Uploaded on 2014-11-28 by dakou

[1]: https://edxuploads.s3.amazonaws.com/14171974103381624.jpg The photo is from the metro station "Agios Dimitrios" in Athens, Greece. Transportation constitutes a key infrastructure of the 21st century city. Citizens depend on public transport for movement through the urban space. As urban systems extend, the range of commuting increases. Distance between the residence place, the work place, the entertainment place, expands. We need to travel long distances in no time everyday. Fixed rail means of transport in particular, are essential for contemporary cities due to three parameters: low pollutant emitted, minimum intervention in urban image and energy saving. As a consequence, they contribute to environmental and life quality upgrade. Subway even more particularly, because of the space saving and velocity it can provide, forms an integral part of today cities. It should definitely be considered as a key factor of urban transportation in future cities.