Culvert Hydraulic Design (Preliminary)
Ref: MSMA 2nd Edition (2012), Chapter 18 — Culvert (based on FHWA HEC-5)
Q = (1/n) × A × R^(2/3) × S^(1/2) × N (full-flow / outlet control)
Ref: MSMA 2nd Edition (2012), Chapter 18 — Culvert (based on FHWA HEC-5)
A = B×D | P = 2(B + D)
Box culvert (RCBC)
A = π·d²/4 | P = π·d
Pipe culvert (RCP)
Culvert Type
Culvert Properties
MSMA Table 2.3 — Concrete pipe 0.013, uPVC 0.011, CMP 0.024
Typical 0.005–0.02, match drain invert
Single, twin, or triple barrel
Dimensions
Internal clear width
Internal clear height
Adequacy Check (Optional)
Optional — from Rational Method for adequacy check
Flow Area per Barrel (A)
—m²
Engineering aid only — final design must be endorsed by a registered PE under BEM.
Wetted Perimeter (P)
—m
Engineering aid only — final design must be endorsed by a registered PE under BEM.
Hydraulic Radius (R)
—m
Engineering aid only — final design must be endorsed by a registered PE under BEM.
Flow Velocity
—m/s
Engineering aid only — final design must be endorsed by a registered PE under BEM.
Capacity per Barrel
—m³/s
Engineering aid only — final design must be endorsed by a registered PE under BEM.
Total Culvert Capacity
—m³/s
Engineering aid only — final design must be endorsed by a registered PE under BEM.