Section 3: Transporting Cargo

This section is for all commercial drivers

This section is about cargo safety. You must pass a written test on cargo safety to get a commercial driver license.

If you load or secure cargo incorrectly, it can be a danger to others and yourself. Loose cargo that falls off a vehicle can cause traffic problems and others could be hurt or killed. Loose cargo can hurt or kill you during a quick stop or collision. Your vehicle can be damaged by an overload. Steering can be affected by an improperly loaded vehicle making it more difficult to control.

Whether or not you load and secure the cargo yourself, you are responsible for:

  • Inspecting cargo.
  • Recognizing overloads and poorly balanced weight.
  • Ensuring that the cargo is securely tied down and covered, if applicable.

If you intend to carry hazardous materials or wastes that require placards or markings on your vehicle, you will also need a HazMat endorsement.

Inspecting Cargo

As part of your pre-trip inspection, check for overloads, poorly balanced weight, and cargo that is not secured correctly.

Inspect the cargo and its securing devices again within 25 miles after beginning a trip. Make any adjustments needed. Check the cargo and securing devices as often as necessary during a trip to keep the load secure. Inspect again:

  • After you have driven for three hours or 150 miles, whichever comes first.
  • After every break you take during driving.

Federal, state, and local regulations of weight, securement, cover, and truck routes vary greatly from place to place. Know the regulations where you will be driving.

Cargo Weight and Balance

You are responsible for making sure that the vehicle is not overloaded. Here are some definitions you should know:

Gross vehicle weight (GVW). The total weight of a single vehicle including its load. Gross combination weight (GCW). The total weight of a combination of vehicles including the load.

Gross vehicle weight rating (GVWR). The maximum weight rating specified by the manufacturer for a single vehicle including its load.

Gross combination weight rating (GCWR). The total GVWRs for the power unit and any towed vehicles. (This is not the same as the GVWR specified by a manufacturer for the towing capacity of a vehicle.)

Axle weight. The weight on the ground at one or more sets of axles.

Tire load. The maximum safe weight rating a tire can carry at a specified pressure. This rating is stated on the side of each tire.

Suspension systems. Suspension systems have a manufacturer's weight capacity rating.

Coupling device capacity. Coupling devices are rated for the maximum weight they can pull and/ or carry.

Legal Weight Limits

Weights must be kept within legal limits. States have maximums for GVWs, GCWs, and axle weights. Often, maximum axle weights are set by a bridge formula which permits less axle weight for axles that are closer together. This is to prevent overloading bridges and roadways.

Overloading can have bad effects on steering, braking, and speed control. Overloaded trucks have to go very slowly on upgrades. Worse, they may gain too much speed on downgrades. Stopping distance increases. Brakes can fail when forced to work too hard.

During bad weather or in mountains, operating at legal maximum weights may not be safe. Take this into account before driving.

Avoid Top-Heavy Loads

The height of the vehicle's center of gravity is very important for safe handling. A high center of gravity (cargo piled up high, or heavy cargo on top) means you are more likely to roll, especially on curves or if you have to swerve to avoid a hazard. It is very important to distribute cargo so the center of gravity is as low as possible. Load the heaviest parts of the cargo first or on the bottom.

Balance Cargo Weight

Poor weight balance can make vehicle handling unsafe. Too much weight on the steering axle can cause hard steering and can damage the steering axle and tires. Underloaded front axles (caused by loading weight too far to the rear) can make the steering axle weight too light to steer safely. Too little weight on the driving axles can cause poor traction, so that during bad weather, the truck may not be able to keep going. Weight that is loaded with a high center of gravity has a greater chance of rollover. On flatbed vehicles, there is also a greater chance that the load will shift to the side or fall off. Figure 3-1 shows examples of the right and wrong way to balance cargo weight.

diagrams of vehicles balancing cargo weight, right and wrong

Securing Cargo

Blocking is used in the front, back, and/or sides of a piece of cargo to keep it from sliding. Blocking is shaped to fit snugly against cargo. It is secured to the cargo deck to prevent cargo movement. Bracing is also used to prevent movement of cargo. Bracing goes from the upper part of the cargo to the floor and/or walls of the cargo compartment.


On flatbed trailers or trailers without sides, cargo must be secured to keep it from shifting and falling off. In closed vans, tiedowns can also be important to prevent cargo shifting that may affect the handling of the vehicle. Tiedowns must be of the correct type and strength. The combined strength of all cargo tiedowns must be strong enough to lift one and one half times the weight of the piece of cargo tied down. Proper tiedown equipment must be used, including ropes, straps, chains, and tensioning devices (winches, ratchets, cinching components). Tiedowns must be attached to the vehicle correctly (hook, bolt, rails, rings).

Cargo should have two tiedowns in the first 10 feet of cargo, and one tiedown every 10 feet thereafter. Make sure you have enough tiedowns to meet this need. No matter how small the cargo, it should have at least two tiedowns holding it.

