Thiruvananthapuram: A water pipeline burst caused the road cavity on the Thuravoor–Paravoor Project stretch of NH-66 on Tuesday, the National Highways Authority of India (NHAI) stated in a release issued here on Wednesday. The crater was spotted on Tuesday evening. 

"Based on the preliminary technical assessment, the cavity is suspected to have been developed due to the bursting of an underground Glass Fibre Reinforced (GFR) water pipeline last week, which is believed to have caused progressive erosion of the underlying soil beneath the pavement," the NHAI release stated.

Immediately after the incident, an inspection was carried out by officials of NHAI along with representatives of the PWD and the Kerala Water Authority. It has been reported that the EPC contractor had already laid a new Ductile Iron (DI) water pipeline parallel to the affected stretch. However, the new pipeline has yet to be commissioned and connected to the active distribution network. 

Consequently, the existing GFR pipeline continued to remain in service. The reported failure of this pipeline is considered to have contributed to the erosion of the supporting soil beneath the highway, resulting in the formation of the cavity.

The reasons for the delay in commissioning the newly laid pipeline and the consequent non-decommissioning of the existing pipeline are being examined as part of the ongoing investigation.

Immediately upon detecting the cavity, the affected section of the highway was barricaded and secured to prevent any accidents. The maintenance team promptly carried out preliminary repair works and comprehensive restoration work is also completed. The entire rectification work is being carried out at the risk and cost of the Contractor, the NHAI release noted.