<P> Transportation is a large contributor to greenhouse gas emissions . It is said that one - third of all gasses produced are due to transportation . Motorized transport also releases exhaust fumes that contain particulate matter which is hazardous to human health and a contributor to climate change . </P> <P> Sustainable transport has many social and economic benefits that can accelerate local sustainable development . According to a series of reports by the Low Emission Development Strategies Global Partnership (LEDS GP), sustainable transport can help create jobs, improve commuter safety through investment in bicycle lanes and 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 . </P> <P> Some Western countries are making transportation more sustainable in both long - term and short - term implementations . An example is the modification in available transportation in Freiburg, Germany . The city has implemented extensive methods of public transportation, cycling, and walking, along with large areas where cars are not allowed . </P> <P> Since many Western countries are highly automobile - oriented, the main transit that people use is personal vehicles . About 80% of their travel involves cars . Therefore, California, is one of the highest greenhouse gases emitters in the United States . The federal government has to come up with some plans to reduce the total number of vehicle trips in order to lower greenhouse gases emission . Such as: </P>

Define sustainable development give two important principle in this respect