Source: adapted from UK Department of the Environment, Transport and the Regions, 1999.
The concept of sustainable transportation is intricately linked with the development of sustainable transport modes, infrastructures and operations. Similar to the concept of sustainable development, three major dimensions are considered:
- Environment. A reduction of the environmental impacts of transportation is a likely strategy for sustainability. Transportation contributes to harmful emissions, noise, and climate change. About 15% of the total greenhouse gases and 22% of the CO2 emissions are attributed to transportation. However, as vehicles are becoming more environmentally efficient, the global fleet of vehicles is increasing as well. An improvement of the land use impacts of transportation, especially the impacts of infrastructure construction and maintenance, is also a strategic goal to achieve. Transportation systems are also waste generators (vehicles, parts, packaging, etc.) that must be reduced, reused, and recycled.
- Economy. Transportation is a factor of economic growth, development, and employment. It requires materials for modes and infrastructure and energy for operations, which can be used more efficiently. Transportation should also have a fair pricing strategy, meaning that users bear the full costs (direct and indirect) of their usage of the transport system. A transport system where competition is fair and open is likely to promote modal choice and efficiency. In a system where transport is a public or private monopoly, price distortions and misallocations of capital are created, which in the long run are likely to render the system unsustainable.
- Society. Sustainable transportation should benefit society. It should be safe, not impairing human health, and should minimize disturbance in communities. Access and equity are also two important principles as transportation should promote access to goods and services for as many people as possible.
The matter is often that reconciling all these principles, which individually appear logical and straightforward, may lead to unsustainable transportation systems because they are too costly and regulated.