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.
Posts: 9975 | From: Clarendon Hills, IL USA (BNSF Chicago Sub MP 18.71) | Registered: Apr 2002
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Mexico City Metro appears to be a steel wheel on steel rail system as opposed to the earliest line rubber tire system. One of the early Taipei Metro lines was also a French rubber tire system line, the Mucha line which was mostly aerial.
While the rubber tire system may be OK in France with their more northerly latitude, the heat produced by tire flexure, about 4 times that of a steel wheel is my understanding, is a real issue in hotter average temperature climates. That, with the high passenger loading compared to that in France, probably had a lot to do with the concept not being repeated in either city. Not incidentally, this tire flexure means more energy consumed to drive the trains as well.
Back to the accident at hand, it appears that it is entirely a structural failure. I will make no comment about construction quality or possible payoffs, but to say this sort of thing absolutely should not happen except under major earthquake or some form of extreme overload, neither of which seem to be in play here.
Posts: 2808 | From: Olive Branch MS | Registered: Nov 2002
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An update on the Mexico City Metro structure collapse: Some things learned since:
This is the newest line on the system,
Where: Line 12 of Mexico City Metro, in borough of Tlahuac, near Olivos Station
When: May 3, 2021, 22:25 CDT
Appears that a pier collapsed, bringing down the adjacent spans. From: https://thehill.com/policy/international/americas/571376-poor-welds-blamed-for-fatal-mexico-city-subway-collapse The report by Norwegian certification firm DNV, which was commissioned by the Mexico City government to investigate the subway overpass collapse, found that poor installation of studs resulted in “two independent parallel beams, a concrete beam and steel beam, that experienced loading conditions for which they were not designed,” according to The Associated Press. "This created conditions that led to the distortion of the central transverse frame and the initiation and propagation of fatigue cracks that further reduced the capacity of the structure to support the load," the report added, Reuters reported.
In other words: Construction quality, or rather the lack thereof.
Posts: 2808 | From: Olive Branch MS | Registered: Nov 2002
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