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Team finds structural failures, construction deficiencies cause of Mexico City metro collapse

Mexico City, Mexico — On Wednesday, Claudia Sheinbaum, head of Mexico City government, presented a report which indicated a structural failure associated with at least six deficiencies in the construction process caused the collapse of the Tezonco-Oivos interstation of Line 12 of the city’s metro system.

At a press conference, the mayor explained that the failures had to do with structural elements such as welds, bolts, foundations and concrete which were installed with failures, which in turn, caused the collapse of one of the metro girders. She said that failures were determined by inspecting company Det Norske Veritas (DNV).

According to their report, deformation was observed in the beams that make up the concrete-steel bridge, fractures in various girders and welds where the train passed. According to their opinion, during installation there were several errors. The bolt welding process was poor in various parts of the damaged section, there was porosity and lack of fusion in its installation and the distance between them was not uniform throughout and width of the work.

A remnant of the ceramic protection used during their installation was also identified around some bolts and works only as an aid to join them to the beam. That failure limited the adherence of the bolts.

DNV inspectors also noted an unfinished weld in the Bifurcation Lock at its junction with the Bridge Lock, and a total breakage of a weld in the Bridge Lock, denoting the inclusion of a foreign material (rod) approximately halfway through the the joint.

The DNV report underlines that derived from the physical and documentary review, the Metro Line 12 was operating under normal conditions in accordance with its protocols or transfer programs. Likewise, it indicates that the components of the tracks, rails, cabinets and switch motors are observed under normal conditions, complying with the routine maintenance protocols, according to the visual inspection in the analyzed area.

Preliminary results of the metro collapse were presented Wednesday

The general director of DNV Mexico, Eckhard Hinrichsen, clarified that the report presented Wednesday is the first of three. “It is preliminary, there are no final results yet.

“We continue with the investigation on several fronts. The report of phase 2 will be delivered on July 14, and that of phase 3 on August 30,” he said.

On Wednesday, Sheinbaum announced a specialized technical team will carry out the Metro L12 rehabilitation project. The team, she said, will be ready in about one month.

“With the information that we have, we have made the decision to form a technical team of the highest level to carry out an executive project for the reinforcement and rehabilitation of Line 12. I want to say that this decision has the support of the President of the Republic, the Andrés Manuel López Obrador,” she said during the press conference.

“The committee, made up of different experts, should present an executive project within a month,” she added. This will occur at the same time that the rest of the studies are carried out by the independent company DNV and the capital’s Prosecutor’s Office.

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