A driver is transporting a single unblocked bundle of commercial timber on a flatbed trail… — Commercial Driver's License (CDL) General Knowledge Exam

A driver is transporting a single unblocked bundle of commercial timber on a flatbed trailer. The cargo measures $18\text{ feet}$ in length and has a total weight of $16,000\text{ pounds}$ . The driver is using indirect tie-downs (webbing straps passing over the cargo and anchoring on both sides of the trailer), each with a Working Load Limit (WLL) of $3,000\text{ pounds}$ . According to Federal Motor Carrier Safety Administration (FMCSA) cargo securement standards, what is the minimum number of tie-downs required to legally secure this load?

A
1 tie-down
B
2 tie-downs
3 tie-downsAnswer
D
6 tie-downs

Answer

3 tie-downs are required to legally secure the cargo.

Federal Motor Carrier Safety Administration (FMCSA) cargo securement standards require drivers to satisfy two independent criteria: cargo length and aggregate Working Load Limit (WLL). Based on length, an unblocked

18\text{-foot}

item requires at least 2 tie-downs (1 tie-down per

10\text{ feet}

or fraction thereof). Based on weight, the aggregate WLL must equal at least

50\%

of the total cargo weight (

0.50 \times 16,000\text{ lbs} = 8,000\text{ lbs}

). Two straps rated at

3,000\text{ lbs}

each provide only

6,000\text{ lbs}

of aggregate WLL, which is insufficient. Therefore, a minimum of 3 straps providing

9,000\text{ lbs}

of aggregate WLL is required to satisfy both regulations.

Step-by-Step Solution

Determine the minimum number of tie-downs required based on cargo length and blocking status.

For an unblocked article of cargo measuring

18\text{ feet}

, regulations require at least 1 tie-down for the first

10\text{ feet}

and 1 tie-down for each additional

10\text{ feet}

or fraction thereof, resulting in a minimum of 2 tie-downs.

Cargo securement rules specify a baseline number of tie-downs based on dimensions to prevent shifting and rotation.

Calculate the required aggregate Working Load Limit (WLL) based on total cargo weight.

\text{Required WLL} = 50\% \times 16,000\text{ lbs} = 8,000\text{ lbs}

Federal regulations mandate that the aggregate WLL of all securement devices must equal at least half of the total weight of the cargo.

Calculate the number of

3,000\text{-pound}

rated straps needed to meet the aggregate WLL requirement.

\frac{8,000\text{ lbs}}{3,000\text{ lbs/strap}} = 2.67\text{ straps} \rightarrow 3\text{ straps}

(aggregate WLL

= 9,000\text{ lbs}

Because tie-down counts must be whole numbers and satisfy both length and weight mandates, the larger requirement governs.

Key Concept

Tie-Down Rules and Aggregate Working Load Limit (WLL)

Estimated Time:1m 15s

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