passengerkilometre

Passenger-kilometre (PKM) is a unit of measurement representing the transport of one passenger over a distance of one kilometre. It is calculated by multiplying the number of passengers by the distance each passenger travels; equivalently, it is the sum over all passenger trips of the trip distance. For example, three people traveling 5 km each contribute 15 PKMs.

PKMs are used to quantify transport activity and to compare the scale of travel across modes, regions, or time periods. They serve as a basis for estimating energy use and greenhouse gas emissions per unit of travel, planning capacity, and evaluating efficiency improvements. PKMs can be aggregated for an entire system, for a particular route, or for a given reporting period (day, month, year).

In practice, PKM is related to other measures such as tonne-kilometre for freight and passenger-miles (or passenger-mile) in regions that use miles. While PKM measures travel demand, it does not by itself capture service quality, comfort, or distribution of travel across time. Data for PKM calculation typically come from ridership counts, ticketing or farebox data, and known trip distances or average trip lengths.

PKM remains a common metric in transport planning and policy analysis, enabling comparisons of efficiency, intensity, and mode share on a common linear distance basis.