How to draw a traffic accident diagram, step by step
Published: 2026-08-07
A traffic accident diagram is a bird's-eye drawing of a collision: the road, the vehicles, where each one was going and where they met. You do not need drafting skills to make a good one — you need the right order of steps. This is the order that keeps the diagram readable.
1. Start with the road, not the vehicles
A common beginner mistake is placing the cars first and squeezing a road around them. Do the opposite: lay down the road geometry first — the intersection, curve or parking aisle — because everything else takes its meaning from the roadway.
In My Traffic Sketch you can pick from 23 road templates, draw your own roads with the road tool, or paste an aerial photo of the actual location and trace over it. If the real location is unusual, the photo route is fastest and most accurate.
2. Place the vehicles at the moment of impact
Position each vehicle where it was when the collision happened, not where it ended up. If the rest positions also matter (they often do), draw them as a second set of outlines or note them in the narrative.
Rotate each vehicle to its true angle. A car turning left mid-intersection at 45 degrees tells a completely different story than one drawn square in its lane.
3. Add directions, the impact point and context
Give every vehicle a travel arrow, mark the point of impact explicitly, and add only the context that played a role: the stop sign one driver missed, the parked truck that blocked the view, the crosswalk. Leave out decoration — every extra element costs the reader attention.
4. Identify, measure, annotate
Label vehicles V1 and V2 and record the license plates — a diagram where nobody can tell which car is which is a drawing, not documentation. Add the measurements that matter: skid length, distance from a reference point, lane width. Mark north so the reader can orient the scene.
Finish with a short written narrative. A picture plus three sentences beats either one alone.
5. Export and keep a copy
Export the diagram as a PDF. My Traffic Sketch adds a header with the case data, a table of vehicles with plates and descriptions, your narrative and a legend, so the single page reads as a complete report. Remember the diagram is illustrative: verify measurements independently before official use.
Ready to draw your own diagram? The editor is free and needs no account.
Open the free sketch tool