MEXICO CITY — The Mexico City elevated subway line that collapsed this week, killing 25 people, was problem-plagued and poorly designed from the day of its inauguration in 2012.
Passengers and authorities alike came to fear that the screeching and bouncing of wheels on the line’s tight curves were quickly wearing away the tracks, raising fears of a derailment.
But few expected the thing would simply collapse.
However, an official 2017 survey of damage caused by a deadly 7.1 magnitude quake showed indications of construction defects that should have shut the line down immediately, according to an experienced structural engineer.
José Antonio López Meza said the defects detected in the subway system report — a sagging section of too-weak steel near the latest accident — is the kind of thing that could have contributed to Monday’s collapse.
Instead, authorities decided on quick patches, welding props under the bowed beams and reopening service.
"Nothing is taken care of until a tragedy occurs"
“Here in Mexico, nothing is taken care of until a tragedy occurs,” said López Meza, who also is a seismic consultant who has worked on government projects. He said they are often not held to the same on-site inspection standards as private builders.
But authorities weren’t concentrating on structural defects. They had their hands full over the last decade simply trying to keep the subway train on its tracks, to avoid what could arguably have been have an even more nightmarish failure than Monday’s collapse involving two subway cars.
The $1.3 billion Number 12 Line, the newest section of a vast subway system opened in 1969, was ill-fated from the start. The so-called Gold Line cost half again as much as projected, suffered repeated construction delays and was hit with allegations of design flaws, corruption and conflicts of interest.
A top executive of one of the companies that built it was the brother of the man who oversaw the project for the government.
The scandal over forced closure of the costly new line in 2014 — just 17 months after it was inaugurated — essentially forced former Mexico City Mayor Marcelo Ebrard into political exile until he was rescued by his patron, new President Andrés Manuel López Obrador — who had helped make him mayor in 2006 and resuscitated him by naming him foreign relations secretary in 2018.
Despite the subway scandal, Ebrard was put in charge of Mexico’s efforts to obtain coronavirus vaccines and was considered a top contender to succeed López Obrador in 2024. That was before Monday’s accident. Ebrard has said he’ll cooperate with the investigations.
Reports by engineering firms revealed Ebrard’s city government had made a series of startlingly wrong choices when the subway line was designed and built between 2008 and 2012.
Experts said unusually sharp curves in the route exacerbated problems with the wheels-on-steel track design, which more resembles New York’s subway rather than the European-style rubber tires used on the rest of the system.
The Gold Line line chattered. It bumped. It shook. It screeched. The rails began to take on a wavy pattern. Drivers had to slow trains to as little as 3 mph (5 kph) on some stretches.
In 2014, the Gold Line had to be shut down for months for the tracks to be replaced or ground into shape.
Following investigations into the design and corruption scandals, more than 38 government employees were hit with fines or other punishments for improperly contracting out work on the train, as well as some criminal charges.
According to a 2014 congressional report: “If the rails are unprotected and the shape of the wheels doesn’t comply with international standards, we have a potential risk of derailment.” The probe concluded the line should have use rubber-wheel suspension, rather than railroad-style steel wheels, but by then it was too late to change.
But most reports had cleared the elevated track bed of any structural concerns until the 2017 quake revealed what the subway line was made of.
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May 06, 2021 at 03:06AM
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Mexico City subway collapse was a tragedy foretold - NBC News
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