18-05-2025
Workers race against the clock to fix OMR cave-in
Chennai: Motorists taking
Old Mahabalipuram Road
(OMR) near Thiruvanmiyur junction on Monday morning may face traffic delays, as workers race overnight to complete repairs on a massive cave-in that disrupted the arterial corridor on Saturday night.
Though the barricaded portion may be narrowed to 4–5m by the morning, movement through this stretch, which connects Thiruvanmiyur with Taramani, will be affected.
Over the weekend, Tamil Nadu Road Development Corporation (TNRDC) and Metrowater engineers worked 36 straight hours to contain the damage after a car fell into a six-foot-deep crater on Saturday, injuring five passengers. The vehicle was lifted out around 9pm, after which officials began excavation and diagnostics.
The cave-in was traced to the sudden failure of a 2.2m-diameter prestressed cement concrete (PSC) sewage pipeline laid nearly two decades ago. Unlike modern ductile iron or High-Density Polyethylene (HDPE) pipes, PSC pipes rely on a tensioned steel framework embedded in concrete, and their brittle nature makes them prone to sudden breaks under stress or age-related wear.
In this case, the failure occurred at a weak joint located roughly three metres below road level — deeper than previous minor bursts reported at Kasturba Nagar and Indira Nagar.
Engineers first had to safely access the sewer chamber, ventilating it to mitigate the risk of poisonous gas exposure before clearing out a sludge-heavy sewage-mud mix with earthmovers. "On Sunday afternoon, they began installing reinforcement sheets over the damaged portion. However, sourcing compatible materials proved difficult, as PSC pipes are no longer manufactured widely and prefabricated sheets of the same grade are not readily available," said a senior highway engineer.
By Sunday night, the team planned to grout concrete-mix into the void to stabilize the road base. This would allow partial reopening for Monday. But full relaying of the road will be deferred by at least two days, pending leak monitoring and structural settlement checks. If stable, final relaying is expected to begin by Tuesday.
