Engineers urge govt to probe flaws in metro edifice

The Bangalore Metro Rail Corporation Limited (BMRCL) is hiding a major structural issue in building the metros which the government must probe urgently, say structural engineers.

Though honeycombing is a common factor in the concrete structure, engineers and contractors should take good care of it during the laying stage. Gaps found when removing the mould should have been corrected immediately, he explained, so it is likely that errors happened at the execution stage.

Pointing to the flaws, a structural engineer working closely with the government, who asked not to be named, said longevity and lifespan of the metro structures have not been tested properly.

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“When BMRCL admits similar errors have happened before, it only shows their negligence. Non-destructive ultrasound test should’ve been conducted back then,” he said.

“Concrete structures develop honeycombs while pouring cement in the gaps in the steel pillars. It only shows that the work has been carried out in haste at the first step. It’s poor workmanship. It also raises questions about the quality of the concrete.”

Founder and CEO of Prasad Consultants H N R Prasad said structural design and tests on supporting pillar and cantilever beam should be checked thoroughly.

Chandra Kishen J M, Professor at Structural Engineering Laboratory, Department of Civil Engineering said honeycombing happens when concrete is poured and not vibrated properly.

There are quality assurance teams at every level (including at contractor and BMRCL level) who should have checked it, he said.

Kishen, a consultant for Metro- Phase-2 works, said honeycombing do not pose an immediate threat to the structure since it happens outside. But over the years, water and atmospheric salt seeps in and corrodes the structure.

During his stint as a consultant, Kishan said a lot of honeycombs were found in the pillars of phase 2. The BMRCL was informed and remedial action was taken swiftly.