Cargo Securement Rules: Working Load Limits and Tiedowns

What Part 393 actually asks of you

Part 393 sets a performance standard first and a prescriptive one second. Cargo has to stay put when the truck brakes hard, accelerates, swerves or corners, and the securement system has to withstand those forces without the load shifting enough to affect vehicle stability or spilling onto the road. Everything else in the subpart exists to make that standard checkable at roadside.

That two-layer design matters at inspection. An officer can write a violation because you failed a specific counting or rating requirement, and can also write one because the load is visibly unsecured even when your tiedown count looks fine on paper. Meeting the arithmetic is the floor. A load that is moving is a problem regardless of what you counted.

The subpart also covers the condition of the equipment. A strap with a cut edge, a chain with a stretched link, a binder that will not hold tension, a bent or cracked anchor point on the trailer rail. Damaged components do not count toward your securement, which quietly turns a load you believe is compliant into a deficient one.

The working load limit arithmetic you do before you leave

Working load limit is the rated capacity of a tiedown component, marked on the device by the manufacturer. It is not breaking strength. Breaking strength is where the thing fails, and the working load limit sits below that, set so the device operates with a margin under real dynamic loads. Drivers who confuse the two overestimate their securement badly.

Every element in the path carries a rating, and the weakest one governs. A chain rated higher than the binder attached to it gives you the binder's number, not the chain's. The same applies to the anchor point on the trailer. If the rail fitting is rated below your strap, the fitting is your working load limit for that tiedown.

Read the markings rather than guessing from appearance. Two chains that look identical can carry different grades, and a strap's rating depends on width and construction. Unmarked components have no usable rating, which means they contribute nothing you can defend. Keep damaged and unmarked hardware off the truck entirely, because it always ends up in use on a bad day.

The aggregate working load limit rule

The aggregate rule is the one that catches people. You do not just need enough tiedowns by count, you also need the sum of their working load limits to reach a proportion of the cargo weight that Part 393 sets. Two calculations, both mandatory, and passing one of them does not excuse failing the other.

Half-value counting is where the errors happen. A tiedown that runs from the trailer over the load and down to the other side is counted differently from one that runs from an anchor point to a fitting on the article itself. Get the counting convention wrong and your total can be well short of the requirement while your paperwork looks tidy.

Do the sum against actual cargo weight, not nominal weight. Drivers work off a bill of lading figure that is sometimes rounded, sometimes stated per pallet, sometimes simply wrong. If the weight you secured to is lower than the weight you are hauling, your aggregate calculation was invalid from the moment the load was built.

Tiedown counts by article length and weight

The general rule keys off two things: how long the article is and how much it weighs. Part 393 sets a length threshold and a weight threshold, and the minimum number of tiedowns steps up as an article passes them. FMCSA publishes the current figures, and every driver hauling on open deck should be able to recite them without looking.

The count is a minimum, not a target. Meeting the minimum count while failing the aggregate working load limit still leaves you out of compliance, and the reverse is also true. Articles that are not blocked against forward movement carry different requirements from articles that are, which is why blocking and dunnage belong in the securement plan rather than in the afterthought pile.

Long articles and grouped articles cause most of the confusion. A bundle secured as a unit still has to hold as a unit, and if the bundling straps are what keeps the pieces together, those straps are part of your system and they get inspected. Count what you actually have, article by article, not what the load looked like last time.

Commodity-specific rules that override the general ones

Part 393 contains separate requirements for particular commodities, and where they apply they take priority over the general rules. Logs, dressed lumber, metal coils, paper rolls, concrete pipe, intermodal containers, vehicles being transported, flattened or crushed vehicles, roll-on containers and large boulders each have their own section written around how that specific load behaves in transit.

Metal coils are the classic example. How a coil is secured depends on whether the eye sits vertical, lengthwise or crosswise, because the failure mode changes with orientation. A driver who applies the general tiedown formula to a coil can end up compliant on arithmetic and badly wrong on the actual rule, which is a fast route to an out of service order.

Check whether a commodity rule exists before building the load, not after. The list is finite, and a driver hauling the same freight every week only has to learn one or two of them properly. Carriers hauling mixed freight need the reference in the cab, because the general rules feel authoritative right up to the point where they do not apply.

How a securement problem becomes an out of service order

Roadside inspection follows a defined procedure, and cargo securement sits in the part of it where an inspector can place a vehicle out of service. That means the truck does not move until the problem is fixed. The criteria are published by the Commercial Vehicle Safety Alliance and applied by the inspecting officer, so do not rely on a driver's read of what counts as minor.

What tends to trigger it is a system that has failed rather than a paperwork shortfall. Loose or missing tiedowns, cut webbing, a load that has shifted against the headboard, chains resting on a sharp corner without edge protection, an article that is not blocked where blocking was required. Those things are visible from outside the vehicle in seconds.

The cost is not only the enforcement action. It is a driver stuck on a shoulder restrapping a load he cannot safely reach, a delivery appointment missed, and a violation attached to the carrier's safety record that follows the fleet around. The penalty structure for securement violations is set by FMCSA, and current amounts come from the agency.

What online training covers and what it cannot

Online training handles the knowledge layer, and that is where most securement failures actually start. The performance standard, working load limit and aggregate arithmetic, the counting conventions, the commodity sections, the en route inspection duty and what an officer looks for are all learnable at a desk. At $49 it costs less than one restrapping delay on a shoulder.

What it cannot do is put hands on a chain. Throwing a strap over a high load, tensioning a binder safely, judging edge protection on a sharp corner and building blocking for an odd-shaped article are physical skills, and they have to be taught on your equipment with your freight. Pair the course with supervised loading before a new driver runs solo.

It also cannot cover your customers. Shipper loading practices, sealed trailers, dock rules about who straps what and your own procedure for refusing a load that cannot be secured are all internal matters. And no online course issues a DOT certification, because no such certificate exists. The employer qualifies the driver and holds the training record.

Who should take this course

Flatbed, step deck and lowboy drivers are the obvious group, and for them this is core trade knowledge rather than a compliance box. Van and reefer drivers need it too, since the same subpart governs freight inside a trailer, and a pallet that shifts in a dry van is a securement problem with exactly the same consequences at roadside.

Loaders, dock staff and warehouse supervisors who build loads should take it, because the driver signing for the load is often not the person who decided how it sits. When the dock understands why a driver is asking for another strap or refusing a load outright, the argument at the gate mostly stops happening.

Safety managers and new dispatchers benefit from the arithmetic even if they never touch a strap. A dispatcher who understands why a load takes longer to build stops pushing drivers to leave early, and a safety manager who can read a securement violation on a roadside report can tell a training gap from a one-off mistake.

Frequently asked questions