Vehicle Classification System – USA (FHWA Standard)

The Federal Highway Administration (FHWA) has established a 13-class system to categorize vehicles based on axle count, tires, and configuration. This classification is essential for traffic data collection, roadway design, and transport policy planning across the United States.

1. Motorcycles

Two- or three-wheeled motorized vehicles with saddle-type seats and handlebar steering.
Examples:

• Motorcycles

• Mopeds

• Motor scooters

• Motor-powered bicycles

• Three-wheel motorcycles

2. Passenger Cars

Vehicles designed primarily for carrying passengers.
Examples:

• Sedans

• Coupes

• Hatchbacks

• Station wagons

• Cars towing light trailers or campers

3. Other 2-Axle, 4-Tire Single-Unit Vehicles

Vehicles with two axles and four tires, excluding passenger cars.
Examples:

• Pickup trucks

• Vans

• SUVs

• Campers and motorhomes

• Ambulances, hearses, and minibuses

4. Buses

Vehicles designed for transporting passengers, typically with 2 axles/6 tires or 3+ axles.
Includes:

• Public transit buses

• School buses

• Intercity and shuttle buses

Note: Modified buses used as trucks should be classified under truck categories.

Truck Classifications

5. Two-Axle, Six-Tire Single-Unit Trucks

Vehicles on a single frame with two axles and dual rear wheels.
Includes:

• Medium-duty delivery trucks

• Motorhomes with dual rear wheels

6. Three-Axle Single-Unit Trucks

Single-unit vehicles with three axles.
Includes:

• Construction trucks

• Heavy-duty service vehicles

7. Four or More Axle Single-Unit Trucks

Single-frame vehicles with four or more axles.
Common in:

• Specialized industrial applications

8. Four or Fewer Axle Single-Trailer Trucks

Combination vehicles with a power unit and one trailer, totaling four or fewer axles.
Typically includes:

• Light-duty trailer combinations

9. Five-Axle Single-Trailer Trucks

One of the most common truck types on highways.
Examples:

• Standard 18-wheelers (tractor with one trailer)

10. Six or More Axle Single-Trailer Trucks

Combination vehicles with six or more axles, built for heavy hauling.
Includes:

• Long-haul freight carriers

• Construction transport

Multi-Trailer Truck Classes

11. Five or Fewer Axle Multi-Trailer Trucks

Vehicles with multiple trailers and a total of five or fewer axles.
Use Case:

• Specialized short-haul or regional transport

12. Six-Axle Multi-Trailer Trucks

Three or more units with six axles.
Examples:

• Long combination vehicles (LCVs)

13. Seven or More Axle Multi-Trailer Trucks

Heavy-duty, high-capacity transport configurations.
Use Case:

• Cross-country freight

• Oversized cargo transport