Culvert Designer — semi-automated sizing, inlet & outlet co

What is Culvert Designer?

Culvert hydraulics with inlet and outlet control checks, headwater–discharge performance curves, and multi-barrel configurations — plus a sizing assistant that ranks commercial barrel sizes against your headwater, velocity and cover constraints.

When would you use this?

Sizing a road or river crossing where headwater, outlet velocity and cover all have to be satisfied at once.
Checking a culvert someone else specified, against both inlet and outlet control.
Comparing barrel counts, materials and inlet details before committing to a detail.

How Delta Hydro Studio handles it

Ask "what barrel should I use?" and get a ranked table of commercial sections, not just a pass or fail on one guess.
Every candidate is run through the same HDS-5 analysis the tool uses when you analyse by hand — no shortcut model behind the recommendation.
Near misses stay on the table with the failing constraint named, so you can see what a limit is costing you.
The sizing study carries into the Word and Excel report, so a semi-automated design is still reviewable.

How to use it

1
Open the Culvert Designer and enter the crossing — discharge, tailwater, roadway and inverts.
2
Press "Size it for me" and set your constraints: HW/D, outlet velocity, cover, freeboard.
3
Review the ranked candidates, expand any row to see every check and margin.
4
Adopt one into the form, adjust anything you like, then analyse and export.

Methodology & references

Full equations, assumptions, and literature references appear inside the in-app methodology panels for this tool, aligned with South African guidance (SANRAL TRH, SANCOLD, DWS technical manuals) and international references (USDA NRCS, FHWA HDS) where applicable.

Outputs & exports

Export professional Word and Excel report packs, tabulated results, and GIS-friendly layers depending on the tool. Screenshots in marketing materials are refreshed as the UI evolves — the studio always reflects the latest layout.

Ready to run Culvert Designer?

Free tier available — no credit card required to explore.

Launch in Studio Book a demo

FAQ

Does the sizing assistant choose the culvert for me? +

No. It returns a ranked list of commercial sections that satisfy the constraints you set, and nothing changes in your design until you pick one. Constructability, standard details and what the road authority will accept are not in the model — that is your call.

Where do the candidate sizes come from? +

A catalogue of nominal commercial sections, scoped to your region, so a recommendation is something you can order. Metric series apply worldwide; US-customary series apply in the United States. Every candidate names the catalogue it came from.

What happens when nothing works? +

The assistant names the constraint that failed on the most candidates and tells you how close the nearest miss came — for example, that every option exceeds the headwater limit and the closest misses by 180 mm. That tells you which limit to revisit.

Do I need a desktop GIS install to use Culvert Designer? +

No. Delta Hydro Studio runs in the browser — upload inputs, run calculations, and export professional outputs without local GIS installs for most workflows.

Is there a free tier? +

You can start free on the Stream plan with credits to explore tools. Several hydraulic and delineation tools remain accessible without a paid subscription.

Where are my data and calculations stored? +

Projects live in your Delta Hydro Studio workspace. Export Word, Excel, and GIS formats when you need offline archives or submittals.