Comparative Analysis about Development of Subterranean Transportation in Urban Spaces as a Tool to Reduce Air Pollution (CO and PM) Case Studies: Tehran and Tokyo

Air pollution is one of the major problems in the contemporary metropolis cities of developing countries. Indeed، it has happened، because of tremendous amount of private cars as media of communication in our complex urban areas. Occupation of the most of surface areas for traffic and transportation corridors and the nodes by the vehicles consuming fossil fuels، have caused air pollution. The main part of the polluted air is particulate material، and Carbon monoxide. Finally dies is and death are the dangerous result of this problem. Nowadays، due to the high volume of traffic، low level of service and congestion، long journey time، more fuel is consumed in most of the streets of Tehran. Urban spaces on the ground level under dominance of vehicles have become unsuitable area for life. Therefore، it is obvious to think of some other media of traffic and transportation that helps to get rid of all above problems. Various experiences in developed cities such as Tokyo indicates that development of subterranean corridors and nodes for mass public transport and use of electricity instead of fossil fuels are the best solution to overcome the harsh situation of air pollution which we are facing nowadays in Tehran. In this applied research، the main goal is analysis of subterranean urban space (transport corridors and nodes) features in various dimensions for reducing air pollution in capital cities like Tehran and Tokyo. The main question is how development of underground transport spaces can affect the reduction of air pollution in urban areas. This question has been answered through comparative analysis (by help of data collected through library and observation from field survey) between Tehran and Tokyo subterranean transport urban spaces. Although، there has been a lot of effort to reduce air pollution in Tehran، but by reducing the distance and time of all trips within the city، changing the fossil fuel consumption to electricity and filtration of polluted air، we can expect a better condition than what is happening right now. There are various ways to reduce travel distance of trips within a metropolitan city. Choosing the shortest roots would help reduce the journey time. But، it is very costly to implement such type of plans on ground level، in an existing situation within a built environment. Therefore، subterranean passages become more economical as far as the cost of building is concerned. Reliance on public transportation instead of private motor vehicles is another way of reducing traffic volume and congestion which can ultimately help in reducing air pollution. Building bridges and higher level of roads to create shorter distances is also another way of providing traffic and transport facilities. However، they look some kind of imposed structure to our urban environment. They visually cause problem in our urban environment. Finally، it can be concluded that Tokyo compared to Tehran has been more successful to reduce major part of air pollution (CO & PM) by development of underground great pattern of traffic and transportation. This has also caused the reduction of travel time and distance of transport within the city. Therefore، Tehran where is facing serious problem of air pollution should develop its underground public subways system instead of constructing roadways above ground level for private vehicles.