This volume presents results of tests conducted on slotted drain inlets. Tests were conducted to study the effect of individual parameters on the efficiency of slotted drains. Total flow capture tests were done at full scale for various roadway roughnesses, types of transverse spacer bars, slot widths, distances from curb to slot, and combinations of flow and slope conditions. Additional tests were conducted to investigate partial flow interception capacity, sheet flow interception capacity, interception capacity of slot in a sump condition, and relative debris handling ability of slotted drain in a sump condition and on a grade. Design procedures for 1.75-in (44.45 mm) wide slots with solid vertical transverse bars at 6-in (152.4-mm) spacing, installed 3.5 in (88.9 mm) from the curb face (Sv-1.75-6-3.5) are given in the form of graphs and equations. The total flow capture length (L) is controlled by weir flow in most cases. However, at steep slopes and high flows, an inefficient submerged flow condition controls L. Equations defining L in the weir flow and submerged flow zones for an SV-1.75-6-3.5 slot installation are given. Slotted drain is a more efficient flow interceptor in the upstream region; therefore it is more efficient to capture most of the flow in a short length of slot and pass the remaining flow onto a downstream collection point. A partial flow capture design method is given for an SV-1.75-6-3.5 installation. A general design procedure covering a wider range of slot installations will be given in volume 5. (Author/publisher)
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