How to Block & Brace Intermodal Freight Shipments

Blocking and bracing is the practice of securing freight inside an intermodal container so it cannot shift in transit due to harmonic vibration, handling shock, and containers that can ride in either direction. Done correctly, it prevents damage, keeps a load legal on weight, and costs far less than reworking a shipment that moved.

There is nothing more important to a shipper than freight that arrives on time, on budget, and undamaged. That last word, undamaged, is where blocking and bracing earns its place. It is a practice vital to a successful intermodal load, and also simpler than many shippers believe once they know where to look and who to ask.

Over-the-road truckload freight has to be blocked and braced to limit cargo movement inside the trailer. Intermodal asks for more, because the rail segment introduces forces the road does not. Understanding those forces is the first step, and everything else follows from it.

Key Takeaways:

- Blocking and bracing prevents cargo movement caused by rail harmonic vibration
- Most effective methods are simple: stretch wrap + 2x4s with 16d nails
- Work with your IMC to develop a load plan approved by the railroad
- Proper blocking and bracing is legally required and reduces damage costs
- Cost is minimal compared to savings from using intermodal vs. truckload

What's Changed (July 2026 Update):

We first wrote this piece in 2020, but have since updated blocking and bracing guidance to reflect current railroad standards 
and best practices. Added references to latest CSX and Union Pacific guidelines and a recent Intermodal Logistics Podcast episode on the subject with MxV Rail expert Kelsey Even.

Why intermodal is different from truckload

Freight on a truck experiences a fairly predictable pattern of movement. The driver accelerates, brakes, corners, and occasionally backs up, so most of the load's energy pushes toward the nose of the trailer. A shipper who has loaded trucks for years has an instinct for that pattern.

Rail changes the pattern in three ways.

The first is vibration. Steel wheels on steel rail produce a steady, consistent vibration across the entire journey, sometimes described as harmonic vibration. It is not the jarring of a truck on a rough road. It is gentle and continuous, and that is exactly what makes it deceptive. Some freight responds well to it. Other freight, depending on its packaging and how it resonates, gets an extra shake that works fasteners loose and walks a load out of position over hundreds of miles. (For a deeper look at this single force, see our piece on the harmonic vibration impact on intermodal freight shipments.)

The second is shock from handling. A container is lifted on and off rail equipment, and often on and off a vessel, by crane. It is coupled and moved in the rail yard. Each of those handling events sends a shock through the load that a truck shipment never sees.

The third is direction. A truck load knows which way it is going. An intermodal container can ride backward for the entire rail segment, or forward, and the shipper does not control which. That means a load braced only toward the doors is braced for half the trip. Freight has to be secured for movement in every direction, not the one a driver would expect.

Put those three together and the reason for the extra care becomes clear. The mode is not more dangerous. It simply moves freight through a wider set of forces, and the securement has to account for all of them.

What "AAR approved" actually means

Shippers often ask whether a given securement method is approved or tested by the Association of American Railroads. The precise answer is useful, because it tells you where to find the right method rather than guessing at one.

A securement method is documented in the industry's loading guides after it has been tested to a common standard. Two reference documents carry that work. The first is Circular 43, the rules governing the loading of containers and trailers for intermodal service. The second is the Intermodal Loading Guide, which holds the tested load patterns and securement methods themselves. When a method appears in those guides, it has been evaluated the same way, to the same level, as every other method in them, which is what lets carriers across an interchange know what to expect.

The testing behind those guides is real, physical work. It runs through MxV Rail, the research, testing, and training organization that operates as a wholly owned subsidiary of the AAR out of Pueblo, Colorado, and works on behalf of North America's freight railroads as a group rather than for any single carrier. A method typically starts with impact testing: a container or trailer is loaded with the actual commodity to its real shipping weight, the securement is applied the way it would be in service, and the unit is put through switching events that create the shock a load will meet in the yard. On-track and field testing follow, and a field trial has to travel a real distance (more than 500 miles), get checked at both origin and destination, and be monitored across a set of shipments before a method is reviewed and documented.

The practical takeaway for a shipper is simple. You do not have to invent a solution. For most freight, a tested pattern already exists, and the people who maintain those patterns want to help you find the right one.

Packaging is the foundation of load securement

Securement holds freight in position, but it can't rescue packaging that wasn't built for the trip. That distinction matters more than almost anything else on this page.

The work starts at the unit level, well before the container. Is the commodity packaged to survive a transportation environment, not just a static warehouse where it gets stacked and driven around on a forklift? A case, a bottle, or a can that is not strong enough on its own will not be saved by a perfectly secured load. The freight may arrive exactly where it was placed and still be damaged, because the packaging failed under the vibration.

There is a second, less obvious point. Securement can be strong enough to work against weak packaging. When straps or airbags press on a package that cannot take the force, the fix is often added protection, such as corner boards, so the securement holds the freight without crushing it.

