A hoarding that collapsed in Mumbai last month claiming 17 lives was installed on a weak foundation, as per a report submitted by a technological institute to police, officials said on Thursday.

While ideally any hoarding structure in the city should be able to withstand wind speeds of 158 kilometres per hour, the billboard that collapsed in Ghatkopar could withstand a wind speed of only 49 kmph, according to the report submitted on Wednesday.

On the day of the incident, the wind speed was 87 kmph, an official said.

As many as 17 persons died and 74 others were injured after the illegal hoarding, measuring 120 feet x 120 feet in size, crashed onto a nearby petrol pump during a dust storm and unseasonal rains here on May 13, as per officials.

After the tragedy, the Brihamumbai Municipal Corporation (BMC) asked the Veermata Jijabai Technological Institute (VJTI) to find out reasons behind the hoarding crash.

The institute on Wednesday submitted the report to the Mumbai crime branch, which is probing the hoarding collapse incident, a senior police official said.

"The hoarding was installed on an inadequate and a weak foundation," the official said citing the report.

Technical experts of of VJTI had collected samples of the foundation and piling of the structure after the incident, he said.

"Considering the withstand capability of the hoarding, it establishes that it was deliberate negligence on part of the persons concerned (accused) and not an act of God," the official told PTI.

Bhavesh Bhinde, director of an advertising firm which had installed the hoarding, was arrested after the incident.

The accused had opposed his arrest saying the high velocity of the wind that led to the hoarding collapse was an "act of God" and was not in his control.

A Special Investigation Team (SIT), probing the hoarding collapse, had arrested Bhinde and structural engineer Manoj Sanghu, empanelled by the BMC, who had given a stability certificate to the hoarding.

A former director of the advertising firm, Janhavi Marathe, is also an accused in the case and search for her is still underway, the official said.

A Mumbai court on May 31 rejected Marathe's anticipatory bail plea.

While Marathe claimed she was “merely a signing authority” in the hoarding contract, police told the court she had “direct and active” involvement in the construction of the collapsed structure.

Engineer Sunil Dalvi, who had been posted in the BMC's N-ward (in which the incident area falls), has also been questioned by the crime branch's SIT in connection with the incident, the official said.

He was in-charge of the civic body's hoarding department and it was his duty to take action against illegal hoardings, he said.

He had issued a notice to Government Railway Police (GRP) for installing the illegal hoarding in Ghatkopar, but withdrew it later, the official said, adding the same billboard collapsed on May 13.

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