Flexible pavements are those pavements which reflect the deformation of subgrade and the subsequent layers to the surface. Flexible, usually asphalt, is laid with no reinforcement or with a specialized fabric reinforcement that permits limited flow or re positioning of the roadbed under ground changes. The design of flexible pavement is based on load

The quantity of water available at the source must be sufficient to meet various demands and requirements of the design population during the entire design period. Plans should be made to bring water from other sources if the available water is insufficient. The water available at the source must not be toxic, poisonous or in anyway injurious to health. The impurities

The quantity of water available at the source must be sufficient to meet various demands and requirements of the design population during the entire design period. Plans should be made to bring water from other sources if the available water is insufficient.

Hardness is the property that makes water require more soap to produce a foam or lather. The hardness of water is not harmful to human health but can be precipitated by heating so can produce damaging effects in boilers, hot pipes, etc by depositing the material and reducing the water storage and carrying capacity. Absolute soft water on the other hand is not acceptable

Collection of domestic wastewater is best achieved by a full sewerage water drain age system. Unfortunately this method is most expensive and there is relatively few communities in hot climate which afford it. A modern hygienic method of night soil collection is the only realistic alternative. Treatment is required principally to destroy pathogenic agents in sewage or night