Sustainable transport
Sustainable transport is transportation sustainable in terms of its social and environmental impacts. Components for evaluating sustainability include the particular vehicles used; the source of energy; and the infrastructure used to accommodate the transport. Transportation sustainability is largely being measured by transportation system effectiveness, efficiency, and the environmental and climate impacts of the system. Transport systems have significant impacts on the environment. In 2018, it contributed to around 20% of global CO2 emissions. Greenhouse gas emissions from transport are increasing at a faster rate than any other energy using sector.
A 2023 study published in Journal of Transport Geography found that shared electric bicycle systems reduce urban transport-related carbon emissions by about 108–120 grams per kilometer, particularly in non-central urban areas and when powered by low-carbon electricity sources.
Road transport is also a major contributor to local air pollution and smog.
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, with poor households benefiting greatly from low carbon transport options. The advantages of increased mobility need to be weighed against the environmental, social and economic costs that transport systems pose. Short-term activity often promotes incremental improvement in fuel efficiency and vehicle emissions controls. 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.
The United Nations Environment Programme estimates that each year 2.4 million premature deaths from outdoor air pollution could be avoided. Particularly hazardous for health are emissions of black carbon, a component of particulate matter, which is a known cause of respiratory and carcinogenic diseases and a significant contributor to global climate change. The links between greenhouse gas emissions and particulate matter make low carbon transport an increasingly sustainable investment at local level—both by reducing emission levels and thus mitigating climate change; and by improving public health through better air quality. The term "green mobility" also refers to clean ways of movement or sustainable transport.
The social costs of transport include road crashes, air pollution, physical inactivity, time taken away from the family while commuting, and vulnerability to fuel price increases. Many of these negative impacts fall disproportionately on those social groups who are also least likely to own and drive cars. Traffic congestion imposes economic costs by wasting people's time and by slowing the delivery of goods and services. Traditional transport planning aims to improve mobility, especially for vehicles, and may fail to adequately consider wider impacts. But the real purpose of transport is access – to work, education, goods and services, friends and family – and there are proven techniques to improve access while simultaneously reducing environmental and social impacts, and managing traffic congestion. Communities which are successfully improving the sustainability of their transport networks are doing so as part of a wider program of creating more vibrant, livable, sustainable cities.
Definition
The term sustainable transport came into use as a logical follow-on from sustainable development, and it describes modes of transport, and systems of transport planning, which are consistent with wider concerns of sustainability. There are many definitions of the sustainable transport, and of the related terms sustainable transportation and sustainable mobility. One such definition, from the European Union Council of Ministers of Transport, defines a sustainable transportation system as one that:- Allows the basic access and development needs of individuals, companies and society to be met safely and in a manner consistent with human and ecosystem health, and promotes equity within and between successive generations.
- Is affordable, operates fairly and efficiently, offers a choice of transport mode, and supports a competitive economy, as well as balanced regional development.
- Limits emissions and waste within the planet's ability to absorb them, uses renewable resources at or below their rates of generation, and uses non-renewable resources at or below the rates of development of renewable substitutes, while minimizing the impact on the use of land and the generation of noise.
Benefits
Sustainable transport has many social and economic benefits that can accelerate local sustainable development. According to a series of serious reports by the Low Emission Development Strategies Global Partnership, sustainable transport can help create jobs, improve commuter safety through investment in bicycle lanes, pedestrian pathways and non-pedestrian pathways, make access to employment and social opportunities more affordable and efficient. It also offers a practical opportunity to save people's time and household income as well as government budgets, making investment in sustainable transport a 'win-win' opportunity.Environmental impact
Transport systems are major emitters of greenhouse gases, responsible for 23% of world energy-related GHG emissions in 2004, with about three-quarters coming from road vehicles. Data from 2011 stated that one-third of all greenhouse gases produced are due to transportation. Currently 95% of transport energy comes from petroleum. Energy is consumed in the manufacture as well as the use of vehicles, and is embodied in transport infrastructure including roads, bridges and railways. Motorized transport also releases exhaust fumes that contain particulate matter which is hazardous to human health and a contributor to climate change.The first historical attempts of evaluating the Life Cycle environmental impact of vehicle were due to Theodore Von Karman. After decades in which all the analysis has been focused on emending the Von Karman model, Dewulf and Van Langenhove have introduced a model based on the second law of thermodynamics and exergy analysis. Chester and Orwath, have developed a similar model based on the first law that accounts the necessary costs for the infrastructure.
