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Difficulty: MediumCargo Securement: Tie-Down Rules and WLL

A flatbed trailer is loaded with an unblocked crated industrial chiller unit measuring 14 feet14\text{ feet} in length and weighing 26,000 pounds26,000\text{ pounds}. If each synthetic webbing strap used for securement has a Working Load Limit (WLL) of 4,000 pounds4,000\text{ pounds}, what is the minimum number of straps required under federal cargo securement regulations?

  1. A
    3 straps
  2. B
    2 straps
  3. 4 strapsAnswer
  4. D
    7 straps

Answer

4 straps
Federal Motor Carrier Safety Administration (FMCSA) cargo securement standards require that the aggregate Working Load Limit (WLL) of all tie-downs equals at least 50% of the total cargo weight (26,000 lbs×0.50=13,000 lbs26,000\text{ lbs} \times 0.50 = 13,000\text{ lbs}). With each strap rated at 4,000 lbs4,000\text{ lbs}, dividing 13,00013,000 by 4,0004,000 yields 3.253.25, necessitating 4 straps (16,000 lbs16,000\text{ lbs} total WLL). Because 4 straps also exceeds the length-based requirement of 3 tie-downs (2 for the first 10 ft10\text{ ft} plus 1 for the remaining 4 ft4\text{ ft}), 4 straps fully satisfies all federal requirements.

Step-by-Step Solution

1
Determine the minimum number of tie-downs required by cargo length.
3 tie-downs required by length.
Federal regulations mandate at least 2 tie-downs for the first 10 feet10\text{ feet} of unblocked cargo length, plus 1 additional tie-down for every additional 10 feet10\text{ feet} or fraction thereof (14 feet14\text{ feet} total requires 2+1=32 + 1 = 3 tie-downs).
2
Calculate the required aggregate Working Load Limit (WLL) based on cargo weight.
Required aggregate WLL is 13,000 pounds13,000\text{ pounds}.
The aggregate WLL of all securement devices must equal at least 50%50\% of the cargo's total weight: 0.50×26,000 pounds=13,000 pounds0.50 \times 26,000\text{ pounds} = 13,000\text{ pounds}.
3
Calculate the number of 4,000 lb4,000\text{ lb} WLL straps needed to meet the aggregate WLL requirement.
4 straps required for strength.
13,000 pounds÷4,000 pounds/strap=3.25 straps13,000\text{ pounds} \div 4,000\text{ pounds/strap} = 3.25\text{ straps}, which rounds up to 4 complete straps (4×4,000 lbs=16,000 lbs≥13,000 lbs4 \times 4,000\text{ lbs} = 16,000\text{ lbs} \ge 13,000\text{ lbs}).
4
Apply the governing requirement between length and weight.
4 straps are legally required.
Cargo securement must satisfy both length rules and weight rules simultaneously; therefore, the higher minimum (max⁡(3,4)=4 \max(3, 4) = 4) governs.

Key Concept

Cargo securement requires satisfying both the length-based tie-down minimums and the aggregate Working Load Limit (at least 50% of cargo weight).
Estimated Time:1m 0s
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Topics

Cargo Securement: Tie-Down Rules and WLL

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