Kolkata: Expert opinion will be sought in regard to the causes of the collapse of the Majerhat bridge, Joint Commissioner of Police (Crime) Praveen Tripathi informed on Thursday.He also said the Public Works Department (PWD) had given a No Objection Certificate (NOC) to the Rail Vikas Nigam Limited (RVNL).According to sources, Kolkata Police had formed a Special InvestigationTeam (SIT) two days after the bridge caved-in. Later the SIT asked the Metro authority and PWD to submit all the relevant documents they had regarding the same. Also Read – Rain batters Kolkata, cripples normal lifeOn Thursday, Tripathi informed that the PWD authority was asked to provide all documents related to the maintenance work, construction and other necessary papers in this regard which they have complied with.As per the list, copy of a NOC is also there that was given to the RVNL. He also informed that the Metro authority also submitted certain documents. More will be provided soon by them. “We will now sort the documents and scrutiny all of them thoroughly,” said Tripathi.The SIT will also engage an expert agency for opinion. According to police, they may engage the Indian Institute of Technology (IIT) Kharagpur or IIT Roorkee for the same. Their main objective is to gather information about the structural engineering part which may provide assistance to detect the cause of the collapse of the Majerhat bridge.