Municipal pipelines such as water supply and drainage, electricity, gas and communication are buried under urban roads which are affected by vehicle load, vibration, groundwater level and other factors. Disasters such as pavement collapse and cracking, are easily caused which result in inconvenience to urban production and life and may even cause personal injury. This is particularly the case in recent years, with the further expansion of the urban scale and the increasing density of underground pipe network in some cities. Geological disasters of urban roads are occurring frequently, which has attracted the increased attention of the municipal departments and the general public.

 

Similarly, the application of robot technology in the inspection of internal defects of urban sewer and non-excavation pipeline repair technology has attracted wide attention because of the advantages of high repair efficiency and low repair cost.

 

After a period of service, the materials used in urban roads and urban sewers gradually age and their functions decline potentially resulting in geological disasters and potential safety hazards. In order to find the potential safety hazards and take measures to eliminate them, it is necessary to regularly evaluate the risk of urban road underground failures and the internal defects of urban sewer. Since accreditation is an affirmation of the management and technical competence of the inspection body, there is an increasing demand for accreditation in the competence of risk evaluation in underground failures related to urban roads and the competence in internal defect evaluation of urban sewers.

 

CNAS has actively responded to the accreditation needs in the above fields organizing experts to study and discuss the characteristics and technical requirements of inspection and testing activities in these two fields, and promote accreditation of the inspection bodies. Following analysis, the inspection items for urban roads is the detection and evaluation of attributable characteristics of underground failures such as cavities underneath the pavement, voids, loosely infilled voids, water-rich voids in the area using detection methods such as ground penetrating radar method for urban roads according to relevant technical standards, and to carry out a risk evaluation. The inspection items for urban sewers are sewer defects and condition evaluation, including the detection of structural and functional defects of urban sewers using closed circuit television inspection and quick view pipe inspection methods using the relevant technical standards Then to evaluate and judge the structural and functional conditions of the sewer and calculate the rehabilitation index and maintenance index. These two types of activities include the typical characteristics of inspection activities. Therefore, inspection accreditation in accordance with ISO/IEC 17020 is applicable.

 

CNAS is accrediting inspection bodies in these two technical fields. Competence in the detection and evaluation of underground failures in urban roads and sewer defect and condition evaluation of urban sewers is accredited according to the inspection body accreditation standard ISO/IEC 17020. As of August 2023, in the above fields, a total of 31 inspection bodies have been accredited by CNAS, with more inspection bodies currently in the process of seeking accreditation for these activities.