Rules governing the loading and securement of logs, dressed lumber, metal coils, paper rolls, concrete pipe, intermodal containers, automobiles, heavy vehicles, flattened or crushed vehicles, Roll-On/Roll-Off containers, and large boulders are contained in the Code of Federal Regulations, Title 49, §393.

Covering Cargo

There are two basic reasons for covering cargo:

  1. To protect people from spilled cargo.
  2. To protect the cargo from weather.

Spill protection is a safety requirement in many states. Be familiar with the laws in the states where you will be driving.

You should look at your cargo covers in the mirrors often while driving. A flapping cover can tear loose, uncovering the cargo and possibly block your view or someone else's.

Spilling loads and damage to highway. It is against the law to operate on the highway a vehicle which is improperly covered, constructed, or loaded so that any part of its contents or load spills, drops, leaks, blows, sifts, or in any other way escapes from the vehicle. Exception: clear water or feathers from live birds (CVC §§23114 and 23115).

Any vehicle transporting garbage, trash, rubbish, ashes, etc., must have the load covered to prevent any part of the load from spilling on to the highway. Aggregate material must be carried in the cargo area of the vehicle and be six inches below the upper edge. The cargo area must not have any holes, cracks, or openings which could allow the material to escape. The vehicle used to transport aggregate material must be equipped with seals on any openings used to empty the load, splash flaps behind every tire or set of tires, and fenders. Other requirements are listed in CVC §23114. This does not apply to vehicles carrying wet waste fruit or vegetable matter, or waste from food processing plants.

Any person who willfully or negligently damages any street or highway is liable for the cost of repairing the road or any sign, signal, guard rail, or other facility that is damaged. The liability may include the cost of removing debris from the roadway.

Header Boards

Front end header boards ("headache racks") protect you from your cargo in case of a collision or emergency stop. Be sure the front end structure is in good condition. The front end structure should block the forward movement of any cargo you carry.

Sealed and Containerized Loads

Containerized loads generally are used when freight is carried part way by rail or ship. Delivery by truck occurs at the beginning and/or end of the journey. Some containers have their own tiedown devices or locks that attach directly to a special frame. Other containers (following the regulations established by the CHP) have to be loaded onto flatbed trailers. They are secured with tiedowns just like any other large cargo. You cannot inspect sealed loads, but you should check that you do not exceed gross weight and axle weight limits and that the seal is not broken.

Handling Other Cargo

Dry bulk tanks require special care because they often have a high center of gravity and the load can shift. Be extremely cautious going around curves and making sharp turns.

Hanging Meat

Hanging meat suspended in a refrigerated truck can be a very unstable load with a high center of gravity. Particular caution is needed on sharp curves such as offramps and onramps. Go slowly.


Livestock can move around in a trailer. This shifts the center of gravity and makes rollover more likely. With less than a full load, use false bulkheads to keep livestock bunched together. Even when bunched, special care is necessary because livestock can lean on curves.

Oversized Loads

Overlength, overwidth, and/or overweight loads require Caltrans transit permits. Driving is usually limited to certain times of the day. Special equipment may be necessary such as "wide load" signs, flashing lights, flags, etc. Such loads may require a police escort or pilot vehicles bearing warning signs and/or flashing lights. These special loads require special driving care.

Special Markings Needed

Any vehicle and load over 80 inches must, in addition to required vehicle lighting, show an amber combination clearance and side-marker lamp on the side of the load projection at the front and show a red combination clearance and side-marker lamp on the side of the projection at the rear.

Alternatively, if the overwidth of the projection does not extend more than three feet from front to rear at least one amber combination clearance lamp must be visible front, side, and rear at the extreme width, if the projection is near the front of the vehicle. If the projection is near the rear, at least one red combination side clearance lamp must be displayed (CVC §25100).

Projecting Loads

Lights (or flags) on projecting loads. When the load on any vehicle extends 4 feet (48 inches) or more beyond the rear of the body, a solid red or fluorescent orange flag at least 12 inches square must be placed at the extreme end of the load. If the vehicle is operated during darkness, there must be two lit red lights at the end of the load visible at a distance of 500 feet to the side and rear of the vehicle (CVC §24604).

A load extending one foot or more to the left on any vehicle must have an amber light on the extreme left side of the load. It must be visible at least 300 feet to the front and rear during darkness. If the load extends more than 120 inches, there must be an amber lamp at the front and a red lamp at the rear visible at least 300 feet.

If the vehicle is wider than 102 inches, a red or fluorescent flag not less than 12 inches square must be displayed at left front and left rear during daylight (CVC §25104).

Piggyback Trailers

When any trailer is loaded upon another vehicle (piggyback) to be moved on any highway, the trailer must be securely bound to the vehicle to prevent the trailer from shifting, toppling over, or becoming unstable.

Section 2: Driving Safely | Table of Contents | Section 4: Transporting Passengers Safely