Tonnikilometri

Tonnikilometri, or tonne-kilometres (symbol: tkm), is a unit used to quantify freight transport activity. It measures the amount of work involved in moving goods by combining mass and distance. One tonnikilometri represents the transport of one metric tonne (1000 kilograms) over one kilometre.

Calculation and usage: tkm is calculated by multiplying mass in tonnes by distance in kilometres (tkm = tonnes × kilometres). The unit is additive, so the total tkm for a shipment or a fleet is the sum of the tkm for all movements. This makes it useful for comparing overall transport activity, measuring changes over time, and benchmarking efficiency across modes, routes, or policies. It is commonly used in transport statistics to relate activity to energy use or emissions.

Applications: Tonnekilometri is used in logistics and policy analysis to express freight movement independent of vehicle type. Analysts relate energy consumption and greenhouse gas emissions to tonne-kilometres, yielding metrics such as energy per tkm or emissions per tkm. The measure supports assessments of modal shifts, infrastructure investments, and efficiency improvements.

Relation to other units: The concept is equivalent to the ton-mile used in some English-language contexts, with the main difference being metric units (tonnes and kilometres) versus imperial units (tons and miles). In Finnish and other Nordic contexts, tonnikilometri is the standard term, often abbreviated as tkm.

In summary, tonnikilometri provides a simple, standardized way to quantify freight transport activity by combining the amount of goods moved with the distance they travel, facilitating comparisons and policy analysis in logistics and transportation.