IntroductionOne of the most important factors in the construction of a road is drainage. If every other aspect of road design and construction is done correctly but road drainage is not well planned, designed and constructed, the road structure will inevitably lead to premature failure. Erosion control is an integral part of road drainage. Excessive erosion can block culverts leading to saturation of the road pavement structure and failure of drainage systems, ultimately leading to pavement failure. Unpaved roads are extremely vulnerable to flooding, landslides and gully erosion. According to information available from the Pavement Management Branch of the Ethiopian Road Authority, water-related damage accounted for more than 35 percent of defects in federal paved roads and 60 percent of defects in unpaved roads reported from 2000 to 2002. L ERA also reports that floods following torrential rain cause frequent landslides and washouts of drainage structures. It is very important to provide guidance on how to incorporate erosion control mechanisms i...