Surface Water Drainage
Water is the most important compound ensuring life on earth, but on roads the presence of water means mainly trouble. A main cause of road damage, and problems with the serviceability of road networks, is excess water filling the pores of road materials in the road and in the subgrade soils.
It is generally known that road structures operate well in dry conditions and because of this, roads historically have been built on dry terrain. On those occasions where roads have had to be built on wet terrain, drainage structures have usually been designed to keep the road structures dry.