Measure directional fetch across open project boundaries accurately. Adjust for wind angle, terrain, and obstructions. Review graphs, tables, and exports before finalizing design choices.
| Case | Length | Width | Angle | Terrain | Obstruction | Safety | Design Fetch |
|---|---|---|---|---|---|---|---|
| Yard A | 120 | 60 | 30° | 1.10 | 0.90 | 1.15 | 155.17 |
| Pad B | 90 | 40 | 20° | 1.05 | 0.95 | 1.10 | 113.48 |
| Zone C | 160 | 85 | 45° | 1.20 | 0.88 | 1.20 | 220.42 |
This calculator uses a directional projection method for a rectangular project area. First, it resolves site length and width along the incoming wind direction.
Projected Fetch = |L × cos(θ)| + |W × sin(θ)|
After that, terrain and obstruction adjustments are applied:
Adjusted Fetch = Projected Fetch × Terrain Factor × Obstruction Factor
A final design allowance is then added:
Design Fetch = Adjusted Fetch × Safety Factor
This method is useful when planners need a quick directional exposure estimate for site layout checks, temporary works review, hoarding placement, and wind-sensitive construction planning.
Fetch length is often used as a practical exposure indicator. A longer directional fetch may suggest stronger uninterrupted wind action across access roads, laydown areas, open slabs, scaffolds, temporary barriers, and material storage zones. It does not replace a formal wind engineering study, but it helps compare layouts quickly during planning and review.
Designers can test several wind angles and obstruction assumptions to see which arrangement reduces exposure. This is useful when deciding fence lines, screen walls, temporary stacking areas, or sheltered equipment positions. Because the model is transparent, teams can explain each assumption and document the basis clearly in early coordination meetings.
Fetch length is the uninterrupted distance wind travels across an exposed area before reaching a point of interest. It helps estimate directional exposure during layout planning.
Wind rarely approaches a site from only one direction. Angle changes the projected path across the rectangular site, so the effective fetch can rise or fall significantly.
Terrain factor reflects the openness of the surrounding area. Open surroundings usually increase exposure, while rougher terrain may reduce the effective wind reach.
Obstruction factor accounts for nearby barriers, structures, vegetation, or stored materials that interrupt the wind path. Lower values usually reduce the adjusted fetch length.
No. This tool is best for screening, comparison, and planning. Final structural design should follow project codes, wind studies, and engineer-reviewed assumptions.
Yes. Select feet in the unit field. Keep all dimensional inputs in the same unit so the result remains consistent and easy to interpret.
The fetch ratio compares design fetch to site diagonal length. It is a simple indicator that helps classify the relative exposure level of the site.
Exports help teams document assumptions, attach summaries to reviews, and share consistent results with planners, supervisors, clients, and temporary works reviewers.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.