Enhanced method for estimation of flow intercepted by drainage grate inlets on roads

Determining appropriate road drainage grate installation intervals requires an equation for estimating the flow intercepted by each grate inlet and its interception efficiency. In this study, 720 experiments were performed using a hydraulic model to estimate the flow intercepted by a grate inlet on a road. The flow calculation considered the number of lanes (2–4), longitudinal slope of the road (2–10%), transverse slope of the gutter (2–10%), and design capacity (up to 30 years of rainfall). The experimental results revealed that the flow intercepted by a grate inlet increased with increasing transverse slope of the gutter or the inlet length, thereby increasing its interception efficiency. Intercepted flow estimation equation was derived by regression analysis, and the derived equation was found to be more accurate than an existing empirical equation. The derived equation can thus be used to determine the installation of drainage grate inlets more effectively.