What is the difference between inlet and outlet control?

Inlet control: culvert capacity limited by inlet geometry (headwater depth, entrance type). Outlet control: capacity limited by full pipe conditions, tailwater, and friction. Design for whichever gives lower capacity.

What headwater to diameter ratio is acceptable?

Maximum HW/D = 1.0-1.5 for typical crossings. Higher ratios require upstream ponding. For fish passage, maximum HW/D = 0.75 and minimum depth ≥ 0.3m at design low flow.

What inlet treatment reduces headwater depth?

Beveled edges, tapered inlets, and projecting cut-off walls improve inlet hydraulics. FHWA HEC-5 provides inlet improvement factors reducing required headwater by 20-40%.

Culvert Design Calculator

Design culvert for inlet and outlet control conditions. HW/D ratio for headwater depth. Culvert capacity charts for circular, box, and elliptical sections. Fish passage minimum velocity and depth requirements.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How to Use

Enter the values for the patient or scenario you are assessing. Design culvert for inlet and outlet control conditions. HW/D ratio for headwater depth. Culvert capacity charts for circular, box, and elliptical sections. Fish passage minimum velocity and depth requirements. Use the culvert design result to inform your clinical assessment.

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Frequently Asked Questions

What is the difference between inlet and outlet control?

What headwater to diameter ratio is acceptable?

What inlet treatment reduces headwater depth?