Mexico City (AP) —A preliminary report by experts on the collapse of an elevated subway line in Mexico City that killed 26 people was predominantly on Wednesday due to poor welding of studs connecting steel support beams to the concrete layer that supports the track floor. I took responsibility for it.

The city government hired a Norwegian certification company, DNV, to investigate the possible causes of the May 3 accident. In this accident, the span of the elevated line buckled on the ground and two subway cars were dragged in.

The report also stated that apparently there were not enough studs and the concrete poured over them could be defective. Welding between the stretches of the steel beams also seems to be poor.

“Studs have shown defects in the welding process,” the report said.

The existence of construction flaws when the line was built between 2010 and 2012 was due to the political career of the then mayor of Mexico’s top diplomat and of Mexico, where the company built part of the subway line. It can be a big blow to the wealthiest men.

The report focuses on photographs and physical inspections showing that the metal studs welded to the top of the steel support beams are broken or peeled off cleanly, suggesting weld defects. I will.

The beams themselves could not support the weight of the truck bed. The studs protruding upwards from the beams were covered with concrete slabs poured to help carry the weights.

However, it turns out that the studs still carry a ceramic ring that covers the weld. Used as a safety control method to contain molten steel, the ring should have been knocked off after the weld so that the inspector could see the weld itself. The fact that they were left in place may indicate that the welds were not properly inspected.

This is consistent with reports that the project was completed in a hurry and the current Minister of Foreign Affairs Marcelo Evrad was able to open subway line 12 before resigning as mayor in 2012.

This section was built by a company owned by Carlos Slim, now the wealthiest in Mexico and once the wealthiest in the world, a tycoon in the telecommunications and construction industry. Slim is a trained engineer and his company is currently involved in building some parts of the controversial Maya Train project around the Yucatan Peninsula.

The proposal that his company did a crude job on the subway would seriously hurt his reputation as a kind of senior politician in the Mexican business community.

The $ 1.3 billion Line 12, the latest section of the vast subway system that opened in 1969, was unlucky from the start. The cost of the so-called gold line was halved, construction was delayed repeatedly, and allegations of design flaws, corruption and conflicts of interest were encountered.

The top executive of the company that made it was the brother of the man who oversaw the project for the government.

A scandal over the forced closure of an expensive new line in 2014 (only 17 months after its inception) essentially put Evlad into political asylum. He was rescued by his patron Andres Manuel Lopez Obrador, who helped him become mayor in 2006 and revived him by appointing him as a diplomatic secretary in 2018.

Despite the subway scandal, Ebrard was responsible for Mexico’s efforts to obtain the coronavirus vaccine and was considered a top candidate for the success of Lopez Obrador in 2024.

Mr Ebrard said he would cooperate in investigating the accident last month.

Earlier reports by engineering companies revealed that the Evlard Municipal Government made a series of surprisingly wrong choices when designing and constructing subway lines.

Experts say the unusually sharp curves of the route exacerbated the problem of wheel-on-steel truck design, which is more like the New York Subway than the European-style rubber tires used in other parts of the system. Said.

The Gold Line line chattered, bumped and screamed. The rails began to take a wavy pattern. The driver had to slow down the train to 3 mph (5 km) on some sections.

In 2014, the Goldline had to be shut down for several months in order to replace or shape the truck.

Some say that ballast was added between the train tracks during these repairs, and extra weight and the possibility of poor maintenance could have been potential factors for the collapse.

A 2017 official survey of the damage caused by a magnitude 7.1 fatal earthquake showed signs of construction flaws. Authorities have decided to patch quickly, weld stanchions under curved beams, and resume service.

Evrad claims that subsequent investigations showed that the line was determined to be in compliance when it was built. “Most of the oversight and maintenance that was left to the administration that took over me remains unknown,” he wrote.

After a previous investigation into design and corruption, more than 38 civil servants received fines or other penalties for improperly undertaking work on trains, and several criminal charges.

Many routes have been closed since the May accident. The elevated section of the track is about 16 feet (5 meters) above the median strip and driveway in the poor southern part of Trauak. Elongated reinforced concrete columns are covered with horizontal steel beams. The beams support the prefabricated concrete track floor on which gravel, sleepers and tracks are laid.

Serving 4.6 million passengers daily, the Mexico City subway didn’t have one of the most needed. It’s money. Tickets are priced at only 25 cents per ride, one of the lowest in the world, so the system stays away from paying its own costs and relies on huge government subsidies. I will.