PE-Verified · Rhode Island · Massachusetts · Connecticut
Civil Engineering Calculators
Built for the Field
Free, professionally verified tools for transportation, drainage, pavement, and site design — no account, no paywall, no filler.
Available Calculators
Stopping Sight Distance
AASHTO-based SSD for level and graded roadways using design speed, grade, and PRT.
Open Calculator → TransportationHorizontal Curve Design
Computes tangent length, arc length, external distance, middle ordinate, and long chord.
Open Calculator → TransportationVertical Curve Design
Crest and sag geometry — K-value, PVC/PVT station and elevation, high/low point.
Open Calculator → Grading & SiteworkEarthwork Volume
Average end area method for cut/fill volume from cross-section data. BCY and LCY output.
Open Calculator → DrainageManning's Equation / Pipe Flow
Full-pipe capacity and velocity using Manning's n. Solves for Q or back-solves for slope.
Open Calculator → PavementAASHTO Pavement Design
Flexible pavement structural number from ESALs, reliability, DPSI, and subgrade MR.
Open Calculator → Traffic EngineeringSignal Timing (HCM)
Webster's optimal cycle length, phase splits, and critical v/c ratio for 2–4 phases.
Open Calculator → Drainage & HydrologyRational Method — Peak Runoff
Peak discharge Q = CiA for drainage areas up to 200 acres. Composite C from multiple land use types.
Open Calculator → Drainage & HydrologyTime of Concentration
Kirpich formula and TR-55 three-segment method (sheet, shallow concentrated, and channel flow).
Open Calculator → TransportationPassing Sight Distance
AASHTO 4-component PSD for two-lane highways. Computes d₁ through d₄ with speed-interpolated parameters.
Open Calculator → TransportationCurve Superelevation
Required superelevation, minimum radius, and runoff length for horizontal curves per AASHTO e+f method.
Open Calculator → DrainageCulvert Sizing
Minimum culvert diameter from Manning's equation given design Q and slope. Selects standard pipe size and checks velocity.
Open Calculator →From the Resource Center
Understanding AASHTO Stopping Sight Distance
Why perception-reaction time, friction factors, and grade each affect the design decision.
Read article → DrainageManning's Equation for Storm Drain Design
A practical guide to n values, hydraulic radius, and full-pipe vs. partial-flow analysis.
Read article → PavementAASHTO 1993 Flexible Pavement Design: Key Concepts
Structural number, ESALs, reliability, and subgrade resilient modulus explained.
Read article →