Mexico City subway overpass collapses, killing at least 23 and injuring dozens 2

[dauwerda]

According to the story, this section of the line was built in 2012.

https://www.cnn.com/2021/05/04/americas/mexico-subway-collapse-intl-hnk/index.html

The very beginning of this video shows the collapse via security camera footage.

https://www.cnn.com/videos/world/20...hnk-vpx.cnn/video/playlists/around-the-world/

 

[LittleInch]

There is a cross over from one track to the other.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[ImminentCollapse]

LittleInch,
The truss you refer to is called a cross-fame, used for lateral stability during construction and to account for lateral load transfer such as wind between the girders. Also, if the top flange was unbraced (non-composite), it would provide top flange bracing in the final condition. It does not look like that was the intent though. I noticed it earlier too, it is puny in my experience, especially for a light rail bridge. It does give the appearance that it is buckling.

IC

 

[azcats]

[URL unfurl="true"]https://www.manufacturing.net/safety/news/21415806/mexico-city-subway-collapse-was-a-tragedy-foretold[/url]

 

[FacEngrPE]

Forensics Firm DNV Tapped to Probe Mexico City Subway Collapse (ENR) Norwegian risk management firm DNV will lead an independent forensic investigation into Mexico City’s subway overpass collapse.
Using a foreign firm is likely an effort to ensure the appearance of a politics free investigation.

 

[Ingenuity]

==> Follow-up 06/13/2021:

NY Times is reporting the following, that the steel studs that make the steel beams & concrete slab composite were poorly welded:

Link

 

[FacEngrPE]

No paywall New York Times reveals that the CDMX subway collapsed due to government rush to inaugurate it; by Explica .co June 13, 2021, 8:46 pm
Composite action problems were suspected earlier in the thread.