Design Brief
Pick the pavement type, state the problem, and the tool finds the cheapest section that satisfies every IRC:37-2018 criterion.
IRC:37-2018 Cl. 9.2 defers to MoRTH (5th Rev.) for layer minimums:
• BC — Cl. 507: min 30 mm (Grading 2)
• DBM — Cl. 505.1 / Table 500-10: min 50 mm (Grading 2)
• BM — Cl. 504.1 / Table 500-7: min 50 mm (Grading 2)
Typical combined BC+DBM section ≈ 100 mm or more.
⚠ Caution: these are per-layer construction minimums by aggregate grading — not a single design value. The tool treats the bituminous as one combined layer (per IRC structural analysis); set the figure below to your chosen section's total, and verify the BC/DBM split separately against MoRTH. Enter 0 to use the type default.
Material Rates (per m³)
Enter your actual rates so the result is a real cost per m². Leave all at 0 to use a relative ranking score instead. The rate boxes below match the layers of the selected pavement type.
Recommended Section
Design Traffic — IRC:37‑2018 (MSA)
Compute cumulative standard axles (MSA) from traffic counts, then send the result to the Analyze tab. You can always type your own MSA there instead — this tab is an optional helper, never a gate.
Enter each vehicle class with its base-year count, its VDF, and the growth-rate bands. A growth band means "this rate % applies up to year Y"; the last band applies to all later years. The values below are pre-filled with a worked example you can edit or replace.
| Class | Base count | VDF | Growth bands (rate%@upto_year, comma-sep) |
|---|
Loading
Mix & reliability
Pavement layers top → bottom; last row is subgrade
| # | Name | Type | E (MPa) | Poisson ν | Thickness (mm) |
|---|
A modulus shown with a 🔒 lock is filled automatically from IRC:37-2018 Table 11.1 (unbound granular layers use Eq. 7.1, the subgrade uses Eq. 6.1 from CBR). To type your own value instead, click the small edit link next to that modulus.
Computed response
Stress vs depth
Show data table
Surface deflection bowl
Show data table
Sensitivity — bituminous thickness vs design life
Show data table
CTB Cumulative Fatigue Damage (Eq. 3.6 / 3.7)
Detailed cement-treated-base fatigue over the axle-load spectrum, for the semi-rigid (Fig 3.2) section. Shows both this engine's precise value and the IRC‑37:2018 two-decimal (book) value side by side. CFD < 1.0 is safe.
Section layers (top to bottom; last row = subgrade, no thickness). Defaults are the Annex II.4 worked example.
| Name | E (MPa) | ν | h (mm) |
|---|
Axle-load spectrum (default = worked example; editable)
Each line: load(kN) : repetitions. Edit freely to experiment. Single ÷1, Tandem ÷2, Tridem ÷3 per-axle for stress.
Construction-traffic check (green CTB)
Before the bituminous layers are laid, dumpers run on the fresh CTB at its 7‑day strength. The allowable stress is the IRC Eq. 3.6 value; the actual stress is from this engine. OK if actual < allowable.
Construction system (CTB over CTSB over subgrade; no BT yet). Default = the worked example's 160 mm CTB case.
| Name | E (MPa) | ν | h (mm) |
|---|
Saved designs
Saved locally in the saved_designs folder
(a report per design plus library.csv).