Shippers moving from truck to rail sometimes need to revisit the pallet build for this reason. Case goods with significant overhang or underhang on the pallet may travel fine over the road and become a problem on rail, where the two-directional movement finds the weakness. The change can be as small as rotating the cases for a squared-off pallet. It is worth looking at before the first load, not after the first claim.

Weight distribution can fail a load that is fully braced

Weight is its own discipline in intermodal, and a load can be braced correctly and still fail if the weight is in the wrong place.

The balance has to work for every leg of the trip. Axle weights govern the over-the-road portion. Rail adds an overhead or crane lift. Ocean adds its own requirements. Freight loaded too far forward or too far back can pass at one point and cause a problem at another. A well-known example: when an intermodal ramp goes to pick up a container and senses a weight imbalance in the lift, the equipment is set back down. The load does not move until the balance is corrected, even though it may be perfectly secured.

There is also a failure mode that surprises shippers. A load that is legal on weight at origin can shift in transit, and a shifted load can become overweight or go out of balance somewhere along the route. At that point the shipper owns the cost and the delay of reworking it. That is a securement failure showing up as a weight problem, which is why the two subjects belong together. Our guide to intermodal weight covers the balance question in full.

What the freight actually does inside the box

One principle explains most damage, and it is worth stating plainly: freight seeks stability, and it will move until it contacts something, regardless of weight.

That single idea corrects several common assumptions. Heavy freight is not exempt. Weight does not hold a load in place; a heavy commodity still wants to move and find a wall to rest against. An unfilled gap, even six to twelve inches, is an invitation for the load to travel until it closes that gap on its own, usually with force. And bracing toward the doors alone leaves the freight free to move toward the nose, which is exactly where a backward-riding container sends it.

The counterintuitive move that follows: if the freight is going to end up against the wall, start it against the wall. A load placed at the wall from the beginning has a better chance of surviving than one that starts in open space and slams into the wall in transit. Fill the voids, brace in both directions, and let the container's own structure do part of the work.

Blocking and bracing methods have come a long way

Blocking and bracing used to mean lumber and nails. Historical loading documents are full of wood bracing and nailing patterns, and for certain commodities wood is still the right answer. But it is no longer the only tool, and for many loads it is no longer the best one.

Airbags, strapping systems, and adhesive methods now cover a wide range of freight. They are frequently faster to apply than building a wood structure, and they are far easier on the receiver at the other end. That second benefit is easy to overlook. A wood-and-nail brace has to be dismantled and disposed of at destination, which costs the receiver time and creates waste. A strap or an airbag comes out quickly and leaves little behind. As securement has evolved, the whole journey has gotten cleaner, not just the loading dock.

The right method also depends on the container. Bracing that works in a 53-foot box is not automatically right for a 40-foot or a 20-foot container. On a shorter box a shipper may load closer to the door than on a 53, and the weight balance has to be reconsidered when a pattern is adapted from one size to another. A good loading guide notes the size a pattern was tested in for exactly this reason.

The cost math most shippers get wrong

The most common objection to proper securement is that it adds cost and time. Looked at across the whole life of a shipment, the opposite is true.

Damage is only the tip of the pyramid. Below the visible cost of the damaged freight sits a stack of other costs: producing replacement freight, shipping it again, recovering or reworking the original, disposing of what cannot be salvaged, and sometimes remediating a site where a load failed. Set the cost of a few airbags or straps against that stack and the securement is a rounding error. Skipping it does not save money. It defers a much larger bill to destination.

The time concern deserves a fair look too. Yes, securing a load takes longer than closing the doors on a stack of pallets. But a load that arrives intact saves the receiver from hand-stacking, from puzzling out a damaged unload, and from filing a claim. And the up-front time drops quickly. Crews new to a method may take longer on the first loads while they learn the buckles and the sequence, then average application time falls as they find the rhythm. Within a couple of weeks it becomes routine.

The blocking and bracing mistake to watch for, and the fix

When damage does happen, the cause is usually not exotic. The most common problem the rail carriers report is simply not enough securement: one airbag where the load needed two or three, one strap where it needed four or five, or close to none at all.

The fix is a back-to-basics check that any operation can run:

• Is the load tight, with the voids filled?
• Is the packaging strong enough for the transportation environment, not just the warehouse?
• Is there overhang or underhang on the pallets that should be squared up?
• Are the straps fully tensioned?
• Are the airbags inflated to the correct pressure, not just to the first pop?

Standards drift over time, especially if a securement vendor has not walked the floor in a while and habits have quietly loosened. A periodic review against these fundamentals catches most of it.

Where a shipper starts, and who owns it

One structural point often surprises shippers new to the mode. In truckload, the driver, and by extension the carrier, is generally responsible for a properly secured load, because the load stays with that driver the whole way. In intermodal, the container is sealed and moves across modes and carriers, so the shipper takes responsibility for blocking and bracing the load before it leaves the dock. A damage claim on an intermodal load will not be paid without proper bracing present, and the costs of a shifted, out-of-balance load fall to the shipper.

