Transport infrastructure - highways, railways, ports and waterways, and airports and air traffic control systems - and the services that flow from it are crucial to the activities of households, producers, and governments. Because performance indicators vary widely by transport mode and focus (whether physical infrastructure or the services flowing from that infrastructure), highly specialized and carefully specified indicators are required to measure a country's transport infrastructure.

The railway transport industry a vital engine of global socio-economic growth. It is of vital importance for economic development, creating direct and indirect employment, supporting tourism and local businesses. Economic growth, technological change, and market liberalization affect road transport throughout the world.

Railways have helped in the industrialization process of a country by easy transportation of coal and raw-materials at a cheaper rate. As railways require huge capital outlay, they may give rise to monopolies and work against public interest at large. Even if controlled and managed by the government, lack of competition sometimes results in inefficiency and high costs. Also, many times it is not economical to operate railways in sparsely settled rural areas. Thus, in many developing countries large rural areas have no railway even today.

Rail transport is a major form of passenger and freight transport in many countries. Passenger trains can involve a variety of functions including long distance travel, daily commuter trips, or local urban transit services. Railways are very popular mode of transportation in Europe, with an integrated network covering virtually the whole continent. In India, China, South Korea and Japan, many millions use trains as regular transport. In North America, freight rail transport is widespread and heavily used in for transporting goods. The western Europe region has the highest railway density in the world and has many individual trains which operate through several countries despite technical and organizational differences in each national network. Australia has a generally sparse network, mostly along its densely populated urban centers.
Railways, passengers carried (million passenger-km)
Unlike the road sector, where numerous qualified motor vehicle operators can operate anywhere on the road network, railways are a restricted transport system with vehicles confined to a fixed guideway. Considering the cost and service characteristics, railways generally are best suited to carry - and can effectively compete for - bulk commodities and containerized freight for distances of 500-5,000 kilometers, and passengers for distances of 50-1,000 kilometers. Below these limits road transport tends to be more competitive, while above these limits air transport for passengers and freight and sea transport for freight tend to be more competitive. 

Data for transport sectors are not always internationally comparable. Unlike for demographic statistics, national income accounts, and international trade data, the collection of infrastructure data has not been "internationalized."
Passengers carried by railway are the number of passengers transported by rail multiplied by kilometers traveled.
Passenger-kilometers are usually measured on the basis of the rail travel distance between origin and destination multiplied by the number of passengers traveling between each origin and destination.