The following examples illustrate how some of the largest documented highway shipments in the United States pushed the limits of heavy haul transportation while demonstrating the planning required to move them successfully.

A Record-Setting Reactor Vessel Crossed Nevada

In June 2020, one of the heaviest loads ever permitted on Nevada highways began a 345-mile journey from North Las Vegas to a disposal facility in Clive, Utah. The shipment carried a decommissioned reactor pressure vessel from the San Onofre Nuclear Generating Station.

Including the transport equipment, the move weighed approximately 2.4 million pounds while carrying a 770-ton reactor pressure vessel. Six heavy-duty Class 8 tractors, with four pushing and two pulling, moved the load using a custom Goldhofer trailer that measured more than 300 feet in overall length and distributed the weight across hundreds of tires.

The convoy traveled at speeds of approximately 5 to 10 miles per hour after more than a year of planning involving transportation officials in California, Nevada, and Utah. Nevada officials described it as the heaviest load ever permitted to travel on the state’s highways.

A Giant Transformer Required 25 Trailer Axles in Arizona

A transformer weighing approximately 1,040,500 pounds, or about 520 tons, made its way across Arizona in 2014 after arriving from New Mexico on its way to Yuma.

The shipment measured roughly 305 feet long, 20 feet wide, and nearly 17 feet tall. To distribute its weight safely, the transporter used 25 trailer axles while traveling primarily at night under escort from the Arizona Department of Public Safety.

Route planning became just as important as the equipment itself. During one section of the trip, the convoy temporarily traveled westbound using the eastbound lanes of Interstate 10 because the transformer occupied too much roadway for normal traffic patterns.

Refinery Equipment Continues to Push Heavy Haul Limits

Refineries and petrochemical facilities regularly require some of the largest highway shipments in North America because many processing vessels, reactors, and coke drums cannot be manufactured at the job site.

These components often weigh well over one million pounds and require specially designed transport systems capable of distributing enormous weight across dozens of axle lines. Before permits are approved, transportation agencies evaluate bridges, pavement strength, turning movements, and overhead clearances, while utility companies may temporarily raise power lines or relocate roadside infrastructure to allow the shipment to pass safely.

The Federal Highway Administration notes that these superheavy moves play an important role in supporting industries such as oil production, chemical manufacturing, power generation, and national defense.

Size Creates Challenges Beyond Weight

Some of the most difficult shipments are not the heaviest. Wind turbine blades, for example, can exceed 250 feet in length, creating challenges that have little to do with weight and everything to do with maneuverability.

Specialized trailers equipped with steerable rear axles allow operators to guide blades through tight intersections, highway interchanges, and mountain roads that conventional trailers could never negotiate. Similar planning is required when transporting long bridge beams, precast concrete sections, and structural steel components that must arrive as single pieces for installation.

Every Superload Is Planned Long Before It Moves

Engineering begins long before the truck leaves the yard. Route surveys, bridge analyses, pavement evaluations, permit reviews, and utility coordination are completed before transportation agencies authorize a move.

Depending on the shipment, utility crews may temporarily lift overhead power lines, traffic signals can be removed and reinstalled, and intersections may be modified to create enough room for the convoy. While the truck is the most visible part of the operation, every successful superload depends on months of planning by carriers, engineers, permitting agencies, law enforcement, and utility companies working together.

Frequently Asked Questions

Who approves superload movements?

Superload permits are typically issued by state transportation agencies, although the approval process often involves engineers, utility companies, local governments, and law enforcement depending on the route.

Can one permit cover multiple states?

No. Superloads traveling across state lines generally require separate permits and approvals for each state because permitting requirements, escort rules, and travel restrictions vary by jurisdiction.

How long can it take to plan a superload?

Planning timelines vary depending on the size and complexity of the shipment. Some moves can be organized in weeks, while record-setting transports may require many months of engineering studies, route surveys, and agency coordination before receiving final approval.

Are the largest superloads always the heaviest?

Not necessarily. Some shipments create greater transportation challenges because of their length, width, or height rather than their overall weight. Long cargo such as wind turbine blades can require just as much route planning as extremely heavy industrial equipment.

