Construction failures and repairs
Semanas antes de su inauguración, se detectó un desgaste anormal de los rieles en dos curvas del tramo elevado,[33] por lo que se tuvo que hacer un reperfilado y sustituir 900 metros de riel.[34] Cabe señalar que a pesar de que la línea comenzó operaciones hasta octubre de 2012, desde el domingo 17 de junio de ese año, se ofrecieron recorridos gratuitos de manera semanal o quincenal, haciendo paradas en determinadas estaciones, tanto para conocer el trayecto como las estaciones.[35].
El 26 de julio de 2013, una porción del techo de plafón de la estación Hospital 20 de Noviembre "Hospital 20 de Noviembre (estación)") colapsó y se precipitó a las vías, provocando la interrupción del servicio por algunos minutos, no se reportaron personas lesionadas sin embargo el servicio fue suspendido de la estación del incidente a la terminal Mixcoac "Mixcoac (estación)"); para esta fecha, la línea tenía casi 9 meses de haber iniciado operaciones de manera oficial.[36] Por esas mismas fechas, el Sistema de Transporte Colectivo (STC) anunció el primer cierre de operaciones parcial y solicitó al consorcio constructor de la línea 12, formado por las empresas ICA, Carso y Alstom, la renivelación de los rieles entre las estaciones Culhuacán "Culhuacán (estación)") y Calle 11 "Calle 11 (estación)"). La suspensión del servicio de trenes se realizó durante los fines de semana entre el 2 de agosto y el 30 de noviembre de 2013.[37][38] Semanas más tarde, el 4 de octubre de 2013, inició otro periodo de mantenimiento desde la estación terminal Tláhuac "Tláhuac (estación)") hasta la estación Tezonco "Tezonco (estación)").[39].
First suspension of operations
On February 17, 2014, another maintenance period began to relevel and readjust the rails, compact the ballast, and tighten and/or replace the rail and sleeper fastening elements. During service hours it was decided to operate the trains at a speed of less than 35 km/h called safety run. Consequently, an increase between 7 and 10 more minutes was recorded in the total travel time.[40][41] On March 11, 2014, Joel Ortega Cuevas, then director of the STC, announced the suspension of the service for an indefinite period between the Tláhuac terminal "Tláhuac (station)") and the Culhuacán station "Culhuacán (station)") due to the serious failures detected in the elevated section, which which increased the possibilities of derailment of the trains.[42] Some media showed photographs and videos showing longitudinally fractured concrete sleepers, fractured fastening elements, undulatory wear on rails and wear on the steel wheels of the trains.[43][44][45] As a consequence of the suspension of the service, authorities of the then Government of the Federal District, former officials of the 2006-2012 administration and representatives of the construction consortium, blamed each other for the failures on the line. This caused the Legislative Assembly of the Federal District to create a commission on March 18, 2014 to determine the causes of the failures. This commission was made up of 15 deputies from all political factions and chaired by deputy Jorge Gaviño Ambriz of the Nueva Alianza party.[46].
On March 19, 2014, the director of the Federal District Metro Project, Enrique Horcasitas, was removed from his position by Miguel Ángel Mancera, under the argument of guaranteeing a transparent investigation into the failures on line 12. –director and former director of the metro, respectively–[49][50] and of Grupo ICA, Alstom Mexicana and Grupo Carso, –construction consortium of the work–,[51] DB International, ILF Baratende, Tuv Sud Rail and Hamburg Consult –certifying consortium of line 12–, Construcciones y Auxiliar de Ferrocarriles –constructor of rolling stock– and Impulsora Tlaxcalteca de Industrias –supervisor of the work–[52].
In an interview offered to the media, Miguel Ángel Mancera mentioned that he will deliver the technical opinion requested from the European companies Travaux du Sud-Ouest and Eurovia Travaux Ferroviaires[53] to the Comptroller General of the Federal District, which is also carrying out a technical study advised by the company SGS. Hiram Almeida Estrada, head of the comptroller's office, mentioned that the objective of these studies is to establish the corresponding responsibilities and allow the carrying out of the appropriate legal actions.[54][55].
Weeks later, on March 27, the company Eurovia Travaux Ferroviaires announced its withdrawal from the diagnostic work carried out on line 12 for unknown reasons;[56] days later the French railway company Systra was hired by the government of the Federal District and replaced by Eurovia Travaux Ferroviaires. Systra continued working together with Travaux du Sud-Ouest on the diagnostics of the aforementioned line. On April 4, 2014, the Political Coordination Board of the Chamber of Deputies created a commission to monitor the federal resources assigned to the construction of metro line 12.[57] On April 8, 2014, Joel Ortega appeared before this commission to explain the destination of the federal funds assigned to line 12.[58].
