The objective of urban storm drainage is to provide safe passage of vehicle traffic by collecting stormwater from the roadway, and to convey it safely to an adequate receiving body while preventing damage to adjacent private properties or undue risk to pedestrian traffic during the design storm event.

Appropriate longitudinal and transverse slopes can serve to move water off the travel way to minimize ponding, sheet flow, and low crossovers. This means that the hydraulic designer must work with the roadway geometric designer to assure efficient drainage in accordance with the geometric and pavement design.