The May 3 collapse of an elevated section of the Line 12 subway in Mexico City that killed 26 passengers appears to have resulted from multiple construction faults, according to a risk management firm's preliminary report.
The findings, released June 16 by Norwegian firm DNV, identify faults such as deficient welding of metal studs connecting the structure’s steel beams with a precast concrete track bed. Stud placement was inconsistent as well, the report says, with some attached with the removable ceramic rings still in place.