Transporting Cargo Safely
Transporting Cargo Safely tests securement, weight distribution, and the checks that keep a load legal. The exam expects you to know when a load needs more tie-downs, how to check them, and why axle weights matter as much as gross weight.
Weight limits
On Interstate highways the federal limits are 20,000 lb per single axle, 34,000 lb per tandem axle group, and 80,000 lb gross. Michigan legal loads and permit loads can differ, so check the Michigan CDL manual and permit rules for state roads. Overloading an axle makes steering and braking worse even if gross weight is legal.
Securement rules
- Cargo must be tied down with at least two tiedowns if it is longer than 5 feet or weighs more than 1,100 pounds.
- Use one tiedown for each 10 feet of cargo length, with a minimum of two.
- The combined working load limit (WLL) of all tiedowns must be at least 50% of the cargo weight.
- Recheck securement within the first 50 miles and every 150 miles or 3 hours thereafter.
Worked example
An 18,000 lb machine is 12 feet long. Minimum tiedowns: 12 ÷ 10 = 1.2, so 2; because it is over 1,100 lb and 5 feet, at least 2. Required aggregate WLL = 50% × 18,000 = 9,000 lb. If each tiedown is rated 2,500 lb WLL, four give 10,000 lb-enough; three give 7,500 lb-not enough. Four also satisfies the one-per-10-feet rule.
Traps
Counting tiedowns without adding their WLL; using a 4:1 safety factor incorrectly; forgetting the 50-mile recheck; and ignoring axle limits because the gross weight looks legal.