The TDUSA editorial team creates practical, driver-focused content covering trucking news, industry updates, safety, regulations, and career information for professional truck drivers across the United States. Each article is built to reflect real-world experience, industry developments, and information drivers can use on and off the road.

Last Updated: July 20, 2026

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According to ODOT, the superloads contain no hazardous materials, fuels, or liquids. The shipments will travel at speeds of 10 to 30 miles per hour along designated routes, including U.S. 730, OR 37, Interstate 84 in Pendleton, U.S. 395, U.S. 26, and OR 201, before exiting Oregon into Idaho via OR 201 near Adrian. Oversized loads will operate from the Port of Morrow through Pilot Rock during nighttime hours and from Pilot Rock to the Idaho border during both daytime and nighttime hours. When not in transit, the loads will park off the main roadway.

Due to the extreme size of each shipment, both travel lanes on two-lane highways will be used, causing traffic delays. Vehicles will experience periodic stops, and pilot cars will escort the shipments, guiding them along the route. Designated pull-over sites will allow superloads to stop and give waiting vehicles a chance to pass.

ODOT urges all drivers to stay vigilant when encountering pilot vehicles escorting these oversized or overweight loads, as safety remains a top priority. Special permits and traffic management plans have been established to reduce risk for all road users along the transport routes.

What is a Superload?

A superload is a unique classification of oversized loads in Oregon. The term applies to shipments exceeding the following dimensions:

• Width: Over 16 feet on Interstates or over 14 feet on two-lane state highways (excluding certain mobile units with widths including up to a 12-inch eave).
• Height: Over 17 feet on any highway.
• Length: Greater than 150 feet overall.
• Mobile Units: Those with a width exceeding 14 feet for the box or a total width greater than 15 feet.

If you have inquiries regarding these heavy transports, Doug Smith of Omega Morgan can assist at 503-647-7474.

Motorists are encouraged to plan for these transports and allow extra travel time when driving along affected routes.

Source: Truckers News

The post Oregon DOT Announces Summer-Wide Series of ‘Superloads’ appeared first on Truck Drivers USA.

Coordinating Oversized Loads with ADOT

ADOT’s permitting process is central to managing oversized loads that include everything from wind turbine blades to houseboats. “This was definitely one of the more unusual loads we’ve permitted in recent years,” said Christina Pippin, ADOT permits technician. She noted that ADOT ensures public safety and minimizes wear on highways and local roads during such transports.

Preparing the Philippine Mars for Transit

The Philippine Mars seaplane’s size presented incredible logistical challenges. Standing 26.5 feet tall, measuring over 137 feet in length, and spanning 15 feet in width, the fuselage was one of the largest components to be transported. While its wings and engines were shipped separately as oversized loads, the fuselage required a specialized Class C permit issued by ADOT.

To minimize disruption, the transport primarily occurred at night, navigating major routes like Bell Road and State Route 85. The operation involved law enforcement escorts and utility crews to temporarily move overhead lines and adjust traffic control devices along the route.

Journey to Completion

After six carefully planned nights of travel, the Philippine Mars fuselage reached its destination at the Pima Air and Space Museum on Saturday, May 17. Meticulous coordination ensured a smooth process, keeping ADOT and local stakeholders, such as cities and counties, informed as plans were adjusted.

Courtney Mower, ADOT’s statewide permit services manager, explained the agency’s role in such operations. “Though our permit technicians are not physically on the road with these heavy loads, their expertise is fundamental to ensuring these shipments reach their destinations efficiently and safely,” said Mower. She also noted that ADOT processed over 6,500 oversized load permit applications in 2024, showcasing the agency’s extensive experience and capacity to handle unique transports.

Supporting Infrastructure and Oversized Shipments

While moving the Philippine Mars was a unique project, the steps taken emphasized ADOT’s dedication to supporting critical shipments while safeguarding infrastructure. This successful collaboration between private carriers, local governments, and ADOT underscores the importance of meticulous planning in managing oversized loads.

For more information about oversized permits and other ADOT services, visit azdot.gov/permits. Additionally, ADOT’s podcast highlights the valuable work of their oversized permit team.

Source: The Trucker
Image Source: ADOT

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