DOT Weight and Size Limit Regulations 5 — Questions and Answers
Question 1: A lowboy trailer transporting construction equipment measures 16 feet wide. What must the carrier obtain before movement?
- An oversize/overweight special permit and possibly an escort vehicle (Correct answer)
- A standard commercial vehicle registration only
- A FMCSA operating authority waiver
- A state driver's license endorsement upgrade
Correct answer: An oversize/overweight special permit and possibly an escort vehicle
Any load exceeding the standard width limit requires a special oversize permit, and widths beyond certain thresholds require escort vehicles.
Question 2: What is the maximum length allowed for a semitrailer operating on the National Network under federal guidelines?
- 53 feet (Correct answer)
- 48 feet
- 57 feet
- 45 feet
Correct answer: 53 feet
Federal law requires states to allow semitrailers up to 53 feet in length on the National Network.
Question 3: Which scale reading method requires a vehicle to drive across a scale at a slow speed without stopping?
- Weigh-in-motion (WIM) (Correct answer)
- Static axle weighing
- Portable axle scale method
- Pit scale measurement
Correct answer: Weigh-in-motion (WIM)
Weigh-in-motion (WIM) technology measures vehicle weight while the truck moves across the sensor at low speed.
Question 4: When calculating axle weight violations, which axle configuration is subject to the 34,000-pound federal limit?
- Tandem axle (two axles spaced within 40 to 96 inches) (Correct answer)
- Single drive axle only
- Tridem axle group
- Steer axle combined with first drive axle
Correct answer: Tandem axle (two axles spaced within 40 to 96 inches)
A tandem axle group—two axles spaced 40 to 96 inches apart—is subject to the 34,000-pound combined weight limit.
Question 5: A vehicle's overall length exceeds 65 feet. Under most state rules, what device may be required on the rear?
- An oversize rear flag or marker light plus possibly an escort vehicle (Correct answer)
- An additional axle to spread the load
- A reflective orange triangle warning sign only
- An audible backup alarm system
Correct answer: An oversize rear flag or marker light plus possibly an escort vehicle
Vehicles exceeding length limits typically must display oversize markers and may require rear escort vehicles depending on state law.
Question 6: What does the term 'gross combination weight rating (GCWR)' refer to in the context of DOT weight regulations?
- The maximum combined weight of the towing vehicle plus any towed unit as specified by the manufacturer (Correct answer)
- The actual measured weight of a loaded combination vehicle at a weigh station
- The federal legal limit of 80,000 pounds for all combination vehicles
- The weight of the cargo only, excluding the tractor and trailer
Correct answer: The maximum combined weight of the towing vehicle plus any towed unit as specified by the manufacturer
GCWR is the manufacturer-specified maximum combined weight for a power unit and all towed units, and it cannot legally be exceeded.
Question 7: An inspector discovers a vehicle with axle spacings that technically pass the Bridge Formula but the gross weight is 82,000 lbs. What is the correct enforcement action?
- Issue an out-of-service or violation for exceeding the 80,000-pound gross weight limit (Correct answer)
- Allow the vehicle to proceed because the Bridge Formula is satisfied
- Require the driver to obtain a special overweight permit immediately
- Reduce the citation to a warning since the Bridge Formula was not violated
Correct answer: Issue an out-of-service or violation for exceeding the 80,000-pound gross weight limit
Both the Bridge Formula AND the 80,000-pound gross weight limit must be satisfied; exceeding gross weight is a violation regardless of axle spacing.
DOT Weight and Size Limit Regulations 5
A lowboy trailer transporting construction equipment measures 16 feet wide.
What must the carrier obtain before movement?