Hydrological Survey and Design of Small Bridges and Culverts

9.1.1 In accordance with terrain, geology, hydrology and other conditions along the route and considering the drainage system in the whole route, small bridges and culverts shall be laid out economically and properly to adapt to irrigation and drainage of farmland, and to achieve the drainage ability corresponding to the design flood frequency, which is specified in Clause 1.0.8 of the Specifications.