Units of transportation measurement
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The units of transportation measurement describes the units of measure to measure the quantity and traffic of transportation used in transportation statistics, planning, and their related fields.
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[edit] Units of Transportation Quantity
The currently popular units are:
[edit] Passenger
- passenger-kilometre or pkm outside the United States of America (USA);
1 pkm = (1/1.609344) pmi = 0.62137119223733396961743418436332 pmi
- passenger-mile (or pmi ?) in the USA; 1 pmi = 1.609344 pkm
[edit] Freight
- tonne-kilometre or tkm outside the USA; 1 tkm = 1 / 0.90718474 / 1.609344 tmi = 0.68494449348578545271543498886822 tmi
- ton-mile (or tmi ?) in the USA; 1 tmi = 0.90718474 * 1.609344 tkm = 1.45997231821056 tkm
[edit] Usage
Outside the USA and internationally the Metric units (pkm and tkm) are used. (In aviation where United States customary units are still widely used, the International Air Transport Association (IATA) releases its statistics in the Metric units.)
In the USA, United States customary units are used.
(Please comment on the usage in the United Kingdom.)
[edit] Derivation
The dimension of the measure is the product of payload quantity and the length.
[edit] Payload Quantity
[edit] Passenger
- passenger or person (p)
[edit] Freight
- tonne (t), a non-SI but an accepted Metric unit, defined as 1000 kilograms, is used to total the freight quantity outside the USA;
1 t = (1/0.90718474) short tons = 1.1023113109243879036148690067251 short tons.
- "short ton" is used in the USA; 1 short ton = 0.90718474 tonnes.
[edit] Length of Journey
- kilometre (km) or kilometer is a Metric unit used to measure the length of a journey outside the USA; 1 km = (1/1.609344) pmi = 0.62137119223733396961743418436332 pmi
- the international statute mile (mi) is used in the USA; 1 mi = 1.609344 km
- nautical mile is rarely used to derive units of transportation quantity.
[edit] Units of Transportation Traffic
The transportation traffic can be defined as a measure derived from the transportation quantity, with the dimension of transportation quantity divided by unit time. Often hidden as the period of totalisation, the figures appear in statistics are often quantity per unit time, say "pkm / year" or "tmi / month" . Due to the differences and variation in the lengths of months, quarters, and years, there is some ambiguity.
[edit] Units of Transportation Density
The transportation density can be defined as the payload per period, say passenger / day or tonne / day. This can be used as the measure of intensity of the transportation on a particular section or point of transportation infrastructure, say road or railway. This can be used in comparison with the constuction, running costs of the infrastructure.
[edit] External links
Here is an example of transportation statistics.
