What happened?
At 10:11 p.m., Mexico City time, on May 3, 2021 when, surprisingly, an elevated section of metro line 12 collapsed, killing 26 people and injuring another hundred . More than a year after that tragedy, there is not a single detainee, according to the authorities themselves.
Some 388 direct and indirect victims of the tragedy were interviewed. 294 opinions were also prepared in criminalistics, photography, videos, architecture, topography, structural safety, among others.
The incident was caused by a structural failure associated with deficiencies in the construction process, in the girders (beams) of the collapsed bridge there were missing bolts, there were incomplete welds and different types of cement. And some of the works did not coincide with the "plan of original design". In addition, it had been surrounded by controversy due to its flaws since the inauguration. Its nine years have been marked by closures, deterioration and repairs. (1)
- failures in the design, construction, supervision of the work and maintenance.
Information obtained from: Rodríguez, R. (2022, 3 mayo). “Un año del colapso en la Línea 12 del metro de la Ciudad de México: qué pasó y cómo avanzan las investigaciones”. CNN Español. Recuperado 15 de octubre de 2022, de:Lo que debes saber tras un año del colapso en la Línea 12 del metro de CDMX (cnn.com)
What do the investigations and expert reports say?
The final expert reports presented by a Norwegian company in September 2021 determined that structural flaws in the construction of the work, such as lack of fusion of the bolts and the beam, poorly completed or executed welds, porosity, among other deficiencies, contributed to the collapse of one of the sections of line 12, the youngest of the city's metro.
Expert reports from the Attorney General's Office of the Mexican capital also concluded that construction errors, such as poorly placed bolts or poorly made welds, were the causes, but they could not be detected in inspections since they could not be seen with the naked eye. view to be found within the structures.
"DNV points out that the collapsed section has a composite structure: a part of concrete and a part of steel, and that failures in the bolts – the pieces that join both components – caused parts of the viaduct to be damaged, that each part of that structure worked separately and will not hold the weight. "The collapse occurred as a result of buckling of the North and South Beams facilitated by the lack of functional bolts along a significant length of the beams, which caused a portion of the elevated bridge to lose its composite structure." (1)
The design, which did not adhere to what is stipulated in the American specifications for the construction of bridges, a reference standard in the rest of the world. Specifically, the company claims there were problems with five components: bolt fatigue design; the required deadweight countershaft; the joints between the elements of the transverse frames and the lower flanges of the beams; the bedding requirements for precast elements, and the lack of shear reinforcement of the interface between the precast concrete and the cast-in-place concrete.
Who participated in the construction?
Many companies and people were involved in the construction, some of them are:
- The construction company Carso (Carlos Slim)
- Associated Civil Engineers, ICA.
- Probable participation of 8 former capital officials (there are no names)
- It was inaugurated by the current secretary of foreign affairs, Marcelo Ebrard.
- Comsa Emte: Spanish company contracted to carry out the rehabilitation work on line 12.
- TÜV Rheinland de México, SA de CV: German company in charge of certifying the rehabilitation of line 12.
- Triacaud Societé Organisé (TSO): French company specializing in tracks, contracted to carry out the inventory of the physical situation of the L12 tracks and to participate in the verification of the rolling stock and railway infrastructure interface.
- Systra: highly specialized French company in the field of urban railways, contracted to diagnose the processes of basic engineering development, project bidding, project development, construction, equipment, maintenance and operation of both tracks and rolling stock.
Information obtained from: Rodríguez, R. (2022, 3 mayo). “Un año del colapso en la Línea 12 del metro de la Ciudad de México: qué pasó y cómo avanzan las investigaciones”. CNN Español. Recuperado 15 de octubre de 2022, de:Lo que debes saber tras un año del colapso en la Línea 12 del metro de CDMX (cnn.com)
All defendants can be charged with the crimes of homicide, injuries and property damage.
* Had other events like this happened before?
- The closure of a Vehicular Bridge due to the Fall of a Metal Plate in CDMX: this incident was recorded in Calzada Taxqueña and Calzada de Tlalpan, in Mexico City (CDMX).
Image and information obtained from: Cierran Puente Vehicular por Caída de Placa Metálica en CDMX (nmas.com.mx)
- Collapse of a bridge in Mexico during its inauguration: several injured, including the mayor: it occurred in the Barranca de Amanalco Park, in Cuernavaca. The accident was due to excess weight on the structure.
Image and information obtained from:Se desploma un puente en México en plena inauguración: varios heridos, incluido el alcalde (elespanol.com)
- The collapse of a suspension bridge in Cuernavaca causes at least twenty injuries: What was a celebration in the Barranca de Amanalco park in the State of Morelos, ended in tragedy. The Paseo Ribereño suspension bridge collapsed just as they were crossing it.
Image and information obtained from:El colapso de un puente colgante en Cuernavaca provoca al menos una veintena de heridos | EL PAÍS México (elpais.com)
(1). Rodríguez, R. (2022, 3 mayo). “Un año del colapso en la Línea 12 del metro de la Ciudad de México: qué pasó y cómo avanzan las investigaciones”. CNN Español. Retrieved October, 15, 2022, from:Lo que debes saber tras un año del colapso en la Línea 12 del metro de CDMX (cnn.com)
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