Generalities
Amongst urban utilities, water supply, waste water disposal and drainage of rainwater are, since ancient times, prevailing activities in underground space of main cities.
New needs are created by urban development and the fight against floods and pollution lead to new projects.
Since the development of gas in the cities ducts have always been burried under the roads. The main aspect in this case is the protection against incident which could lead to explosions.
New ducts are being developped underground it is the case of penumatic waste ducts.
