Road design Calculator
🛣️
Road Design Calculator
Civil Engineering · Geometric Design · Pavement · Earthworks
v2.0 · ZMW/SI
Geometric Design
Horizontal & Vertical Alignment · Cross-Section · Sight Distance
Road Classification & Design Speed
🚗 Basic Parameters REQUIRED
km/h
km
Horizontal Alignment
↩️ Horizontal Curve Design
deg
%
coeff
Vertical Alignment
📈 Vertical Curve & Grade
%
%
m
m
Cross-Section
🛤️ Cross-Section Elements
lanes
m
m
%
Cross-Section Diagram
📊 Design Parameters Summary
| Parameter | Calculated | Minimum Required | Status |
|---|
Pavement Design
CBR Method · Structural Number · Layer Thickness
Traffic & Loading
🚛 Traffic Loading
veh/d
%
years
%
ESA
Subgrade & Materials
🏔️ Subgrade & Layer Properties
%
📊 Layer Design Summary
| Layer | Material | Thickness (mm) | a-coefficient | SN Contribution |
|---|
Earthworks & Quantities
Cut · Fill · Haul · Mass Haul Analysis
Section Geometry
⛰️ Cut / Fill Parameters
m
m
m
m
H:1V
H:1V
Material Properties
🪨 Soil & Material Factors
ratio
m
📊 Mass Haul Summary
| Description | Bank m³ | Loose m³ | Compacted m³ |
|---|
Drainage Design
Rational Method · Culvert Sizing · Side Ditch · Manning’s Equation
Catchment & Rainfall
💧 Hydrology Inputs
ha
mm/hr
0–1
years
%
Manning’s Roughness
📐 Channel Properties
n
m
H:1V
m
📊 Hydraulic Summary
| Parameter | Value | Unit | Note |
|---|
Cost Estimate
Bill of Quantities · Unit Rate Analysis · ZMW
Project Parameters
💰 Project Inputs
km
m
%
%
📋 Bill of Quantities
| Item | Unit | Qty | Rate (ZMW) | Amount (ZMW) |
|---|
Design Reference
Standards · Minimum Values · Typical Ranges
Design Speed vs. Geometric Standards
🚗 Geometric Design Standards
| Parameter | 80 km/h | 100 km/h | 120 km/h | Note |
|---|---|---|---|---|
| Min. Horizontal Radius | 230 m | 395 m | 600 m | e=8%, f=0.14 |
| Min. Stopping Sight Distance | 130 m | 185 m | 255 m | AASHTO 2018 |
| Min. K-value (Crest) | 26 | 52 | 95 | SSD basis |
| Min. K-value (Sag) | 23 | 37 | 55 | Comfort |
| Max. Grade (Rolling) | 6% | 5% | 4% | Per terrain |
| Lane Width | 3.5 m | 3.65 m | 3.65 m | Minimum |
CBR-Based Pavement Thickness Guide
🏗️ Pavement Layer Guide
| CBR (%) | Wearing Course | Base | Subbase | Traffic Level |
|---|---|---|---|---|
| ≤ 3 | 50 mm | 200 mm | 300 mm | Light |
| 3–7 | 50 mm | 150 mm | 200 mm | Medium |
| 7–15 | 40 mm | 125 mm | 150 mm | Medium |
| > 15 | 40 mm | 100 mm | — | Any |
💧 Manning’s n Values
| Channel Type | n |
|---|---|
| Concrete pipe/lined | 0.012–0.015 |
| Dressed masonry | 0.015–0.018 |
| Earth, clean | 0.022–0.026 |
| Earth, gravelly | 0.025–0.030 |
| Rock cut | 0.030–0.040 |
| Dense vegetation | 0.035–0.050 |
🏃 Runoff Coefficients (C)
| Surface Type | C |
|---|---|
| Steep rocky slopes | 0.70–0.90 |
| Cultivated fields | 0.30–0.50 |
| Bush / savanna | 0.20–0.45 |
| Dense forest | 0.10–0.25 |
| Road surface | 0.70–0.90 |
| Mixed catchment | 0.40–0.65 |
Zambia-Specific Notes
🇿🇲 Zambia Road Agency Standards
- ▸Road network classified under RDSA/RDA standards: Trunk, Main, District, Urban, and Community roads.
- ▸Design speeds: Trunk 100–120 km/h · Main 80–100 km/h · District 60–80 km/h · Community 40–60 km/h.
- ▸Rainfall: Zambia receives 600–1,400 mm/year. Use IDF curves from ZMD for hydraulic design — peak intensity typically 50–120 mm/hr for 1-hour, 25-year return period.
- ▸Subgrade CBR < 3% requires lime or cement stabilisation. Expansive black cotton soils common in Southern/Eastern provinces — require special treatment.
- ▸Reference standards: AASHTO 1993 Pavement Design, SATCC Geometric Design Manual, RDA Pavement Design Manual (2018).