Heavy Haul Glossary
50+ industry terms defined. The most comprehensive heavy haul and oversize load terminology reference.
A
Amber Light
Flashing yellow/amber warning lights mounted on pilot cars and escort vehicles as required by most jurisdictions.
Axle Weight
The total weight bearing on a single axle of a vehicle, subject to legal limits per axle configuration.
Annual Permit
A permit valid for one year, allowing multiple trips within specified dimension and weight limits.
Abnormal Load
UK/EU terminology for a load that exceeds standard dimensions or weight limits.
B
Bridge Formula
Federal formula that determines the maximum weight any set of axles can carry based on the number and spacing of axles.
Beam Trailer
An extendable trailer designed for extremely long loads like bridge beams, wind turbine blades, and industrial columns.
Bucket Truck
A utility vehicle with an elevated bucket used to lift power lines for oversize load passage.
Bondable
An operator who can obtain a surety bond, demonstrating financial responsibility and trustworthiness.
Bobtail
Operating a truck tractor without a trailer attached.
C
Corridor
A frequently used transport route between two cities or regions, often with established escort operator coverage.
Curfew
Time restrictions on oversize load movement, typically prohibiting travel during rush hours, nighttime, or holidays.
Cargo Insurance
Insurance covering damage to freight during transport, separate from vehicle liability insurance.
D
Dead Head
Driving without a load, typically returning from a delivery. A significant cost factor in heavy haul operations.
DOT Number
A unique identifier assigned by the FMCSA to commercial motor carriers for identification and safety monitoring.
Dual Lane
When an oversize load occupies two lanes of traffic, requiring additional escort vehicles and traffic control.
E
Escort Vehicle
A vehicle accompanying an oversize or overweight load to provide safety and traffic control.
ELD
Electronic Logging Device — a device that automatically records a driver's driving time and Hours of Service (HOS) compliance.
F
FMCSA
Federal Motor Carrier Safety Administration — the US agency that regulates the trucking industry.
Flatbed
An open trailer with a flat deck and no sides, used for hauling construction materials, steel, and equipment.
Flag Car
Another term for pilot car/escort vehicle, particularly common in Australian heavy haul terminology.
Fifth Wheel
The coupling device on a tractor that connects to the trailer kingpin, allowing articulation.
G
Gross Vehicle Weight (GVW)
The total weight of a vehicle including the load, fuel, passengers, and equipment.
H
Height Pole
A pole mounted on a pilot car set to the height of the load behind it, used to check clearances under bridges and power lines.
HOS
Hours of Service — federal regulations limiting how long a commercial driver can operate a vehicle before required rest.
High Pole
The practice of measuring heights along a route using a height pole to ensure clearance for tall loads.
I
IFTA
International Fuel Tax Agreement — a system for collecting and distributing fuel taxes among US states and Canadian provinces.
K
Kingpin
The coupling pin on a trailer that connects to the fifth wheel on a truck tractor.
L
Lowboy
A semi-trailer with a very low deck height, used for hauling tall equipment like excavators and bulldozers.
LEA Escort
Law Enforcement Agency escort — a police officer who accompanies an oversize load, often required for superloads.
M
MC Number
Motor Carrier number — operating authority granted by FMCSA for interstate commerce.
Multi-State Permit
A permit covering transport across multiple states, sometimes available through regional agreements.
N
NHVR
National Heavy Vehicle Regulator — the Australian agency responsible for regulating heavy vehicles.
O
Oversize Load
A load that exceeds standard legal width, height, length, or weight limits, requiring a special permit.
Overweight Load
A load that exceeds the standard gross vehicle weight limit on public roadways.
P
Pilot Car
A vehicle that leads or follows an oversize load to warn other motorists and guide the transport through obstacles.
Permit
Government authorization to transport an oversize or overweight load on public roads, specifying route, dimensions, and conditions.
Perimeter Trailer
A heavy-haul trailer that carries weight around the perimeter rather than on the deck surface.
R
Route Survey
A pre-trip inspection of the planned transport route to identify obstacles, low clearances, tight turns, and road conditions.
RGN (Removable Gooseneck)
A trailer where the gooseneck detaches for ground-level loading of heavy equipment.
S
Superload
A load that exceeds standard oversize permit limits, requiring special routing, engineering studies, and multiple escorts.
Single Trip Permit
A permit valid for one specific trip, specifying exact origin, destination, route, and time frame.
Step Deck
A trailer with an upper and lower deck, allowing taller cargo while maintaining overall height compliance.
Schnabel
A specialized trailer that connects to the load itself, making the load part of the trailer structure. Used for transformers and heavy industrial equipment.
STGO
Special Types General Order — UK regulation governing the movement of abnormal loads on public roads.
T
Tandem
A pair of axles close together, distributing weight more evenly across the road surface.
Tri-Axle
A trailer or truck with three axles, allowing it to carry heavier loads while distributing weight.
U
Utility Clearance
The process of coordinating with utility companies to temporarily raise or de-energize power lines along a transport route.
W
Wide Load
A load exceeding the standard width limit (typically 8'6" in the US), requiring oversize permits and often escort vehicles.
Wind Speed Restriction
Maximum wind speed at which an oversize load can safely travel, particularly relevant for tall or wide loads.