Interactive engineering model
Curb inlet interception and bypass
Adjust gutter flow and inlet geometry to see spread, captured flow, and bypass continue along the roadway.
Preparing the 3D model...
A kerbed roadway section carries a triangular gutter wedge into a curb opening whose length is set by the inlet-length control. Across the opening the wedge tapers along the HEC-22 efficiency curve, water falls through the throat into a cutaway catch basin with a sump and an outlet pipe, and the remaining flow leaves at the spread its own bypass discharge produces - which is nothing at all when interception is total. Numeric labels report intercepted and bypass discharge, and the section is drawn at a stated vertical exaggeration.
Focus the 3D view and use the arrow keys to orbit, plus or minus to zoom, and Home to reset the view.
Text explanation and non-WebGL fallback
A kerbed roadway section carries a triangular gutter wedge into a curb opening whose length is set by the inlet-length control. Across the opening the wedge tapers along the HEC-22 efficiency curve, water falls through the throat into a cutaway catch basin with a sump and an outlet pipe, and the remaining flow leaves at the spread its own bypass discharge produces - which is nothing at all when interception is total. Numeric labels report intercepted and bypass discharge, and the section is drawn at a stated vertical exaggeration.
Important: On-grade curb-opening inlets only. This artifact does not cover grate, combination, or slotted inlets, or any inlet in a sag; use the calculator for those cases.
The numeric controls and readouts remain usable if WebGL is unavailable. Drag or swipe the 3D view to orbit and use a wheel or pinch gesture to zoom. With the 3D view focused, use the arrow keys to orbit, plus or minus to zoom, and Home to reset. The complete numeric lesson is also keyboard-accessible in the adjacent controls and readouts. This model is an educational aid and does not replace applicable design standards or professional review.