The collapse of concrete lumps from the Lalbaug flyover at Saint Jagnade square on Friday night has once again led to a scrutiny of its construction flaws. This is the second such incident on the 2.4-km flyover.
On April 12, 2012, lumps of concrete fell at Lalbaug junction. However, the quality of construction had become questionable much earlier, when potholes surfaced days after inauguration of the flyover in June 2011.
Transport experts said concrete lumps fall off expansion joints due to use of sub-standard construction material. An expansion joint lies between two segments to safely absorb the heat-induced expansion and contraction of construction materials.
Transport expert Jitendra Gupta said: “The material used to fill expansion joints must be flexible so as to sustain expansion and contraction of segments. It seems an inferior plastic component has been used here.”
Sudhir Badami, another transport expert, said: “The expansion joint has to be filled with compressible material like thermocoal, rubber. Concrete may get crushed when it is compressed and lumps of its may fall off.”
The Mumbai Metropolitan Region Development Authority (MMRDA) sought to play down the incident, blaming the contractor of the flyover, Simplex Infrastructures Ltd. PRK Murthy, chief of the transport and communication department of MMRDA, said: “It is not a major issue. Just small lumps of concrete have fallen. Such a problem occurs when work on expansion joints is not done properly. The structure as a whole is safe.”
“We have asked the contractor to remove all loose concrete lumps from expansion joints under the defect liability clause. We have also fined the contractor Rs25 lakh for the past incident,” said Murthy.
A statement from Simplex read : “Modifications are currently being carried out on the flyover on instructions of MMRDA and under their supervision.”