1.4.4 Verification of cracking measurement
These guidelines cover both manual and automated cracking surveys.
- Verification testing is based on fresh surveys of a length of road with known cracking characteristics. The aim is to confirm that the measuring system has not changed. However, it must be noted that due to temperature and other effects it cannot be expected that a reference section can be maintained where cracking will be constant over time. It is therefore necessary to concentrate on repeatability and to keep some record of observed cracking, also with recording of environmental conditions, particularly temperature.
- Verification sections should be located where crack types and cracking levels (severity and extent) are known. These sections should be 500 m in length and surveyed on a regular basis, at least six‑monthly, and if specifically required, at the commencement of large scale data collection surveys.
- Detailed verification testing is necessary to assess a new system before it is commissioned for use in cracking surveys.
- For automated crack surveying equipment, after a thorough and successful initial calibration and verification has been undertaken, further verification is required:
- after changes to hardware and software; and
- at the beginning of a network survey; or
- at intervals not exceeding six months; or
- at intervals not exceeding 3000 kilometres of survey (whichever of these three comes first); and
- at the end of a network survey.