Cargo tiedowns

Scope

The requirements for cargo tiedowns apply to motor carriers and their commercial motor vehicle drivers.

Regulatory citations

• 49 CFR 393.102 — What are the minimum performance criteria for cargo securement devices and systems?
• 49 CFR 393.104 — What standards must cargo securement devices and systems meet in order to satisfy the requirements of this subpart?
• 49 CFR 393.108 — How is the working load limit of a tiedown, or the load restraining value of a friction mat, determined?
• 49 CFR Part 393, Subpart I — Protection against shifting and falling cargo

Key definitions

• Aggregate working load limit: The summation of the working load limits or restraining capacity of all devices used to secure an article of cargo on a vehicle.
• Anchor point: Part of the structure, fitting, or attachment on a vehicle or article of cargo to which a tiedown is attached.
• Article of cargo: A unit of cargo, other than a liquid, gas, or aggregate that lacks physical structure (e.g., grain, gravel, etc.) including articles grouped together so that they can be handled as a single unit or unitized by wrapping, strapping, banding, or edge protection device(s).
• Commercial motor vehicle: A self-propelled or towed vehicle used on a highway to transport property or passengers when the vehicle:
  • Has a gross vehicle weight rating (GVWR) or gross combination weight rating (GCWR), or gross vehicle weight (GVW) or gross combination weight (GCW), of 10,001 pounds or more, whichever is greater; or
  • Is designed or used to transport more than 8 passengers (including the driver) for compensation; or
  • Is designed or used to transport more than 15 passengers (including the driver), and not used to transport passengers for compensation; or
  • Is transporting hazardous materials of a type or quantity that requires placarding.
• Edge protector: A device placed on the exposed edge of an article to distribute tiedown forces over a larger area of cargo than the tiedown itself, to protect the tie-down and/or cargo from damage, and to allow the tiedown to slide freely when being tensioned.
• Tiedown: A combination of securing devices which forms an assembly that attaches articles of cargo to, or restrains articles of cargo on, a vehicle or trailer, and is attached to anchor point(s).
• Working load limit (WLL): The maximum load that may be applied to a component of a cargo securement system during normal service, usually assigned by the manufacturer of the component.

Summary of requirements

The cargo securement requirements of the Federal Motor Carrier Safety Regulations, found in Subpart I of 49 CFR Part 393, specify how — and how many — cargo tiedowns are to be used. Tiedowns include chains, ropes, webbing, steel straps, binders, buckles, and other devices that can be used to secure cargo. Tiedowns are obviously a very important part of a safe trucking operation, because they prevent the shifting or loss of cargo.

Working load limits (WLL). A key concept when working with tiedowns is their “working load limit” (WLL) which indicates how strong they are and thus how much cargo they can secure. The WLL is the maximum load that may be applied to a tiedown or other component of a cargo securement system during normal service. The WLL is usually assigned by the manufacturer of the component and is generally equal to 1/3 (or in some cases 1/4) of the ultimate breaking strength of that device.

The WLL of a tiedown, associated connector, or attachment mechanism is the lowest WLL of any of its components (including tensioner), or the WLL of the anchor points to which it is attached, whichever is less. For example, if a chain has a WLL of 6,600 pounds but the binder used on that chain has a WLL of 5,000 pounds, the WLL for that tiedown device is 5,000 pounds. This is based on the idea that the securement system is only as strong as its weakest component.

Determining the working load limit of a tiedown. The regulations do not require tiedowns to be marked or labeled. However, manufacturers of tiedowns and associated equipment are encouraged to provide motor carriers and enforcement officials with a means to easily determine the working load limits of their products.

The WLLs may be determined by using either:

• The tiedown manufacturer’s markings on the device, or
• The tables in 393.108.

The WLLs listed in the regulation must be used when the tiedown material is not marked with a WLL by the manufacturer. If the value in the regulation is different from the manufacturer’s marking, use the marked value.

Aggregate WLL. Another key factor when using tiedowns is their combined or “aggregate” working load limit. The aggregate WLL of any securement system must be at least ½ times the weight of the article(s) being secured. For example, the tiedowns used to secure cargo weighing 30,000 pounds must have an aggregate WL of 15,000 pounds. The aggregate WLL is determined by adding together:

• 1/2 the WLL of each tiedown that goes from an anchor point on the vehicle to an anchor point on an article of cargo;
• 1/2 the WLL of each tiedown that is attached to an anchor point on the vehicle, passes through, over, or around the article of cargo, and is then attached to an anchor point on the same side of the vehicle; and
• The full WLL for each tiedown that is attached to an anchor point on the vehicle, passes through, over, or around the article of cargo, and then attaches to another anchor point on the other side of the vehicle.

Use and inspection of tiedowns. Tiedowns and associated connectors and mechanisms (except steel strapping) must allow for in-transit adjustment, and en-route inspection of tiedowns is required.

• Tiedowns cannot be used if they have any knots.
• If a tiedown is repaired, it must be repaired in accordance with accepted manufacturing standards.
• Tiedowns must be attached and secured in a way that prevents them from becoming loose, unfastening, opening, or releasing while in transit.
• Edge protectors must be used whenever a tiedown would be subject to abrasion or cutting at the point where it touches an article of cargo.

The minimum performance criteria for tiedowns, based on forces of acceleration and deceleration, are found in 393.102.