Kasaragod: The Periya underpass, which was under construction, collapsed because the joints of the staging pipes could not withstand the weight of the wet concrete, said a report by experts from the National Institute of Technology (NIT), Karnataka.
The staging pipes were connected by inserting thinner pipes between them, said the report submitted to the National Highways Authority of India (NHAI). "The failure of the joints (of the pipes) to cater to the load, and the cascading effect led to the collapse of the stage," it said.
Thirteen workers had a narrow escape when the 6-metre-high stage - being built by Hyderabad-based Megha Engineering & Infrastructures Limited (MEIL) - collapsed at 3.23 am on October 29.
The workers were atop the stage pouring in pumpable concrete to make the girders. The supporting stage first slumped and after an 18-second pause came crashing down. The workers used that 18-second window to run and take refuge on top of the two abutment walls, 16.6m apart. One worker was injured in the accident.
The five experts from the Department of Civil Engineering of NIT-K, Surathkal, recommended that MEIL should not avoid using such joints till an exercise was conducted to test their resilience. The NIT-K team was led by prof K S Babu Narayan, whose area of interest includes structural analysis and design.
One of the team members from the same department said the staging pipes "appeared" rusted. MEIL officials told the experts that the pipes were only one-and-half years old and they usually had a life of 15 years. "We could not access the internal strength of the pipes so the report avoided commenting on them," said the expert.
The report was submitted to the regional officer of NHAI in Thiruvananthapuram. Calls made to the office went unanswered.
