Cross-drainage&culvert design on highways

One of the most important considerations of the location and design of rural highways is the necessity for providing adequate drainage. Highway drainage may be generally defined as the process of controlling and taking away excess surface and subsurface water from the road structure in order to prevent any damage on it. Cross drainage, on the other hand, involves the conveyance of surface water and stream flow across or from the highway right of way. Highway culverts are used to transport water under a highway to allow water to continue to a natural water source (e.g., a river or lake). Culverts are usually considered minor structures, but they are of great importance to adequate drainage and the integrity of the highway facility. Many different inlet and outlet configurations are used on culvert barrels to reduce erosion, inhibit seepage, retain the fill, improve the aesthetics and hydraulic characteristics and make the ends structurally stable. Futhermore, in order for an efficient and economic operation of a culvert within a drainage system, culverts should be located properly and the required length for a culvert should be selected carefully. Regardless of the size or cost of the drainage feature, the most important step prior to hydraulic design is estimating the discharge (rate of flow) or volume of runoff that the drainage facility will be required to convey or control, and cross drainage design normally requires more extensive hydrologic analysis than is necessary for roadway drainage design. Having estimated the design discharge to be conveyed, the next step is the hydraulic design of a culvert that consists of an analysis of the performance of the culvert in conveying flow from one side of the roadway to the other.Ill In this thesis work, hydrologic and hydraulic considerations for culverts are mentioned together with some general features related to culverts and an alternative culvert design procedure compiled from national and international literature is proposed based on all these mentioned criteria. In addition, to illustrate the real phenomenon, certain culvert locations throughout Aydin-Denizli Highway are selected and re-designed both by hand calculation and by using three related softwares, and the results obtained are compared in the end.