WHY ALL IMPORTANT PAVEMENTS SHOULD BE WELL DRAINED

During the hours, days, and months that pavements are filled with water, heavy vehicle loads cause severe damaging actions such as erosion and pumping, disintegration of cement-treated bases, stripping of asphalt coatings from bituminous-treated bases and subbases, and overstressing of weakened subgrades. The presence of liberal amounts of water causes or increases non-load-bearing damage such as D-cracking, blow-up, frost action, expansion, shrinkage cracking, accelerated oxidation and loss of flexibility, and general deterioration of pavements and bases. Pavements designed without fast internal drainage can stay filled with water during much of the year while they are also subjected to damaging environmental conditions. If pavements are provided with fast internal drainage, water-related damage is almost entirely eliminated, which increases pavement life substantially and saves billions of dollars a year in the United States alone. Even though the need for good drainage and the benefits it can provide have been known for centuries, few modern pavement designers use it. In this author's view, the best methods available should be used in designing pavements, and in addition every important pavement should be provided with an internal drainage system capable of rapidly removing all water that enters.