Executive rehabilitation project (Tláhuac-Atlalilco)
On September 4, 2014, the companies Systra and TSO delivered the diagnosis carried out by these companies over several weeks. Said diagnosis explains the failures detected in the infrastructure, as well as the respective solution to them. It was concluded that there were general errors in operation, design and maintenance throughout the road. The report proposes 32 corrective actions and the replacement of at least 312,000 parts in the stopped section alone. Some actions to execute are the following:[59][60][61].
• - Modify the layout of curves 1 and 2 located in the workshops of the Tláhuac station "Tláhuac (station)"), in order to increase their radii so that the trains can maneuver easily.
• - Level the entire track and mold the rails to obtain the profile with "UIC60" specification.
• - Modify the profile of the train wheels to adjust it to the French standard "NF-F-03-402" with an adaptation to obtain a flange width of 31.5 mm.
• - Replace approximately 14,000 m³ of ballast with one of the "C4" type.
• - Replace approximately 15,000 meters of rail.
• - Modify the superelevation in 15 curves, from 160 to 100 mm.
• - Change approximately 15,000 fixing pieces (needles and staples) for "Vipa" brand ones.
• - Replace 12,500 sleepers with Sateba brand sleepers").[62].
• - Change points in 26 track devices.
• - Make 954 welds.
• - Grind 3,412 welds with defects.
Systra and TSO will supervise the maintenance work, according to the authorities of the Government of the Federal District;[63] they also declared that an executive project will be required to rehabilitate the line which must be designed by all parties involved.
On September 29, 2014, the Secretariat of Works and Services of the Federal District announced that line 12 will operate fully until the end of 2015, making partial reopenings starting with the Culhuacán and San Andrés Tomatlán stations in May, while Lomas Estrella, Calle 11 and Periférico Oriente will reopen in June, ending with the reopening from the Tezonco station to the Tláhuac terminal in November 2015.
The rehabilitation of the affected section did not begin until early 2015, due to a lack of resources from the previous year according to statements by the authorities of the Government of the Federal District. They also declared that the costs of the rehabilitation of the line will be 893 million pesos.[64].
2015
For that year, major maintenance work between the Tláhuac and Culhuacán stations officially began, according to the executive project announced in mid-2014; Said works were extended throughout that year, to begin with partial reopenings during 2015. However, despite the intention of the Ministry of Works and Services to reopen stations in this way, this possibility was ruled out, to reopen the entire rehabilitated section in November of the same year as the Head of Government had promised.
From September 4 to 6, 2015, dynamic tests were carried out on the Nopalera "Nopalera (station)")-Zapotitlan "Zapotitlán (station)") section, which was 100% rehabilitated; For this, all rails, sleepers, staples and ballast were replaced with new materials and based on Systra specifications. The tests were also carried out with a train modified in the same way based on Systra specifications.[65][66][67] The results of these tests were obtained on September 7 and were sent for evaluation in French laboratories, although at the time it was confirmed that the tests were successful. and the same line of rehabilitation would be followed in the rest of the affected section.[68].
Weeks later, the head of government Miguel Ángel Mancera confirmed November 30, 2015 as the deadline for the completion of rehabilitation work and the immediate restart of operations on the entire line.[69][70] Additionally, the underground section will also be subjected to corrections and major maintenance, although this would be carried out without suspending service on said section.
Subsequently, the director of the Metro Collective Transportation System that year, Jorge Gaviño Ambriz, declared that the restart of operations will be with 15 rehabilitated trains and 15 unrehabilitated, as a consequence the line would operate with contingency speeds (35 km/h and 50 km/h) as long as the rehabilitation is not completed in both the remaining trains and the underground section, although he did not specify a date for the conclusion of these works.[71].
In mid-October, the head of government Miguel Ángel Mancera considered the reopening of the section between Culhuacán "Culhuacán (station)") and Periférico Oriente "Periférico Oriente (station)") at the end of that month, however he declared that it would depend on the decision of the certifiers, and if approval was not granted, the restart date of operations would be maintained no later than November 30 in the 11 stations out of service.[72][73].
