Powered axle lines
Axle lines belonging to the vehicle supplying power. Record the physical layout without assigning an operator class.
Field guide 03 · Observation
Why Axles and Vehicle Combinations Matter on Toll Roads
A field note can record which axle lines appear to contact the road. It cannot convert that observation into an official class, billed axle count, or toll amount.
Plain language
An axle line is not a wheel count
Dual tires, single tires, lifted assemblies, and trailer designs can make a visual walk-around less obvious than counting visible wheels.
Trailer axle lines
Road-contact axle lines beneath the attached trailer assembly, whether the trailer is empty or loaded.
Raised or lowered axles
Adjustable equipment creates operator-specific questions. Record position and verify current treatment instead of assuming.
Single vs. combination
The same powered vehicle can travel alone on one leg and as part of an attached combination on another.
Fixed comparison
Spot what changed
Toggle between two prepared drawings. The highlight identifies a physical change only.
Observed change: none attached in this fixed example.
Observed change: a coupling, rolling unit, and additional road-contact axle line appear.
Three examples
Observe the carrier, load, and road together
Wheel-lift tow
Part of a disabled vehicle is lifted while another axle line may continue to contact the road.
Flatbed transport
The carried vehicle’s wheels may all rest on the deck; describe them as cargo, separate from the carrier’s axle layout.
Boat trailer
The boat does not create road-contact axle lines by itself; the trailer assembly beneath it does.