Gurgaon: A portion of Sohna highway caved in again on Monday, leaving a three-foot-wide sinkhole. This comes barely two months after National Highways Authority of India (NHAI) completed repair work. This is the eighth time since 2023 that sinkholes have appeared along the same stretch. The cave-ins are linked to a damaged 1,800 mm master sewer line beneath the highway.With sewer water flowing out continuously, the damage is likely to widen further. This has prompted NHAI to cordon off the damaged portion and close one lane while regulating traffic around the site. The new cave-in is about 30metres away from the spot where a similar collapse occurred in May this year. That one created a 10-foot-wide sinkhole and the highway was restored only in Sept.Multiple sinkholes have exposed the fragility of the sewer infrastructure. Incidents were reported in Dec 2023, July 2024 and May 2025, including a 12-foot-deep pit near Sispal Vihar caused by a collapsed sewer line and chamber. On June 30 last year, another sinkhole, about two metres wide and six metres deep, appeared on the same stretch. A smaller cave-in on June 18 also forced authorities to shut nearly one-and-a-half lanes as a precaution. In May this year, a 10-foot-wide sinkhole appeared. Before the road could even be restored, another portion of the stretch caved in during Aug.An NHAI official said the area is being barricaded and that permanent restoration works will be taken up this time, using cured-in-place pipe (CIPP) technology. “We will take up permanent restoration works this time with CIPP. The work has been awarded and desilting and diversion of flow will be completed in Nov. The CIPP work will begin in Dec and we expect the project to be finished by Feb end,” the senior NHAI official said.The permanent fix has two components. First, about 2,700 metres of the existing pipeline between Tau Devi Lal Stadium and Sispal Vihar will be rehabilitated using cured-in-place pipe (CIPP) technology, which relines the damaged sewer from the inside without the need to dig up the road along its full length. Second, about 100 metres of the sewer pipeline that currently runs beneath the main carriageway will be shifted to the service road through a new pipe, taking the line out from under the highway’s main traffic stream. Traffic will be diverted for a short duration while the new pipe is laid, the official said. The entire project is estimated to cost Rs 58 crore.Rehabilitation of the line with CIPP was first proposed in 2017 by Haryana Urban Development Authority (HUDA), now Haryana Shehri Vikas Pradhikaran, at an estimated Rs 28.7 crore. The plan also included laying a 900 mm line from Subhash Chowk towards Sector 48 and strengthening manholes. NHAI was to execute the work under HUDA’s supervision. During road widening and the administrative transition from HUDA to GMDA, however, the project was scaled down to manhole strengthening alone, which NHAI says it completed. The main pipeline was left unaddressed. After prolonged blame-shifting between agencies, it was decided last year that NHAI would undertake the full rehabilitation using CIPP.