On October 27, 2015, the director of the Metro Collective Transportation System, Jorge Gaviño Ambriz confirms the restart of operations at the stations Periférico Oriente "Periférico Oriente (station)"), Calle 11 "Calle 11 (station)"), Lomas Estrella "Lomas Estrella (station)"), San Andrés Tomatlán "San Andrés Tomatlán (station)") and Culhuacán "Culhuacán (station)") starting the next day, October 28 at 11:00 GMT -6 (17:00 GMT) and in the usual metro service hours from October 29.[74][75] Meanwhile, the Periférico Oriente station would serve as a provisional terminal until the work on the remaining section was completed, from the Tezonco station "Tezonco (station)") to the Tláhuac terminal "Tláhuac (station)"), while the free service with RTP trucks would now be offered from Periférico Oriente to Tláhuac.
2016
In June 2016 it was confirmed that the Metro Collective Transportation System is working on a biannual project to carry out major maintenance of a second track sector of line 12, corresponding to the underground section from the Atlalilco station "Atlalilco (station)") to the Mixcoac terminal station "Mixcoac (station)"); Jorge Gaviño Ambriz, director of the transportation organization, reported that the project is under development and that the rehabilitation work would be carried out at night with the aim of not affecting the service. Likewise, the works would begin in 2016 and would extend to 2017, taking approximately 13 months.
The maintenance according to Gaviño, would consist of carrying out the same intervention procedure carried out in the first stage of the maintenance of line 12 (Tláhuac "Tláhuac (station)")-Atlalilco "Atlalilco (station)"), executed during 2014 and 2015; The rails would be replaced with ones with the "UIC60" profile, placed with Sateba brand sleepers), replacement of fixings with ones from the "Vipa" brand, and replacement of the ballast with one of the "C4" type, in addition to the recommendations indicated by Systra in the first stage of maintenance.[78][79].
In August 2016, Gaviño Ambriz reported that to begin maintenance, priority will be given to the curves that present the greatest wave wear, and that to begin said work the section of tracks located between the stations Atlalilco to Parque de los Venados "Parque de los Venados (station)" is contemplated. The works would begin in December 2016 and would be extended in 2017, carrying out the work at night for 3 hours and 30 minutes daily without suspension of the train service. The budget considered for this second maintenance stage is 800 million pesos.[80][81].
2017
On September 19, 2017, a magnitude 7.1 earthquake hit Mexico City and some surrounding states. As a consequence, the Collective Transportation System was forced to suspend service between the stations Tláhuac "Tláhuac (station)") and Culhuacán "Culhuacán (station)")[82] (mainly due to the minor derailment of a train at the Nopalera "Nopalera (station)")-Zapotitlán "Zapotitlán (station)" interstation without any injuries[83] and a power failure) while the state of the facilities was evaluated. A few hours later it was reported that the train had already been rerouted, but the service was still suspended on the elevated section.[84] On September 20, the STC, through its official Twitter account, reported that the service on line 12 would be to the Periférico Oriente station "Periférico Oriente (station)")[85] while they continued to evaluate the status of the suspended section, and 50 units of the M1 system were assigned to serve users on the section. suspended.[86].
On September 21, service between the stations Tezonco "Tezonco (station)") and Tláhuac "Tláhuac (station)") continued to be suspended. However, it was announced that, as a result of the evaluations, the following problems were found:[87].
• - Visible damage to roads.
• - Structural failure in a column between the Olivos "Olivos (station)") and Nopalera "Nopalera (station)" stations, located at the intersection of Gitana Street and Tláhuac Avenue. This column fell on this last road on the night of May 3, 2021.
• - A hidden defect was detected in the assembly of the aforementioned column, in the assembly of the rings in the lower part of the column, so all the columns of the elevated viaduct will be reviewed.
• - Displacement in the support head of a girder placed in curves 11 and 12 (Nopalera "Nopalera (station)")-Zapotitlán "Zapotitlán (station)")).
• - Break in the firefighting system of the Nopalera station "Nopalera (station)").
On September 22, after the corresponding verifications, service was enabled at the Tezonco "Tezonco (station)") and Olivos "Olivos (station)" stations, the latter functioning as a provisional terminal.[88] It was also confirmed that the M1 system will continue to provide service on the suspended section. On September 24, it was reported that the Nopalera "Nopalera (station)")-Tláhuac "Tláhuac (station)") section would remain closed for at least 4 weeks to carry out the repair on the column and the change of elements in curves 11 and 12.[89] Service at all stations on the line resumed on Monday, October 30, after several operational tests.[90].
2023
On January 15, 2023, metro line 12 was reopened in its underground section, from the Atlalilco to Mixcoac stations, just 8 days after the 2023 Mexico City Metro train collision.[91] On July 15, five stations on the line returned to operation, from Culhuacán "Culhuacán (station)") to Periférico Oriente "Periférico Oriente (station)").[92].