CCWI2017: F120 'Costs Functions Proficiency over the Urban Drainage Networks Optimal Design' DuqueNatalia AguilarAndrés SaldarriagaJuan 2017 The urban drainage networks optimal design objective function must represent accurately the real construction costs of these systems. This design problem involves two sub problems which require a specific cost function. For the layout selection problem, a cost function in terms of the flow rate and direction is needed, since there is no information about the diameter, depth, and slope of the pipes. A good estimation of the layout cost function is needed to find the minimum-cost urban drainage network design. The optimal hydraulic design of the network requires the best layout selection. In this paper some cost functions are tested using the urban drainage network optimal design methodology proposed by Duque N. et al. (2015) [1], on part of a real network located in Bogota, Colombia. Afterwards, a sensitivity analysis is performed to determine the effect of each cost function over the layout selection and hydraulic design of the network. Moreover, this analysis aims to evaluate the cost functions proficiency and robustness, when changing parameters such as the filling ratio and the pipes material. <br>