A 5-axle tractor-semitrailer combination is operating on an interstate highway. The power … — Commercial Driver's License (CDL) General Knowledge Exam

A 5-axle tractor-semitrailer combination is operating on an interstate highway. The power unit has a manufacturer Gross Combination Weight Rating (GCWR) of $80{}000\text{ lbs}$ , a steering axle GAWR of $12{}500\text{ lbs}$ , and a drive tandem GAWR of $40{}000\text{ lbs}$ . The semitrailer has a tandem axle GAWR of $40{}000\text{ lbs}$ . When weighed at an official weigh station, the platform scale records the following actual weights:

- Steering axle: $11{}200\text{ lbs}$
- Drive tandem axle: $35{}600\text{ lbs}$
- Trailer tandem axle: $31{}700\text{ lbs}$

Which of the following statements correctly evaluates the legal compliance of this vehicle under federal highway weight limits?

A
The vehicle is operating legally because the total combination weight of $78{}500\text{ lbs}$ is below the $80{}000\text{ lbs}$ federal maximum gross limit and within the manufacturer GCWR.
B
The vehicle is operating legally because the drive tandem load of $35{}600\text{ lbs}$ does not exceed the manufacturer drive tandem GAWR of $40{}000\text{ lbs}$ .
The vehicle is overloaded because the drive tandem axle exceeds the federal limit of $34{}000\text{ lbs}$ , despite total gross weight and manufacturer ratings being within limits.Answer
D
The vehicle is overloaded because the total combination weight exceeds the legal sum allowed for a combination vehicle with three axle groups.

Answer

The vehicle is overloaded because the drive tandem axle exceeds the federal limit of

34{}000\text{ lbs}

, despite total gross weight and manufacturer ratings being within limits.

Federal regulations impose two independent weight constraints: total gross combination weight (maximum

80{}000\text{ lbs}

) and individual axle group weights (maximum

20{}000\text{ lbs}

for a single axle and

34{}000\text{ lbs}

for a tandem axle). Additionally, drivers must not exceed manufacturer ratings. In this scenario, while total weight (

78{}500\text{ lbs}

) is legal and manufacturer ratings are not exceeded, the drive tandem weight of

35{}600\text{ lbs}

exceeds the statutory tandem limit of

34{}000\text{ lbs}

1{}600\text{ lbs}

, making the vehicle illegal to operate without adjusting the load or sliding the fifth wheel/tandems.

Step-by-Step Solution

Calculate the actual Gross Combination Weight (GCW) by summing all axle scale weights.

Gross Combination Weight =

11{}200\text{ lbs} + 35{}600\text{ lbs} + 31{}700\text{ lbs} = 78{}500\text{ lbs}

Determines whether the total weight is within the federal statutory gross limit of

80{}000\text{ lbs}

and the manufacturer GCWR of

80{}000\text{ lbs}

Compare individual axle scale weights against standard federal axle limits (

20{}000\text{ lbs}

single axle,

34{}000\text{ lbs}

tandem axle).

Steering axle (

11{}200\text{ lbs} \le 20{}000\text{ lbs}

): legal; Trailer tandem (

31{}700\text{ lbs} \le 34{}000\text{ lbs}

): legal; Drive tandem (

35{}600\text{ lbs} > 34{}000\text{ lbs}

): overloaded by

1{}600\text{ lbs}

A commercial motor vehicle must comply with both gross limits and individual axle group limits.

Differentiate between manufacturer ratings (GAWR/GCWR) and statutory legal road limits.

Although the drive tandem weight (

35{}600\text{ lbs}

) is below the manufacturer GAWR of

40{}000\text{ lbs}

, highway law enforces the more restrictive

34{}000\text{ lbs}

limit.

A vehicle cannot legally operate above statutory limits regardless of higher manufacturer ratings.

Key Concept

Compliance with federal weight limits requires satisfying both total gross combination limits (

80{}000\text{ lbs}

) and individual axle limits (

20{}000\text{ lbs}

single,

34{}000\text{ lbs}

tandem), where the lower of statutory limits or manufacturer ratings governs.

Estimated Time:2m 0s

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