Uploaded on 2014-12-09 by DanielMO

This photo was taken some days ago and it shows one of the entrances to the M-30 tunnels in Madrid. M-30 is the main belthighway in Madrid (Spain), the city where I live. This road, that surrounds all the ctiy center, runs almost completely underground with around 30km of tunnels, as we can see in the next map. ![enter image description here][2] The lighting, the signaling and the air renovation of the tunnels depends completely on the electric power. Without the electricity all that huge infrastructre would be unuseful. At the same time this road is crucial for the transportation of the city and their surroundings, not only in a urban manner but also in territorial scale. [1]: https://edxuploads.s3.amazonaws.com/14181096872843562.jpg [2]: https://edxuploads.s3.amazonaws.com/14181098676591767.jpg