Kolkata flyover collapse was due to flaw in its design, the experts said, after visiting the spot, denying the construction company’s argument, that it was an “act of god”.

Several experienced structural and civil engineers said that, the structural flaw of a T-shaped pillar, technically a cantilever pier, led to the collapse. A cantilever bridge rests on structures that project horizontally into space, only on one end.

On Thursday, a portion of flyover was caved, killing 24 people and injuring about 90. Few hours later, the concerned builder said that, Kolkata flyover collapse was an act of god.

“The design of the pier head (the t-junction) was inadequate. The arms simply buckled under pressure of the steel and concrete,” said Achyut Ghosh, a bridge expert and visiting professor at IIT Kharagpur, Jadavpur University and IIEST in Shibpur.

“The bridge was yet to be inaugurated, and therefore, there were no pressure of vehicles that a functioning flyover carries. This proves that it was simply a design failure. This was preventable. It can’t be called an accident,” he added.

Speaking about the cantilever piers, the experts said that, they are the most unstable structures and are usually avoided. If at all, there comes a requirement to use them for sure, then they are meticulously designed and need perfect implementation with strict quality check of materials.

“It appears to be a technical failure. What was running on two pillars (at the start of the bridge) has converged on to one pillar. But this single pillar did not have adequate strength,” said professor Arun Chakravarti of IIEST, Shibpur.

Snehasis Sinha, an experienced civil engineer, who visited the spot earlier said that, there could have been serious lapses in quality control and also execution.

“Apart from the flawed design there could be compromise in quality of materials and even lapses on the implementing authority’s part while the flyover was being built. There could have been lapses in monitoring and checking,” he said.

By Phani Ch