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Drainage Arrows + Flow Paths

The drainage arrows drafters place by eye, computed from the surface.

Command VDCDRAINARROW · VDC Civil tab › Grading panel
The drainage arrows drafters place by eye, computed from the surface.

What it does

  • Grid mode carpets an area at your spacing; pick mode places arrows exactly where you click.
  • Each arrow aligns to the surface's downhill direction at its point; optional slope-percentage text.
  • Arrow blocks or plain arrows, size and layer in the dialog.

Worth knowing

  • Arrows are static linework: re-run after a regrade.
  • Flat cells are skipped and counted, never guessed.
  • Settings: %APPDATA%\VDC\DrainArrow\ (env VDC_DRAINARROW_SETTINGS).

Dialog

Drainage Arrows + Flow Paths dialog
Drainage Arrows + Flow Paths, VDCDRAINARROW

When to use it

  • Grading plan annotation - arrows that actually agree with the proposed surface.
  • QC-ing a lot or road for the drainage pattern the surface really drains.

How to run it

  1. Run VDCDRAINARROW, pick the surface and arrow style/size.
  2. Choose grid mode (set the spacing) or pick points one after another.
  3. Review - arrows point downhill from each sample; slope text optional.

Options

  • Grid or picked: carpet an area at a spacing, or click exactly where arrows belong.
  • Slope text: optional percentage label on each arrow.

Watch out for

  • Arrows are static linework - re-run after a regrade (they don't follow the surface).
  • Flat cells (no meaningful slope) are skipped and counted, not guessed.

Related: Auto-Grade Lots · Smooth Surface · Pond QC (Geometry)