The environmental impacts of transport can be reduced by reducing the weight of vehicles, sustainable styles of driving, reducing the friction of tires, encouraging electric and hybrid vehicles, improving the walking and cycling environment in cities, and by enhancing the role of public transport, especially electric rail.
Green vehicles are intended to have less environmental impact than equivalent standard vehicles, although when the environmental impact of a vehicle is assessed over the whole of its life cycle this may not be the case.
Electric vehicle technology significantly reduces transport CO2 emissions when comparing battery electric vehicles with equivalent internal combustion engine vehicles. The extent to which it does this depends on the embodied energy of the vehicle and the source of the electricity. Lifecycle greenhouse gas emission reductions from BEVs are significant, even in countries with relatively high shares of coal in their electricity generation mix, such as China and India. As a specific example, a Nissan Leaf in the UK in 2019 produced one third of the greenhouse gases than the average internal combustion car.
File:IEA_average_lifetime_emissions_for_vehicles_sold_in_2019.png|upright=2.5|right|alt=Chart comparing lifecycle greenhouse gas emissions for various vehicle types|thumb|Battery electric vehicles have lower lifecycle emissions than other vehicle types. Abbreviations used in this chart: - ICE: internal combustion engine vehicle, CNG: compressed natural gas, HEV: hybrid electric vehicle, BEV: battery electric vehicle, PHEV: plugin hybrid electric vehicle, FCEV: fuel cell vehicle, STEPS: IEA's Stated Policies Scenario, APS: IEA's Announced Pledges Scenario, NZE: IEA's Net Zero Emissions by 2050 Scenario.
The Online Electric Vehicle, developed by the Korea Advanced Institute of Science and Technology, is an electric vehicle that can be charged while stationary or driving, thus removing the need to stop at a charging station. The City of Gumi in South Korea runs a 24 km roundtrip along which the bus will receive 100 kW electricity at an 85% maximum power transmission efficiency rate while maintaining a 17 cm air gap between the underbody of the vehicle and the road surface. At that power, only a few sections of the road need embedded cables. Hybrid vehicles, which use an internal combustion engine combined with an electric engine to achieve better fuel efficiency than a regular combustion engine, are already common.
Natural gas is also used as a transport fuel, but is a less promising technology as it is still a fossil fuel and still has significant emissions.
Brazil met 17% of its transport fuel needs from bioethanol in 2007, but the OECD has warned that the success of biofuels in Brazil is due to specific local circumstances. Internationally, first-generation biofuels are forecast to have little or no impact on greenhouse emissions, at significantly higher cost than energy efficiency measures.
The later generation biofuels however do have significant environmental benefit, as they are no driving force for deforestation or struggle with the food vs fuel issue.
In practice there is a sliding scale of green transport depending on the sustainability of the option. Green vehicles are more fuel-efficient, but only in comparison with standard vehicles, and they still contribute to traffic congestion and road crashes. Well-patronized public transport networks based on traditional diesel buses use less fuel per passenger than private vehicles, and are generally safer and use less road space than private vehicles. Green public transport vehicles including electric trains, trams and electric buses combine the advantages of green vehicles with those of sustainable transport choices. Other transport choices with very low environmental impact are cycling and other human-powered vehicles, and animal powered transport. The most common green transport choice, with the least environmental impact is walking.
Transport on rails boasts an excellent efficiency.