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Difficulty: EasyCargo Securement: Tie-Down Rules and WLL

A commercial driver is loading an unblocked piece of machinery that is 6 feet long and weighs 18,000 pounds onto a flatbed trailer. The driver is using tie-down straps that each have a Working Load Limit (WLL) of 3,000 pounds. According to federal cargo securement regulations, what is the minimum number of tie-down straps required to safely secure this load?

  1. A
    1 strap
  2. B
    2 straps
  3. 3 strapsAnswer
  4. D
    6 straps

Answer

3 straps are required to safely secure the load.
Federal regulations mandate that cargo securement must satisfy both length rules and weight rules. Unblocked cargo 10 feet or shorter requires at least two tie-downs. In addition, the aggregate Working Load Limit (WLL) must equal at least 50% of the cargo weight (18,000 lbs×0.50=9,000 lbs18,000\text{ lbs} \times 0.50 = 9,000\text{ lbs}). With 3,000-pound straps, 3 straps provide an aggregate WLL of 9,000 pounds (3×3,000 lbs=9,000 lbs3 \times 3,000\text{ lbs} = 9,000\text{ lbs}), satisfying both the WLL threshold and the minimum tie-down count.

Step-by-Step Solution

1
Determine the minimum tie-down requirement based on cargo length and blocking status.
Minimum of 2 tie-downs required.
Federal cargo securement regulations require at least two tie-downs for cargo 10 feet or less in length that is not blocked or braced against a front-end header board.
2
Calculate the required aggregate Working Load Limit (WLL) based on cargo weight.
Required aggregate WLL = 9,000 pounds.
The aggregate WLL of all tie-downs combined must equal at least 50% (one-half) of the total cargo weight: 18,000 lbs×0.50=9,000 lbs18,000\text{ lbs} \times 0.50 = 9,000\text{ lbs}.
3
Calculate the number of straps needed to meet the aggregate WLL requirement.
3 straps (9,000 lbs/3,000 lbs=39,000\text{ lbs} / 3,000\text{ lbs} = 3).
Dividing the required 9,000-pound aggregate WLL by the 3,000-pound rating of each strap yields 3 straps.
4
Compare length-based and weight-based securement requirements.
3 straps.
The securement must satisfy both criteria simultaneously. Since 3 straps satisfy the 50% aggregate WLL requirement and exceed the 2-strap length minimum, 3 straps are required.

Key Concept

Cargo securement requires satisfying both length-based tie-down minimums (at least 2 for unblocked items 10 feet or shorter) and aggregate Working Load Limit requirements (at least 50% of the total cargo weight).
Estimated Time:45s
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Topics

Cargo Securement: Tie-Down Rules and WLL

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