SHANGHAI -- Shanghai authorities on Sunday said that the incident involving a crane collapsing onto a metro track was caused by improper construction management.

An official investigation concluded that the accident, which occurred on Dec 22 near an expressway section under construction, was caused by operations carried out in violation of due procedures.

A crawler crane collapsed, with its main arm falling onto the metro track, partially damaging the front of a train operating on Line 11 and triggering an emergency stop, according to the municipal government.

The incident resulted in a direct economic loss of 18.31 million yuan (about $2.54 million). No casualties were reported.

Several people, including the crane operator from the construction company, have been deemed liable for the accident.