Federal rules put two separate cargo checks on you, and the knowledge test asks about both. The first is a single inspection of the cargo and its securement devices within the first 50 miles after you begin a trip. The second is a re-check that keeps repeating for the rest of the run.
After that 50-mile inspection, 49 CFR 392.9(b)(3) requires you to re-examine the load and make any needed adjustment whenever one of three things happens, whichever occurs first: you change your duty status, the vehicle has been driven for 3 hours, or the vehicle has been driven 150 miles.
Most state manuals phrase the same rule as "after 3 hours or 150 miles, and after every break." A break is a change of duty status, so the two versions describe one schedule. Learn the numbers in both forms, because either wording can turn up in a question.
The schedule, in the order it happens
- Before you move. You may not operate the vehicle unless the cargo is properly distributed and adequately secured, and it does not obscure your view, interfere with your movement, or block your access to emergency equipment.
- Within the first 50 miles. Stop and inspect the cargo and the devices holding it. Loads settle and straps stretch early in a trip, so this is the check that catches a tiedown that has gone slack.
- Every 3 hours, every 150 miles, or at any change of duty status, whichever comes first. Re-examine and adjust, including adding more securement if the load needs it.
Two exceptions are written into the rule. It does not apply to the driver of a sealed vehicle who has been ordered not to open it, or to a vehicle loaded in a way that makes inspecting the cargo impracticable. Sealed and containerized loads are also where you still have to satisfy yourself that you are inside the gross and axle weight limits, since you cannot see the load.
What "properly secured" means
Securement is a performance standard, not a preference. Cargo has to be firmly immobilized or secured by structures of adequate strength, dunnage or dunnage bags, shoring bars, tiedowns, or a combination of those.
The numbers behind that standard explain every rule that follows. A securement system has to hold the load through 0.8 g of deceleration forward, 0.5 g of acceleration rearward, and 0.5 g sideways. If the article is not fully contained by the vehicle structure, the system also has to press down on it with at least 20 percent of its weight. Forward is the largest figure, which is why blocking against forward movement changes how many tiedowns a load needs.
Tiedowns also have to stay usable. Each one must be built and maintained so the driver can tighten it while the vehicle is in transit, with steel strapping as the exception, and no tiedown may contain knots. Damaged or weakened components are out.
How many tiedowns a load needs
Your manual gives the short version: at least one tiedown for every 10 feet of cargo, and never fewer than two, no matter how small the load. That is the answer a knowledge test question is looking for.
The regulation, 49 CFR 393.110, is more specific, and roadside inspectors work from it. For an article that is not blocked or braced against forward movement:
- One tiedown if the article is 5 feet or less in length and 1,100 pounds or less in weight.
- Two tiedowns if it is 5 feet or less but heavier than 1,100 pounds, or if it is longer than 5 feet and up to 10 feet, at any weight.
- Two tiedowns if it is longer than 10 feet, plus one more for every 10 feet, or fraction of 10 feet, beyond the first 10.
So a 20-foot article that is not blocked needs three tiedowns under the regulation, where the manual's rule of thumb would give you two. When the article is blocked, braced, or immobilized against forward movement, the count drops to one tiedown for every 10 feet of length or fraction of it.
Answer test questions from your state manual. Load the truck from 393.110.
Working load limit and the one-half rule
Working load limit (WLL) is the maximum load that may be applied to a component of a securement system during normal service, usually assigned by the manufacturer. It is not breaking strength, and you never work to breaking strength.
Aggregate working load limit is the sum of the working load limits of every device securing the article. The rule is that the aggregate WLL of the system must be at least one-half the weight of the article or group of articles it secures. A 10,000-pound machine needs at least 5,000 pounds of aggregate WLL holding it.
How much each tiedown contributes to that total depends on how it is run:
- Half its WLL when it goes from an anchor point on the vehicle to an attachment point on the cargo.
- Half its WLL when it passes over, through, or around the cargo and returns to an anchor point on the same side of the vehicle.
- Its full WLL when it passes over, through, or around the cargo and attaches to an anchor point on the other side.
Take the WLL from the manufacturer's marking on the strap, chain, or binder. If a component is not marked, use the tables in 49 CFR 393.108; unmarked wire rope counts as one-fourth of its nominal strength.
Center of gravity, and the loads that need extra care
Height is the part people skip, and it is on the test. A high center of gravity, meaning cargo piled up or heavy cargo stacked on light, makes the vehicle more likely to tip over, and it is most dangerous in curves or if you have to swerve. Distribute the load as low as you can and put the heaviest parts under the lightest.
Some loads carry that problem built in. Dry bulk tanks sit high and the contents move. Hanging meat swings. Livestock lean into a curve and shift the center of gravity with them. All three call for slower entry into ramps and turns.
The front-end structure, the headache rack, is your last line of defense. It has to reach 4 feet above the deck or high enough to block forward movement of the cargo, whichever is lower, and be at least as wide as the vehicle or wide enough to block the load, whichever is narrower.
Practicing the cargo questions
Cargo securement on a general knowledge test is mostly recall: the intervals, the tiedown count, the one-half rule. CDL Prep Exam 2026: Permit runs these inside General Knowledge with an explanation after each answer, and flashcards for the numbers.
What to do next
Open Section 3 of your own state's CDL manual and read the cargo pages start to finish. States adapt the model manual, and weight limits and load-covering rules in particular vary from state to state. Then write the four numbers out from memory: 50 miles, 3 hours, 150 miles, one-half. Whichever one comes out fuzzy is the one a question will find.