Draw a collision diagram that answers the question everyone asks: how did this happen?
A collision diagram is the top-down drawing that turns a paragraph of description into something a reader understands in seconds — where each vehicle was, where it was heading, and where the two met. This tool draws one in your browser, free, and exports it as a PDF or PNG you can attach to a claim or a report.
Draw a collision diagramWhat belongs in a collision diagram
Whether it is drawn by an officer at the scene or by a driver the same evening, a collision diagram carries the same core elements:
- ▸The roadway — the intersection, curve, highway or parking lot where it happened, drawn to a consistent scale.
- ▸Each vehicle in its position at the moment of impact, labelled V1 and V2 so the narrative can refer to them.
- ▸A travel arrow per vehicle showing the direction each was moving before the collision.
- ▸The point of impact, marked distinctly from the vehicles themselves.
- ▸Measurements — lane widths, distance to the stop line, skid length — in feet or meters.
- ▸A north arrow, so the reader can orient the drawing against the real road.
Collision diagram, crash diagram, accident sketch — the same drawing
The names change with who is asking. Police reports call it a crash diagram or field sketch; insurers ask for an accident diagram or a diagram of the loss; traffic engineers use collision diagram for the summary drawing that plots every crash at one location over several years. This tool draws the single-incident kind: one collision, drawn clearly enough that a stranger understands it.
If you need the engineering sense — many crashes plotted on one intersection to reveal a pattern — you can build that too by placing several incidents on the same layout, though the tool is designed for documenting one event at a time.
Draw it over the real intersection
Road templates cover the common layouts, but a specific intersection rarely matches a generic cross. Paste a satellite screenshot of the actual location and trace the roads over it — the photo dims behind your drawing, so the exported diagram shows clean lines with the real geometry underneath. Lane counts, turn pockets and odd angles come out right instead of approximated.
What the export looks like
The PDF prints the diagram with a header for the case number, date, examiner and scale, a table of the vehicles with their plates and descriptions, and your narrative underneath. It reads as a document, not a screenshot — which matters when it lands in a claim file next to paperwork from people who do this professionally.
Every export carries a line stating the diagram is illustrative and its measurements are not forensic. That is deliberate: an honest diagram is more useful than one that overstates what it proves.
How it works
- 1. Choose the road layout that matches the scene, or paste a map screenshot and trace it.
- 2. Place each vehicle, rotate it to its real angle, and label it V1 and V2.
- 3. Draw the travel arrows and mark the point of impact.
- 4. Note the scale you used and the distances you actually measured, then export.
Frequently asked questions
What is a traffic collision?
A traffic collision — also called a crash, a motor vehicle accident or an MVA — is any impact involving at least one vehicle in motion on a roadway. Documenting one usually means three things: photographs, an exchange of information, and a diagram showing how the vehicles came together.
What is a collision diagram?
A collision diagram is a top-down drawing of a traffic crash showing the roadway, the vehicles involved, their direction of travel and the point of impact. It lets a reader understand the sequence of events without reading a long description.
Is this collision diagram maker really free?
Yes. There is no account, no trial and no watermark, and the diagram never leaves your device — the drawing is stored in your own browser until you export it.
Can I use the diagram in an insurance claim?
Many claim forms ask for a diagram, and a clear one helps an adjuster understand the scene. It is illustrative rather than forensic — the export says so — so treat it as documentation of what you observed, not as a reconstruction.
What scale should a collision diagram use?
Pick a grid value you can measure against — the tool lets you set feet or meters per grid square — and keep it consistent across the drawing. Stating the scale on the diagram matters more than the exact number you choose.