Seven common mistakes in traffic accident diagrams
Published: 2026-08-07
Unclear diagrams tend to fail in the same few ways. If you avoid these seven mistakes, your diagram will be clearer and far more useful to whoever reads it.
1. No direction arrows
Two cars touching, no arrows: a frequent omission, and it hides how the collision unfolded. Every vehicle gets an arrow, every time.
2. Vehicles drawn where they ended up, presented as impact positions
Rest positions and impact positions are different facts. Pick one convention, label it, and note the other in the narrative if it matters.
3. Anonymous vehicles
Rectangles with no labels, plates or descriptions force the reader to cross-reference the text for every glance at the picture. Number the vehicles and record the plates.
4. Invented precision
Writing '23.4 ft' when you paced it off is worse than writing 'approx. 25 ft'. False precision is the fastest way to lose a reader's trust — and diagram measurements are illustrative until verified regardless.
5. No north, no scale
Without a compass the words 'northbound' in the narrative cannot be matched to the picture; without a scale reference, distances are guesses. Both take seconds to add.
6. Clutter
Every parked car on the street, every tree, every building — irrelevant elements bury the relevant ones. If it did not influence the collision, it does not belong.
7. The diagram and the narrative disagree
The text says V1 turned left; the drawing shows it going straight. Contradictions between picture and words are what opposing parties look for. Draw first, then write the narrative while looking at the diagram — or use a tool that exports them on the same page so the mismatch is easy to catch.
Ready to draw your own diagram? The editor is free and needs no account.
Open the free sketch tool