📋 Bore details
★ Fill only starred fields. All others are optional.
| Segment | Type | Lengthm, along bore | Horizontalm | Verticalm |
|---|
| Point | Chainagem | Groundelev, m | Pipeelev, m | Coverm | Requiredm | Status |
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| Point | Chainagem from entry | Elevationm | Depthbelow entry, m | Pitch |
|---|
Station–elevation table & AutoCAD export
| Pt | Stationm | Elevationm | Depthbelow entry | Groundm | Coverm | Pitch |
|---|
To draw in AutoCAD: type PLINE, press Enter, then paste the copied points (X = chainage, Y = elevation × Y-scale).
Depth = vertical depth below the entry ground level. Cover = ground (or river/canal bed) level above the pipe minus pipe level, i.e. what a walk-over locator reads directly above the head.
✅ Design checks
Rules of thumb, checked live against the design on the Basic / Advanced pages.
Minimum design radius of curvature for steel pipe pulled back by HDD.
Rmin = 1000 × OD(m) × FOS
Recommended soil cover above the pipe, based on diameter.
Pitch change the driller must make on every rod through the curves.
Δθ per rod = Lrod / R × 180/π
🛢️ Pipe specification
★ Fill only starred fields. All others are optional.
Internal volume = water needed to fill the string (ballast / hydrotest). Displaced volume includes the coating.
ID = OD − 2t Asteel = π/4 · (OD² − ID²) w = ρ · Asteel
API 5L plain-end mass: wpe = (D − t) · t · 0.02466 kg/m (D, t in mm, steel 7850 kg/m³)
Buoyant weight = wpipe + wcoat − ρmud · π/4 · ODcoated² (+ ρwater · π/4 · ID² when water-filled)
Barlow: P = 2 · S · t / D Design: P = 2 · SMYS · t · F / D Bending: σb = E · D / (2R)
🔁 Unit converter
Your value in every unit of this category. Tap a row to copy it.
| Unit | Name | Value |
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📖 How to use
- Pick the crossing type. For river, canal, road and railway crossings you give the obstacle and the minimum cover, and the app works out the minimum entry and exit setback. For Open Ground you enter the depths and plan distance yourself.
- Fill the ★ fields. Everything else is optional and has a sensible default.
- Basic gives the 5-segment profile, setbacks, cover check, node and station tables. Advanced adds the rod length and turns the same design into a rod-by-rod drilling plan, and can log as-drilled readings against it. Checks compares the design with bend-radius and cover rules of thumb.
- Use % / ° to switch how angles are entered and shown. Drillers' pitch in % = 100 × tan(angle).
- Pipe gives the pipe specification from the API 5L grade, OD, wall thickness and density: weight per metre, volumes, buoyancy in the drilling fluid and strength. The string length defaults to your design's HDD length. Units converts length, area, volume, mass, force, pressure, density, flow, velocity, torque, energy, power, temperature, angle / slope and more.
📐 Profile geometry
The bore is five sections between six points A → B → C → D → E → F: entry tangent, entry curve, horizontal bottom run, exit curve and exit tangent.
AB = H1 / sin θ1 − R1 · tan(θ1/2) EF = H2 / sin θ2 − R2 · tan(θ2/2)
BC = R1 · θ1 DE = R2 · θ2 (θ in radians)
CD = TPD − AB·cos θ1 − R1·sin θ1 − R2·sin θ2 − EF·cos θ2
HDD length = AB + BC + CD + DE + EF
The profile is feasible only if every section is ≥ 0, i.e. H1 ≥ R1(1 − cos θ1), H2 ≥ R2(1 − cos θ2), and the plan distance is long enough for both curves.
📏 Setback from cover
Level datum 0 is the bank top (river / canal) or the natural ground (road / railway). Under the obstacle the pipe must stay on or below the min-cover line:
River / canal bed: zpipe ≤ −(bed depth) − scour − Cbed
Bank slopes: zpipe ≤ ground(x) − Cbank Road / rail: zpipe ≤ −C
The bottom run is set at the lowest point of that line (plus any extra depth). If the curves can't level out that shallow — H < R(1 − cos θ) — the bottom is lowered to the geometric limit and a note is shown.
The minimum setback is the smallest horizontal distance from the entry (or exit) point to the obstacle edge for which the entry (exit) half of the bore clears the whole min-cover line. It is solved separately for each side by bisection. The pipe only gets deeper as the setback grows, so the answer is unique. Plan distance = entry setback + obstacle width + exit setback. If the two curves would overlap, both setbacks are lengthened equally until they just meet.
Fixing a setback (for a site-constrained rig position) re-runs the cover check along the full width and flags any point where the pipe is too shallow.
🔩 Rod-by-rod plan
Rod k ends at measured depth MDk = L1 + (k − 1)·L (L1 = first rod / tooling length); the last rod is shortened to finish exactly at the exit. Each rod end is placed exactly on the design path:
Tangent: x = s·cos θ, z = z0 − s·sin θ
Curve: φ = θ1 − s/R1, x = xB + R1(sin θ1 − sin φ), depth = dB + R1(cos φ − cos θ1)
Steering per rod = L / R × 180/π (“degrees per joint”)
Pitch is signed like a walk-over locator: negative = nose down. Inclination from vertical = 90° + pitch; % pitch = 100 · tan(pitch).
As-drilled readings
Logged readings use the average-angle method (as in HDD_Pilot_Master_Sheet). The tie-in is the entry angle unless you enter one:
Δawayk = Lk · cos((θk−1 + θk)/2) Δzk = Lk · sin((θk−1 + θk)/2)
Δ elev = as-drilled elevation − planned elevation at the same rod (+ = shallower than plan).
✔️ Verification
- θ = 6°, H = 6 m, R = 900 m, TPD = 1500 m → AB 10.2336, BC 94.2478, CD 1291.4936, HDD length 1500.4564 m (crossing profile geometry sheet).
- Automated HDD profile calc example (units cancel, so ft = m): entry 10°, exit 8°, R 3600, entry elev 47.1, bottom −30, exit elev 44.6, 1900 horizontal → PC1 127.08, PT1 752.22, PC2 1117.46, PT2 1618.48, pipe length 1909.54. Degrees per 31.5 joint = 0.501°.
Planning aid only — the final design must be checked and approved by a qualified engineer. Everything is calculated in your browser; nothing is uploaded.