Why subway line 12 collapsed: political opportunism and sloppy construction, according to the New York Times

After more than a month of the accident on line 12 of the Metro Collective Transportation System in Mexico City (CDMX), the American newspaper The New York Times revealed an investigation which assures that serious construction failures directly led to the crash. of the two wagons.

In addition, the newspaper accused in its investigation that political expediency and neglected work were the main causes of the crash that claimed the lives of 26 people. “The disaster has already turned into a political crisis that threatens to trap two of the country’s most powerful figures: the President’s Foreign Minister, Marcelo Ebrard, and one of the richest businessmen in the world , Carlos Slim. article.

Through photos, the engineers consulted concluded that the welds of the Line 12 viaduct showed “critical errors”, which represented a high risk of being “vital to the strength” of the construction. In fact, alleged CDMX officials and people familiar with the investigation pointed to a pattern of “political expediency and disorderly work during the construction of the metro”.

According to the report made with the initial evidence, the steel beams were not built to support the structure by itself, so metal posts were placed to connect the steel to the concrete slab, despite the fact that these two materials are stronger in one unit. .

The studs were welded to steel, creating an “almost unbreakable, according to NYT,” but photos of the debris suggest to engineers the welds were poorly made, a serious construction flaw. In addition, the engineers would have found another major flaw: the workers did not remove the ceramic rings that surrounded the studs when placing them.

These placement errors would cause that on May 3, around 10 p.m., the welds and bolts broke the steel, causing two wagons of a 12-meter train to fall into the void.

“When the train made its last trip, it is likely that some sections of the concrete disconnected, simply resting on steel beams that were never designed to support weight alone,” the NYT investigation notes.

The media assure that one of the assumptions, although not definitive, is that during the passage of the train, the beams slipped inward and the support of the structure bent, allowing the vehicle which passed over- above falling.

All this comes less than 10 years after the start of the operation of the Line inaugurated by Marcelo Ebrard, one of the possible candidates for the presidency. However, The New York Times revealed that an analysis of internal and corporate documents revealed “more than a decade of warnings and safety issues before the fatal crash.”

Information under development …