Methods for Predicting Urban Drainage Costs

Examination of over 100 small urban drainage systems reveals that investment in conventional drainage systems depends upon design factors and physical characteristics of the drainage area. The average slope of the drainage area, smallest diameter of pipe, number of inlets and manholes, storm frequency, runoff coefficient, total capacity, and total developed area are the most significant cost components. Regression, multivariant, and nonlinear techniques are used to explain differences in design methods and to develop cost prediction equations for various levels of design. Such prediction models will enable agencies such as the Federal Housing Administration and municipal and regional planning commissions, as well as engineering offices, to judge the cost of design alternatives rapidly and reasonably accurately.