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.

Length of Journey

• kilometre
  Kilometre
  The kilometre is a unit of length in the metric system, equal to one thousand metres and is therefore exactly equal to the distance travelled by light in free space in of a second...
  
   (km) or kilometer is a Metric unit used to measure the length of a journey outside the USA;
• the international statute mile (mi) is used in the USA; 1 mi = 1.609344 km
• nautical mile
  Nautical mile
  The nautical mile is a unit of length that is about one minute of arc of latitude along any meridian, but is approximately one minute of arc of longitude only at the equator...
  
   is rarely used to derive units of transportation quantity.

Passenger-distance

Passenger-distance is the distance (km or miles) traveled by passengers on transit vehicles; determined by multiplying the number of unlinked passenger trips by the average length of their trips.

• passenger-kilometre or pkm internationally;
• passenger-mile (or pmi ?) sometimes in the USA; 1 pmi = 1.609344 pkm

Passengers per bus hour

A system may carry a high number of passengers per distance (km or mile) but a relatively low number of passengers per bus hour if vehicles operate in congested

Congestion

Congestion generally means excessive crowding.Congestion may refer to:* congestion in heart failure, a term to describe low cardiac output seen in heart failure.* Nasal congestion, the blockage of nasal passages due to swollen membranes...

 areas and thus travel at slower speed.

Passengers per bus distance

A transit system serving a community with a widely dispersed population must operate circuitous routes that tend to carry fewer passengers per distance (km or mile). A higher number is more favorable

Freight

A simple unit of freight is the kilogram-kilometer (kgkm), the service of moving one kilogram of payload a distance of one kilometer.

Payload Quantity

• kilogram
  Kilogram
  The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
  
   (kg), the standard SI
  International System of Units
  The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units...
  
   unit of mass.
• tonne
  Tonne
  The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
  
   (t), a non-SI
  International System of Units
  The International System of Units is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten. The older metric system included several groups of units...
  
   but an accepted Metric unit, defined as 1,000 kilogram
  Kilogram
  The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
  
  s.
• "short ton" is used in the USA; 1 short ton = 2,000 pounds
  Pound (mass)
  The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...
  
   = 0.907 185 tonnes.

1 t = (1/0.907 185) short ton

Short ton

The short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...

s = 1.102 311 short tons.

Payload-Distance

• kilogram-kilometer or kgkm, moving 1 kg of cargo a distance of 1 km;
• tonne-kilometre or tkm; 1 tkm = 1,000 kgkm;
• ton-mile (or tmi ?) in the USA: 1 ton-mile * ( 0.907 185 t / ton) * ( 1.609 344 km / mile ) = 1.459 973 tkm
• Kilometre-ton (unit: kmt) — the transportation of one metric ton
  Tonne
  The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
  
   over one kilometre
  Kilometre
  The kilometre is a unit of length in the metric system, equal to one thousand metres and is therefore exactly equal to the distance travelled by light in free space in of a second...
  
  

Usage

Outside the USA and internationally the Metric

Metric system

The metric system is an international decimalised system of measurement. France was first to adopt a metric system, in 1799, and a metric system is now the official system of measurement, used in almost every country in the world...

 units (pkm and tkm) are used.
(In aviation

Aviation

Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...

 where United States customary units

United States customary units

United States customary units are a system of measurements commonly used in the United States. Many U.S. units are virtually identical to their imperial counterparts, but the U.S. customary system developed from English units used in the British Empire before the system of imperial units was...

 are still widely used,
the International Air Transport Association

International Air Transport Association

The International Air Transport Association is an international industry trade group of airlines headquartered in Montreal, Quebec, Canada, where the International Civil Aviation Organization is also headquartered. The executive offices are at the Geneva Airport in SwitzerlandIATA's mission is to...

 (IATA) releases its statistics in the Metric units.)

In the USA, sometimes United States customary units are used.

(Please comment on the usage in the United Kingdom.)

Derivation

The dimension of the measure is the product of the quantity of payload mass and the distance transported.

Example

A semi truck

Semi-trailer truck

A semi-trailer truck, also known as a semi, tractor-trailer, or articulated truck or articulated lorry, is an articulated vehicle consisting of a towing engine , and a semi-trailer A semi-trailer truck, also known as a semi, tractor-trailer, or (in the United Kingdom and Ireland) articulated truck...

traveling from Los Angeles to Chicago (approximate distance 2,015 miles) carrying 14 short tons of cargo delivers a service of 14 * 2,015 = 28,210 ton-miles of freight (equal to about 41,186 tkm).

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.

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 construction, running costs of the infrastructure.

External links

Here is an example of transportation statistics.

• Scheduled Passengers Carried, World Air Transport Statistics 51st Edition, IATA