The four-member panel that went into the July 12 Metro mishap has fixed responsibility on the DMRC and contractor Gammon for the accident and recommended the reconstruction or modification of four pier caps near the Zamrudpur construction site.
In a 11-page report, the panel headed by IIT Professor A K Nagpal said there was a departure at site from the requirements of the design in the application of grout to the interface between the end plates of the steel strut and the face of the pier/pier cap to which the plates are attached.
"The drawings followed on site for construction of Pier 67 were advance copies and not authenticated by DMRC's design section. On enquiry, it was found that on occasions work commences without 'Good for Construction' signed drawings to avoid delayed construction," the report said.
It also recommended the "reconstruction of or modifications to pier caps 54, 66, 67 and 68 to a revised design configuration."
The July 12 incident at Zamrudpur where an under-construction metro bridge collapsed due to "design fault" in pier 67 killed seven people.
The panel also asked the DMRC to strengthen its design review system to ensure that rigorous checking of special structures is carried out in future and that certified drawings are made a prerequisite for construction to proceed.