Missing bolts contributed to Mexico City metro collapse: Report

Poor welding also contributed to Metro Line 12 collapse that killed 26 people in May, independent auditor finds.

A deadly Mexico City metro collapse in May was caused in part by missing bolts in the beams of an overpass that already had deficiencies before an important earthquake, an independent auditor’s report released on Tuesday by the city government has found. The 180-page analysis by Norwegian company DNV was the latest instalment of its technical opinion on the May 3 collapse – Mexico’s biggest train accident in years. Twenty-six people were killed when an overpass and train carriage on Metro Line 12 suddenly plummeted onto a stream of cars near the Olivos station in the city’s southeast.