Overview
ISO 3784:1976 specifies requirements for the measurement of impact velocity in road-vehicle collision tests. The standard defines the required measurement accuracy and the timing of the measurement relative to impact, and it describes typical methods in an annex to facilitate comparison of results between laboratories. Other methods may be used provided they meet the core requirements.
Key parameters specified in the standard:
- Accuracy: measurement accuracy is specified at 1% (as required by the standard).
- Timing: the impact velocity measurement shall be made within 0.2 s prior to impact, ensuring the recorded speed is representative of collision conditions.
Key Topics
The annex outlines three general measurement categories and specific techniques commonly adopted by test laboratories:
Practical considerations emphasized in the standard include calibration, rigid sensor mounting (to avoid geometric errors), minimization of parallax for optical systems, and ensuring no tyre slip for wheel-based methods.
Applications
- Regulatory and research crash testing for road vehicles.
- Inter-laboratory comparison of collision test data.
- Validation of vehicle safety systems that depend on pre-impact speed measurements.
Related Standards
- ISO 3784 is part of the road-vehicle testing domain maintained by ISO/TC 22 (Road vehicles). Laboratories should apply ISO 3784 alongside other crash-test and instrumentation standards covering sensor calibration, data acquisition, and test procedures to ensure full traceability and comparability of impact-velocity data.
For implementation, follow the annex methods as examples and ensure any alternative technique meets the 1% accuracy and 0.2 s timing requirements set by ISO 3784:1976.
