Relative index for air, truck, and rail.
Transport impact index = kg × km × mode factor (air 1.13, truck 0.2, train 0.03)—relative score, not regulatory CO₂.
Impact score ≈ 320.0 (kg·km × factor)
Human-readable impact: moving the same 2 kg 800 km by truck instead of air would roughly change the score by a factor of 0.18×; rail is another 0.15× softer than truck—great for prioritizing which leg of the journey to shorten first.
Food Miles Tracker helps you relative index for air, truck, and rail. It is commonly used by engineers, lab users, field operators for food miles, freight emissions proxy, local food calculator.
Model
Impact = kg × km × factor with factors air 1.13, truck 0.2, train 0.03 (dimensionless education weights—not regulatory CO₂).