Mexico City Metro elevated subway section collapses, 23 killed so far

https://www.reuters.com/world/americas/ ... 021-05-04/

At least 23 people were killed and 65 were hospitalized when a railway overpass and train collapsed onto a busy road in Mexico City on Monday night, crushing cars under fallen carriages and rubble.

The authorities halted rescue efforts shortly after they began, saying there was a risk that more train parts and debris could slam down onto the road.

A video on local channel Milenio TV showed the structure plummeting onto a stream of cars near the Olivos station in the southeast of the city at around 10.30 p.m. local time, sending up clouds of dust.

Not to minimize the tragic impact of this incident in the least, CDMX's system is rubber tired atop concrete "rails". This is same as Paris, Miami Metro Mover, Detroit, and who knows where else I've been in this world that has same, but does not come readily anymore to this almost 80yo mind.

Gilbert B Norman wrote: ↑Tue May 04, 2021 6:59 am Not to minimize the tragic impact of this incident in the least, CDMX's system is rubber tired atop concrete "rails". This is same as Paris, Miami Metro Mover, Detroit, and who knows where else I've been in this world that has same, but does not come readily anymore to this almost 80yo mind.

This is Line 12. It's traditional steel wheel on metal rail. https://en.wikipedia.org/wiki/Mexico_City_Metro_Line_12

Stand Corrected, Mr. Wolf:

https://www.msn.com/en-us/news/world/me ... d=msedgdhp

Photo clearly shows steel rail and a truck with steel wheels.

Meantime, the finger pointing "blame game" hath beginneth . Something tells me they are quite proficient at such down there.

From a fellow artist who lives in Mexico:

Yeah that happened. The subway route that has been questionable since the beginning, done cheaply and tons of obvious corruption, finally took@its toll

MSN notes the line is maintained by a third party contractor. NBCNews has a reporter digging into it as well, and had a report from Mexico City for the Today show.

CBS Radio News reports the outside contractor is a French concern.

"Smell the Tacos a cookin'"

BTW; Not The First This one on the rubber tire lines I rode during '75.

Here's a New Zealand source reporting on the possible "French Connection" :

https://www.rnz.co.nz/news/world/441860 ... adly-crash

Apparently, CBS News could have been confused in that Alstom built the cars, and could easily hold a maintenance contract for such. But it appears the incident lay with a structural failure and not rail equipment.

Somebody knew there was trouble even as early as '14.

Gilbert B Norman wrote: ↑Wed May 05, 2021 7:23 am ...But it appears the incident lay with a structural failure and not rail equipment.

Somebody knew there was trouble even as early as '14.

I'm so expecting that when they sonar scan the pillars, instead of rebar it's empty beer cans. The locals (from what I'm hearing from my fellow artist there) that there was tons of cash allotted to the project... and that corruption was guaranteed.

Rebar is a continuing problem. Some university engineering departments have turned to electron microscopy to look at imported steel in sign and light standards too. There's even some evaluation of using stainless steel rebar in concrete. Also, there's already high-strength patented concrete with impregnated plastic fiber.

Did this elevated suffer from single-point-of-failure design, or just general weakness?

While all the above are possibilities, who designed the bridge? Is it possibly the same company that designed the bridge in Florida that collapsed while being placed ? That same company is responsible for the collapse of the Florida bridge and one other from what was in the news at the time.

Really a sad story. RIP to those who lost their lives in what (probably) should have been a preventable accident. What a waste.

The New York Times has an investigative and interactive report appearing today. It appears that it will address how the quite apparent infrastructure failure occurred, as well as the political and sccial ramifications resulting therefrom:

Fair Use:

But a New York Times investigation — based on years of government records, interviews with people who worked on the construction, and expert analysis of evidence from the crash site — has found serious flaws in the basic construction of the metro that appear to have led directly to its collapse.

The disaster has already spiraled into a political crisis, threatening to ensnare two of the nation’s most powerful figures: the president’s foreign secretary, Marcelo Ebrard, and one of the world’s wealthiest businessmen, Carlos Slim.

It's lengthy, and I have not sufficiently read to offer any comments.

Going through the report...

Marcelo Ebrard was Mexico City's mayor when the Golden Line was built. Carlos Slim's construction company, Carso Infrastructure and Construction, built that section of line (their first rail project).

The steel studs that were vital to the strength of the overpass -- linchpins of the entire structure -- appear to have failed because of bad welds, critical mistakes that likely caused the crash.

The article goes into the construction, how steel I-beams were put up to hold up the track, but required the concrete to properly support it. This concrete was to be rooted in by use of metal studs that were welded in place. Photos of the rubble suggest poorly done welds and unremoved ceramic rings around the studs. It's theorized that the concrete became free-floating, and caused the steel beams to buckle inwards and collapse. Much of it based on public photographs and video of the accident, which are reproduced in the article.

The shoddy construction is being found in other work done by Carlos Slim's construction company and may catch the current Mexican president in the mess. The push to open before the mayor's term was up caused a mess of planning, bad oversight of the construction, incompatibilities with provided trains, and tons of documented errors dating back to 2014 and 2017. This will ensnare a few more politicans as well.

You can try to blame the construction company or shoddy welding, but don't forget there were inspectors who signed off on it, and the agency's own inspectors should have laid eyes on the failed structure daily. This didn't happen without warning signs.

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eolesen wrote: ↑Sun Jun 13, 2021 8:45 pm You can try to blame the construction company or shoddy welding, but don't forget there were inspectors who signed off on it, and the agency's own inspectors should have laid eyes on the failed structure daily. This didn't happen without warning signs.

Just like there are warning signs with viaducts, or bridges if you prefer, in the rest of the world in the last 5 years including ;
Russia, Mexico, Canada, Italy, France, China, England, Brazil, India, United States, Indonesia, Chile, Romania, Myanmar, Columbia, Chez Republic, Greece, Israel, South Africa, and Kenya.
https://en.wikipedia.org/wiki/List_of_b ... %93present
Many of these nations made the list more than once. I do not recall any President, Premier, Governor, Mayor, or other career politician being blamed for the failures.

My point is that politicians do not build anything, they con us the taxpayers to pay some contractor to build bridges or viaducts, at the cheapest prices possible. They pay some inspector, either a public and/or private employee, to do all the inspections. All they do is choose the contractor building the specific infrastructure - usually to the lowest bidder. It is not a scenario limited to just Mexico.

Which reminds me of a joke often told by Neal Armstrong. It goes something like this "A pessimistic calls a half full glass half empty, a optimistic calls a half empty glass half full, an engineer would state the glass is twice as large as it needs to be."

The purpose of any investigation into this failure should be to eliminate future failures, it should not be used to asses blame.