The team of experts probing the collapse of a portion of the VIP Road flyover more than two weeks ago has been kept waiting for the most important bits of information needed to nail the cause, sources said.
The Calcutta Metropolitan Development Authority (CMDA) has yet to submit the complete design notes of the superstructure that came crashing down along with those of the bearings, as sought by the Jadavpur University professors investigating the incident.
Design notes running into 150 pages did reach the probe team at JU last Friday, but they were allegedly of little help as the crucial bits were missing.
“The design notes on the superstructure between piers 19 and 20, which caved in, need to be studied in detail. But the hard copy that the CMDA sent last week did not contain all the relevant papers,” a source in the civil engineering department of JU said. “It seems the agency handed the probe team documents without bothering to check whether they would be of any help in the probe.”
Two days after the cave-in, urban development minister Firhad Hakim had announced that a team from IIT Kharagpur would separately study the drawing and design of the flyover. But nothing has progressed on that front.
IIT Kharagpur said on Thursday that it hadn’t received any formal letter seeking to involve its experts in the investigation.
Sankar Kumar Som, the acting IIT director, said: “We have not received any letter of request from the state government. Generally, such requests are sent to the director, who forwards it to the appropriate department. Even if the government sent it directly to the civil department, they would have informed me.”
The head of IIT Kharagpur’s civil engineering department, Subhasish Dey, hasn’t received any communiqué either. “I was at the institute till Wednesday and did not get any letter. Had there been any such letter today, I would have received a call from my department,” Dey told Metro over the phone from Surat.
A study of the complete design notes is crucial to understanding the stability of the structure and ascertaining any fault, according to a teacher of the civil engineering department at Bengal Engineering and Science University (Besu). “It is obvious that there was some critical fault at some stage of construction. This might be in the design calculation of the superstructure coming up on the sharp curve. For this, it is extremely crucial to study the complete design notes. I don’t know why the CMDA is yet to hand over all the documents,” the teacher said.
A professor in the construction engineering department of JU stressed the need to study the design notes of the bearings as well. “A fault in the use of bearings may have had some role in the collapse. So, it is important that the investigation team is provided the design notes of the bearings at the earliest,” he said.
The CMDA said it had no problem with sharing any document with the probe team, putting the onus on the experts to state in writing what they were looking for. “Let them give us in writing. We will give them everything,” an engineer said.
The engineer also suggested that the probe team was dragging its feet, not the CMDA. “After getting the papers, the team was supposed to visit the spot to check the quality of the existing structure. But they are yet to do so.”
A source said JU professors Dipankar Chakravorty and Arup Guha Niyogi had planned to use a gadget to send “ultrasound pulse” through the concrete deck slab to ascertain its stability. The search for an agency to run the specialised test is underway, he added.
A structural engineer not associated with the probe questioned whether the authorities were serious about nailing the cause of the crash, given their reluctance to hand over all the relevant documents. “Handing over the relevant papers is a basic requisite. It is also important that efforts are made to salvage the submerged portion of the bridge, which could hold crucial pieces of evidence.”
Chakravorty, who is heading the probe, said: “We are studying the papers that have been given to us so far. If we need something, we can always write to the CMDA. The agency is co-operating with us.”
Colleague Niyogi declined to comment.