How must cargo be secured to prevent it from shifting during transport?

FEDERAL CARGO SECUREMENT RULES (49 CFR Part 393.100-136) establish minimum requirements for securing cargo to prevent shifting, falling, or leaking during transport. GENERAL RULE: Cargo must be secured well enough that it can't shift or fall during normal braking, acceleration, and cornering, AND during emergency maneuvers. TIE-DOWN REQUIREMENTS: Minimum aggregate working load limit of all tie-downs must equal at least HALF THE WEIGHT of the cargo. For cargo 10 feet long or less: minimum 2 tie-downs. For cargo over 10 feet: additional tie-downs at approximately one per additional 10 feet. METHODS OF SECUREMENT: TIE-DOWNS — straps, chains, cables, ropes rated for the load; BLOCKING — wood or rubber blocks placed against cargo to prevent movement; BRACING — framework preventing cargo movement; FRICTION — non-slip mats between cargo and trailer floor; DUNNAGE — padding to prevent damage and reduce movement. CARGO INSPECTION: Inspect cargo before and after the first 50 miles and every 3 hours or 150 miles thereafter (or when stopping). Tie-downs loosen through vibration and must be re-tensioned. EXEMPT CARGO: Some cargo types have specific rules: flatbed with logs, metal coils, concrete pipe, auto-transport — each category has its own requirements. CONSEQUENCES: Unsecured cargo that falls and causes injury or death can result in criminal liability, loss of CDL, and massive civil judgments.