How the numbers are made
Methodology
What is counted
Each record is one crash reported to Police and coded in the Crash Analysis System (CAS). Counts on this site are numbers of crashes, except where a page says “people killed” or “people seriously injured”, which add up the casualty counts recorded with each crash.
Severity
- Fatal
- At least one person died within 30 days as a result of the crash.
- Serious injury
- Most severe injury was serious (for example fractures, concussion, injuries needing hospital admission).
- Minor injury
- Most severe injury was minor (for example sprains, bruises).
- Non-injury
- No one was injured. Reporting of non-injury crashes to Police is less complete than for injury crashes.
Periods
- Latest full year: 2025. Recent five-year period: 2021–2025. Shares and comparisons use this period unless stated.
- Partial years: 2026. Recent months are incomplete: crash reports reach CAS weeks or months after the event, and severities can be updated after investigation. The latest year is partial. The publisher aims to load fatal crashes within one working day, serious and minor injury crashes within about four weeks, and non-injury crashes within up to seven months.
- 2020 and 2021: 2020 and 2021 counts are affected by COVID-19 lockdowns and travel restrictions, and NZTA has noted that some crash reporting in this period is incomplete. Compare these years with care.
Why there are no crash rates or safety rankings
The data have no traffic volumes, distances travelled or road lengths, so crash counts are not crash rates. A higher count does not mean an area or road is more dangerous: busier and larger places record more crashes. Places with more people, more traffic or longer roads usually record more crashes. Shares (for example “x% of crashes were on wet roads”) describe the mix of crashes within one area and period; they are not the chance of a crash. This site does not say that any road, intersection or area is safe or dangerous.
Vehicles involved
CAS records how many vehicles or people of each type were involved in a crash. “Crashes involving” counts each crash once for each type present, so the shares add up to more than 100%.
Locations and maps
Locations are the coordinates recorded for each crash and can be approximate. Road names are as recorded in CAS. Maps are drawn from the crash coordinates only (no map tiles or third-party map services). Coordinates were retrieved in WGS 84 and spot-checked against the original NZTM2000 (EPSG:2193) coordinates. Records with missing coordinates, coordinates outside New Zealand, or coordinates far outside the recorded area are counted but not mapped. Crashes recorded at the same point (to about 10 metres) are grouped on the interactive map.
Missing values
Values recorded as “Null”, blank or “Unknown” are shown as “Not recorded”. They are never filled in or estimated.
Privacy
Each record carries the calendar year only. Dates, times, and people involved are not published, and this site does not try to identify them. Individual crash views are not indexed by search engines.