Transporting oversize cargo (also called out of gauge or OOG cargo) is a highly specialized discipline. If you don’t understand the process in detail, you could end up wasting a lot of time and money, and maybe even breaking the law. Here are six big mistakes to avoid when you’re shipping OOG cargo. We’ve divided them into over-the-road trucking and ocean freight issues.

What is OOG shipping?

Out of gauge shipping refers to cargo whose dimensions exceed standard container limits – height, width, or length – and therefore cannot fit in a standard container or trailer. It requires specialized containers such as flat racks and open tops, detailed securement plans, route permits for oversize trucking, and precise planning to ensure safe transit across road, rail, and sea.

Common Trucking-Related OOG Mistakes

1. You choose a trucker that doesn’t specialize in shipping OOG cargo

Only a minority of trucking companies transport oversize cargo. Others might tell you they can handle the load, but do they have the know-how and equipment needed to move your freight safely, legally and cost-efficiently? Do they understand permit requirements for oversize cargo? Do they know how to perform a route survey to avoid hazards such as low overpasses? A trucking company that doesn’t have solid experience with out of gauge cargo shipping could steer you toward all kinds of trouble – cargo damage, transportation delays or highway accidents that might land you in court.

2. You give your logistics provider insufficient information about your load

A large item’s specifications determine the equipment needed to transport it, and how it should be loaded and secured. Also, state permits for over-the-road transportation must include accurate numbers for the load’s dimensions and weight. If the permit says the load is 120” tall, but then the trucker finds that the height is really 130”, you will have to spend extra time and money redoing the permits.

If the trucker doesn’t catch the mistake, an inspector at a weigh station might and then put the truck out of service for hours, or even days, until the trucker gets new permits. Or else crews at the port might handle the load incorrectly because they don’t have the complete specs.

A separate height issue: the floor of a flat rack is about 1.5” feet thicker than a standard container in order to maintain structural integrity and allow for heavier payloads. For this reason, the container may have to be delivered on a specialized chassis, bringing the floor closer to the ground and providing more room for cargo height.

If you don’t give your transportation service provider accurate measurements, plus technical drawings or photographs, if possible, you’re making a big mistake.

3. You fail to account for weight distribution

According to a federal requirement called the Bridge Gross Weight Formula, the more an oversize load weighs, the longer the chassis you need, with more axles underneath. The aim is to distribute the weight of the load so it doesn’t exert a damaging amount of force on the highway. This also becomes complex as there are differing truck weight limits by state.

When the truck transporting your OOG freight pulls into a weigh station, even if the trucker’s permit shows the right dimensions and weight, if that weight isn’t distributed correctly over the axles, an inspector will pull it off the road.

Weight distribution is especially tricky when you ship factory equipment, construction machinery or other huge items that are shaped irregularly, with more weight concentrated in some parts than others.

Trucking OOG Cargo to the Port

You as a shipper can opt to have your logistics provider bring a flat rack or open top container to your location, in which case you are responsible for loading and proper securement. With standard types of trailers (dry van, flatbed, etc.), the driver, not the shipper, is the one responsible for proper securement. 

Here’s what’s involved:

Verify Dimensions and Weight: Measure overall height, width, and length plus center of gravity to confirm it fits within containerized limits for road, rail, and vessel stowage.

Stow on Dunnage: Place sturdy blocking under the cargo to clear the rack’s floorboards and distribute weight evenly.

Twist‑Lock Preparation: Ensure the rack’s corner castings are unobstructed so the drayage chassis and vessel gantry can lock it in place.

Securement Plan: Provide a lashing and dunnage diagram to your carrier or freight forwarder, certifying that each tie‑down point meets the vessel’s lashing requirements.

Documentation: Include an OOG packing list, detailed stowage instructions, and a signed cargo securing manual (CSM) certificate.

The other option is to have your logistics provider pick up the OOG cargo at your location using a trailer (flatbed, low boy or step deck), bring it to their warehouse and have it transloaded onto a flat rack or open top container for transit to the port of departure.

Freight forwarders that specialize in OOG shipments are very knowledgeable about every aspect of proper securement. This means there is less risk the load will fail inspection by the National Cargo Bureau (NCB), which is required for all OOG freight shipped on flat racks. 

While inspections are typically conducted at or near the port, your provider can arrange for an NCB at your location for an additional fee. The advantage here is quickly identifying any loading/securing issues that can be fixed at point of origin instead of at the port, where it can be 2x to 3x the cost.

“We have seen it happen where a shipper or their supplier loaded and secured the cargo themselves, only to find out that the container failed NCB inspection at the port,” said Andrew Rozek, president of New Jersey-based global forwarder, I.C.E. Transport. “This has always resulted in the cargo having to be reworked at the port and all related charges paid by our customer.”

