 sustainable transport refers to the broad subject of transport that is sustainable in the senses of social, environmental and climate impacts and the ability to, in the global scope, supply the source energy indefinitely. components for evaluating sustainability include the particular vehicles used for road, water or air transport; the source of energy; and the infrastructure used to accommodate the transport (roads, railways, airways, waterways, canals and terminals). another component for evaluation is pipelines for transporting liquid or gas materials. transport operations and logistics as well as transit-oriented development are also involved in evaluation. transportation sustainability is largely being measured by transportation system effectiveness and efficiency as well as the environmental and climate impacts of the system. short-term activity often promotes incremental improvement in fuel efficiency and vehicle emissions controls while long-term goals include migrating transportation from fossil-based energy to other alternatives such as renewable energy and use of other renewable resources. the entire life cycle of transport systems is subject to sustainability measurement and optimization. sustainable transport systems make a positive contribution to the environmental, social and economic sustainability of the communities they serve. transport systems exist to provide social and economic connections, and people quickly take up the opportunities offered by increased mobility.schafer, a. (1998) "the global demand for motorized mobility." transportation research a 32(6), 455-477. the advantages of increased mobility need to be weighed against the environmental, social and economic costs that transport systems pose. transport systems have significant impacts on the environment, accounting for between 20% and 25% of world energy consumption and carbon dioxide emissions.">{{cite web |url=http://www.worldenergy.org/publications/809.asp|title=transport technolog
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