personkilometres

Person-kilometre, abbreviated pkm, is a unit of travel demand equal to the amount of travel performed by one person in one kilometre. It is defined as the product of the number of passengers and the distance they travel, summed across all trips.

Calculation: pkm = sum over trips (passengers × distance in km). Examples: 3 people traveling 5 km yields 15 pkm. A bus with 40 passengers traveling 8 km yields 320 pkm.

Uses: pkm is used in transport planning to express total passenger travel independent of vehicle or mode; it is also used to assess energy use and emissions per pkm and to compare modes in terms of travel demand and efficiency.

Relation to other measures: pkm relates to vehicle-kilometres (vkm) by pkm = vkm × average occupancy; occupancy can be calculated as pkm / vkm. This helps analysts separate distance traveled from occupancy effects.

Limitations: pkm does not capture travel time, variability in occupancy over a trip, or differences between long and short trips beyond distance; it does not reflect vehicle type, weight, or in-vehicle conditions.

In statistics: pkm is widely used by international organizations and national agencies to quantify passenger travel, monitor modal shifts, and support transportation and environmental analyses. See also vehicle-kilometre, tonne-kilometre, and passenger-kilometre for related metrics.