.

Pendulum geometry - no standard claimed and no new constants. The 30-degree limit for keeping an anchor overhead is commonly given fall-protection guidance, reported as such rather than as a computed threshold.

The geometry is elementary trigonometry; the 30-degree guidance is published widely in fall-protection training material.

Estimate. AHJ and licensed professional govern.

Field names used by the API: horizontal_offset_ft, anchor_height_ft, base_required_clearance_ft, swing_angle_deg, swing_drop_ft, impact_speed_fps, arc_length_ft, total_required_clearance_ft

• Taut line, fixed anchor rigid pendulum about the anchor; no lanyard stretch or SRL payout modeledstated simplification
• Swing drop is additive added to the vertical required clearance, not substituted for itgeometry
• 30-degree guidance commonly published limit for keeping an anchor overhead; reported, not derivedfall-protection training guidance