That responsibility sounds heavier than it is in practice, because the shipper does not carry it alone. A good intermodal provider makes the connections. As an IMC, we orchestrate the full door-to-door move, and part of that job is getting the right loading diagram in a shipper's hands and pulling in the people who know the freight best.

The resources are deep, and most of them are free:

• Your intermodal partner or IMC knows which railroads will handle the freight and can bring their teams in.
• The Class I railroads and many short lines maintain dedicated shipment-quality, load-securement, or damage-prevention groups. They want to talk to shippers, especially about an unusual commodity they have not seen before.
• Dunnage vendors carry real expertise across modes. If you already use one for airbags or strapping, tell them you are moving to rail so they can switch you to rail-tested equipment. If you do not tell them, they cannot.
• MxV Rail publishes loading patterns, the reference guides, and contact information at no cost, and maintains the tested patterns most standard freight can use straight out of the guide.

For a deeper look at how a securement method gets tested and what to ask before the first load, our podcast conversation with Kelsey Even of MxV Rail, from the Damage Prevention and Load Services group, walks through the whole process.

The timeline is shorter than most fear. Standard palletized freight rarely needs much beyond good void fill and a squared load. The longer conversations are for the unusual commodities, and the shippers moving those usually know they have an unusual commodity already. The one piece of advice worth repeating: give it a little lead time. A few weeks lets the right supplies arrive and the right people weigh in, rather than solving it at the dock with the clock running.

Things to remember about blocking and bracing

Blocking and bracing is not the obstacle to intermodal that many shippers assume. It is a known, well-supported part of moving freight on rail, and the effort it takes is small against the cost of getting it wrong.

• Prepare for every leg, not the last one. Vibration, handling shock, and a container that can ride either direction all shape how a load has to be secured.
• Start at the package, not the strap. Securement holds freight in place; it cannot fix packaging that was not built for the trip.
• Fill the voids and start at the wall. Freight moves until it touches something, whatever it weighs.
• Use the people who already know the answer. The railroads' quality teams, the dunnage vendors, and the tested loading guides exist to solve this, usually for free.
• Give it lead time. The first load takes the longest; after that it is routine.

The shippers who treat securement as part of the plan, rather than a step to rush at the dock, are the ones who stop seeing damage claims and start seeing intermodal as the reliable option it is built to be.

Frequently Asked Questions

What is blocking and bracing in intermodal shipping? Blocking and bracing is the practice of securing freight inside an intermodal container so it cannot shift during transit. It uses materials such as airbags, strapping, adhesive methods, or wood bracing to hold the load in position against the vibration and handling forces of a rail move.

Why does intermodal need more blocking and bracing than truckload? Rail adds forces a truck does not: steady harmonic vibration from steel wheels on steel rail, shock from crane and yard handling, and containers that can ride forward or backward for the entire rail segment. Securement has to account for movement in all directions, not just toward the nose of a trailer.

Who is responsible for blocking and bracing an intermodal load? The shipper is. Because an intermodal container is sealed and moves across multiple carriers and modes, the shipper is responsible for securing the load before it leaves the dock. A damage claim will generally not be paid without proper bracing in place.

What happens if a load is not braced correctly? The freight can shift, which risks product damage and can throw the container out of balance or over legal weight in transit. A shifted, out-of-balance load has to be reworked, and those costs and delays fall to the shipper.

Does proper blocking and bracing cost a lot of extra time and money? No. The materials are a small cost against the full price of damage, which includes replacement freight, reshipping, rework, and disposal. Application takes longer at first, then becomes routine within a couple of weeks as crews learn the method.

Where can I get help securing an intermodal load? Start with your intermodal provider or IMC, who can connect you to the railroads' shipment-quality teams. Dunnage vendors and MxV Rail's published loading guides are additional resources, most of them free.

Related Reading

• Harmonic Vibration Impact on Intermodal Freight Shipments
• Intermodal Weight, the Most Common Issue for Shippers
• Shipping Steel Via Intermodal
• When Intermodal Is the Wrong Choice, and What to Use Instead
• The Complete Guide to Intermodal Transportation

If you would like to evaluate how intermodal fits your freight, including a look at what your lanes and commodities need for a clean, damage-free move, visit the InTek Logistics blog. For a lane-by-lane evaluation, we are here to help.

If you are looking for more of a visual in the blocking and bracing process, we recommend the following videos from the Union Pacific and CSX.

Union Pacific Intermodal Guidelines 1.30 minute video

CSX blocking and bracing page and video 3.30 minute video

Quite often InTek directs its customers to LOGISTICK for cost effective blocking and bracing materials. The site has great pictures and videos for shippers interested in further understanding their blocking and bracing needs.