Common Ocean Freight-Related OOG Mistakes

1. You let the load obstruct one or more corners of the container

When you use an open top, flat rack or platform container for out of gauge cargo shipping on the ocean, the cranes that lift the cargo on and off the vessel must attach to the corners of the conveyance. When your container arrives at the port, if the load blocks any of the corners (as in “twist lock preparation” above), the port will refuse it. Then you’ll have to get your trucker to transport your cargo to a nearby facility. If you’re very lucky, you’ll find a way to reconfigure the load to leave all four corners free. But more likely, you’ll have to arrange to unload the freight so the trucker can return the empty container to the port. Then you’ll need to rebook your cargo on a RO-RO (roll on-roll off) ship. All told, a time-consuming and costly exercise.

The lesson isn’t just that you need to be careful about how you load an oversize shipment. It's that you should consider the size and shape of oversize cargo before you make a booking. Some OOG cargo simply doesn’t fit on any kind of container. To avoid wasting money and time, think hard and early on about whether it’s best to use a flat rack or RO-RO.

2. You secure the load incorrectly

To prevent shifting in transit, shippers generally use straps, and often chains as well, to secure oversize cargo. They also use lumber to fill any empty space. How exactly to secure an OOG load depends on its weight, size and shape. It’s extremely important to get this process right, since shifting could damage the load or maybe pose a safety concern.

Improper blocking and bracing creates an extra risk when you ship oversize cargo on a flat rack container. Before port employees load a flat rack on a vessel, an inspector examines it to make sure it’s secured according to standards set by the National Cargo Bureau (NCB). If you fail the inspection, you’ll have to pay someone to rework the freight so it will pass. That creates an extra cost, and the delay could even make you miss your sailing.

3. You use the ocean container for last-mile transportation

If you transport your OOG load all the way to the final destination in an open top container, flat rack or platform, the trucker will charge you for returning the empty container to the port. Unless the final destination is very close to the port, it’s usually cheaper to transfer the cargo to a truck trailer for the final leg of the trip.

How much more do OOG shipments cost vs. standard freight?

The cost of OOG shipments is based on the specific dimensions and weight of each shipment. So, there's really no way to give a reliable percentage difference on how much more expensive it is. Rates will also vary from one carrier to another.

What should shippers look for in an OOG shipping partner?

First and foremost, look for a partner with proven experience shipping OOG cargo. Experience and attention to detail matter.  When it comes to OOG shipments, due to their very nature and because they are subject to many additional regulations, there is very little room for error. And errors more often than not result in significant additional expenses.

Due to the size and potential hazard of OOG cargo, there are very specific rules governing where, when and how it can be transported. The DOT as well as state and local authorities place tight restrictions on routes that can be taken, on what days, and at what time of day. If a mistake is made and a load is refused transit, time is lost and costs mount. That’s why having a knowledgeable partner with awareness of what is/isn’t allowed and what does/doesn’t work with OOG, is critical for shippers.

Press your potential shipping partners for details on their experience. It’s easy to say you ship OOG on a website or a sales sheet, so to distinguish the OOG shipping experts from the imposters make sure you ask them questions only a true expert could answer. 

I.C.E. Transport, a specialist with decades of experience in out of gauge cargo shipping, is one such expert.  Here are a couple of recent examples:

• Huge Tires Can’t Clear Overpass. A major manufacturer of huge, heavy-equipment tires was shipping from a factory in the Midwest to a warehouse in Texas, where it was to be transloaded into open top containers and trucked to the Port of Houston. The only thing was, the height of the load created a clearance issue at a bridge along the only route from the warehouse to the port. I.C.E. identified the problem and was able to successfully reroute to an alternate warehouse for transloading and shipment to the port, preventing a costly delay for the customer.
• Escort Required.  For another customer, I.C.E. arranged the complex logistics of an OOG shipment that, because of its length and width characteristics, had permitting that required not only a regular escort but a police escort along the highway.
  
  

How to avoid trouble when shipping  OOG freight

Shipping OOG cargo comes with extra risk. A seemingly minor slip-up could trigger oversized consequences – a huge machine sidelined at a weigh station, an urgent shipment turned away from the port, thousands of dollars in extra expenses, even a costly lawsuit.

Of course, you can also ship oversize cargo without those problems. Companies do it every day. The key is to understand the whole process, plan the transportation carefully and then execute that plan correctly.

If you don’t have the necessary expertise in house, consider teaming up with a freight forwarder like I.C.E. Transport that knows how to evaluate all the options and avoid the pitfalls that can lead to pricey mistakes.

For help with an upcoming OOG shipment, contact the experts at I.C.E. Transport.