Heavy Haul Glossary

The total weight carried by a single axle of a vehicle. Federal bridge formula and state regulations limit axle weights to prevent road damage, typically 20,000 lbs for a single axle and 34,000 lbs for a tandem axle.

A legal document issued by a carrier to a shipper that details the type, quantity, and destination of goods being transported. It serves as a receipt, contract, and document of title.

A specialized trailer designed for transporting wind turbine blades. These trailers feature adjustable rear steering dollies to navigate corners with blades up to 80+ meters long.

A mathematical formula used to determine the maximum weight allowed on any group of consecutive axles. The formula ensures that weight is distributed to prevent bridge damage: W = 500[(LN/(N-1)) + 12N + 36]

Insurance coverage that protects against loss or damage to freight while in transit. Heavy haul cargo insurance typically provides higher limits than standard trucking insurance.

A pilot car or escort vehicle that follows behind an oversize load to warn approaching traffic and assist with safe passage. Also called a rear escort or trail car.

Time-based restrictions on when oversize or overweight loads may travel. Many states prohibit wide loads during rush hours, weekends, or holidays. These vary significantly by state.

Operating a truck without cargo, typically when returning from a delivery. Deadhead miles add cost to transportation without generating revenue.

Federal and state agencies responsible for regulating transportation. The USDOT oversees interstate commerce while state DOTs handle intrastate regulations and permit issuance.

A trailer with two deck heights—a higher front and rear section with a lower middle "well" section. This design provides maximum height clearance for tall loads in the well area.

Short-distance transport, typically referring to moving cargo from ports to nearby warehouses or rail yards. Port drayage often involves heavy or oversized container cargo.

A vehicle that accompanies an oversize or overweight load to ensure safe passage. Escort vehicles warn other motorists, check clearances, and assist with traffic control. See also: Pilot Car.

A trailer with a flat, open deck without sides or roof. Flatbeds are commonly used for heavy equipment, steel, lumber, and other cargo that can be secured with chains and straps.

Federal Motor Carrier Safety Administration. The federal agency within DOT that regulates the trucking industry, issues operating authority, and enforces safety regulations.

The front portion of a trailer that connects to the tractor via a fifth wheel coupling. In RGN trailers, the gooseneck is removable to create a loading ramp.

The total weight of a vehicle including cargo, fuel, driver, and all equipment. Federal limits are typically 80,000 lbs for standard trucks on interstate highways.

Hazardous materials requiring special handling, documentation, and placarding during transport. Heavy haul may involve hazmat when transporting industrial equipment with residual chemicals.

Transportation of oversize and/or overweight cargo that exceeds standard legal limits. Heavy haul typically involves specialized equipment, permits, and escort services.

A measuring device extending from an escort vehicle to verify overhead clearances for tall loads. The height pole operator confirms clearance under bridges, power lines, and other obstacles.

An escort vehicle equipped with an adjustable pole to measure overhead clearances. High pole operators verify that the route is safe for loads exceeding 14 feet in height.

A trailer suspension system using hydraulic cylinders to adjust deck height and distribute weight. Essential for loading operations and navigating uneven terrain.

Transportation involving multiple modes (truck, rail, ship). Heavy haul often involves intermodal logistics when moving cargo from ports to final destinations.

An auxiliary axle unit added to the front of a trailer to distribute weight over more axles. Jeeps allow heavier loads while maintaining legal axle weights. Also called a converter dolly.

A pilot car that travels ahead of an oversize load to warn oncoming traffic and verify clearances. Lead escorts are required for wide and tall loads in most states.

A load that meets all standard dimension and weight limits without requiring special permits. Typical legal limits: 8'6" wide, 13'6" tall, 53' long, 80,000 lbs gross.

A trailer with an extremely low deck height (18-24 inches) designed for tall equipment. Lowboys maximize vertical clearance but typically require crane loading.

Motor Carrier number issued by FMCSA authorizing interstate transport of freight. Required for companies operating commercial vehicles across state lines.

A trailer with multiple axle lines (9, 13, 19, or more) to distribute heavy loads. More axles allow heavier cargo while meeting bridge formula requirements.

Oversize/Overweight. The common abbreviation for loads exceeding legal dimensions or weight limits, requiring special permits for transport.

A load that exceeds legal dimensional limits in width, height, or length. Oversize loads require permits and may need escort vehicles.

A load exceeding legal weight limits (gross weight, axle weight, or bridge formula). Overweight permits specify routing and may restrict certain bridges.

Authorization from a state DOT to transport loads exceeding legal limits. Permits specify allowed routes, times, required escorts, and other conditions.

A vehicle that escorts oversize loads to ensure safe transport. Pilot cars warn traffic, check clearances, assist with traffic control, and communicate with the driver.

A trailer type where the front section (gooseneck) detaches, allowing the trailer to rest on the ground as a ramp. This enables self-propelled equipment to drive on.

Physical inspection of a planned transport route to verify clearances, bridge capacities, road conditions, and potential obstacles before moving an oversize load.

A specialized trailer where the cargo becomes part of the trailer structure. The load is suspended between two trailer sections, maximizing weight distribution for extreme loads.

A permit valid for one specific oversize/overweight move. Single trip permits specify the load dimensions, route, and time validity (typically 5-14 days).

A platform vehicle with many independently steerable axles and computer-controlled hydraulic systems. SPMTs transport extremely heavy loads (millions of pounds).

An operator who controls the rear axles of a long trailer to navigate turns. Steermen use remote controls or ride on the trailer to steer rear dollies.

A trailer with two deck levels—a higher front deck and a lower rear deck. The step down provides additional height capacity compared to a standard flatbed.

An auxiliary axle unit added behind a trailer to distribute weight. Similar to a jeep but positioned at the rear of the load.

An extremely large or heavy load exceeding typical oversize permit thresholds. Superloads require extensive planning, bridge analysis, and special authorization.

Covering cargo with waterproof tarps to protect against weather. Tarping requirements vary by cargo type; some loads cannot be tarped due to dimensions.

A trailer where the deck tilts to create a loading ramp. Tilt decks allow equipment to drive on without a removable gooseneck.

A configuration with three axles in a group. Tri-axle trailers distribute weight more effectively than tandem (two-axle) configurations.

Transportation Worker Identification Credential. A biometric card required for workers accessing secure port areas. Heavy haul drivers picking up from ports need TWIC cards.

A load exceeding the standard legal width of 8'6". Wide loads require permits and typically need pilot car escorts. Widths over 14-16' may require traffic control.

A mechanical device used to pull equipment onto trailers. Trailer-mounted winches assist in loading non-running equipment or positioning heavy items.