It is obvious that the improvement of urban transport is an important and effective factor in urban life quality and it has a close relationship with air pollution and greenhouse gasses.  Public transport system is developing more than before 20th century and it changes and innovates every day. Currently, more than 24 billion transports, more than three times of the Earth population, occur with public transport and more than 13 million people are employed in this sector.

If we promote public transport capacity to double the current, 170 million tons oil will be saved annually at global scale. It will also reduce half billion tons carbon dioxide by 2015. Travelling by private car inserts greenhouse gasses into the atmosphere 3.5 times greater per kilometer.

Globally, the highest per capita trip with public transport is Switzerland with 237 trips. Sweden, Germany, Belgium are next in line. On a smaller scale, most of the sustainable cities in the world have modern, smart and sustainable public transport. For example, Vienna has one of the most advanced and extensive public transport and among developing countries, Curitiba in Brazil, is a good example of public transport extension.

The important point is that urban managers in most of the developing countries put models based on automobile-oriented models in their agenda. They constantly strengthen infrastructures related to private transport including building highways as Lewis Mumford; urban planner said adding lanes to solve traffic congestion are like loosening your belt to solve obesity.

Moreover, urban transport is one of the sectors that it adds increasingly its share on air pollutants. Generally, transport is the second large carbon dioxide producing in the world and more than 23% of carbon dioxide emission in the world is related to this sector.

In Iran, Tehran metropolis put sustainable public transport on its agenda in line with its long-term goals in order to achieve urban sustainable development and fulfilled this goal by expanding metro lines. Today, Tehran subway, with movement capacity about 3 million passengers per day, plays an important role in order to reduce traffic and air pollution, and develop urban sustainability. Opening Tehran subway- line 3, with 37 km length as the longest subway line in the Middle East is a step toward achieving this goal.

 Source : Mehr news agency