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Re: Steel beam
Author: *
Date: 05-04-2021 - 11:41
Someone on TO has some insights...
[www.trainorders.com]
Date: 05/04/21 02:38
Re: Mexico City rail bridge collapse
Author: ats90mph
I wish I could say this was surprising, the elevated section of Linea 12 in Tlahuac has had multiple issues since it opened in 2012. In 2014 the elevated section had to be closed for over a year. With only two years of service, the geometry of the track was so out of alignment, several kilometers of rail and ties had to be replaced, along with renewed ballast. Wheelsets on many of the trains were so warn, they had to be removed from service. In the 2017 earthquake, several spans nearly collapsed after several of the piers failed, and several seismic retainers snapped loose...
After a cursory look at the span that collapsed tonight I saw some interesting things. This span has a two tracks and a switch on it (for a siding). Despite this there are only two girders for the span, along with a smaller skewed girder that meets the main girder under the switch. The adjacent span has three full girders for comparison. In addition this span also carries quite a bit of catenary gear. Looking at the accident photos, the girder appears to have failed right underneath the switch, where the smaller girder meets the main girder. Was the load factor insufficient for this span? Dunno, but this failure, and the other issues this viaduct has had in it's short life, you have to wonder...
I would love to know which engineering firm designed the viaduct. The track materials were sourced from several European countries (France, Spain, UK)...
Edit: My above question was answered in the following article (in Spanish, but easily translatable). The engineering was done by Alstom and a company owned by Carlos Slim. The article also details the issues the line has had...
[expansion.mx]
Edit: This survelliance video also shows the span failing in the area directly below the switch...
[twitter.com]
Photo showing possible failure point. Photos from Google...
Edited 5 time(s). Last edit at 05/04/21 04:12 by ats90mph.
[www.trainorders.com]
Date: 05/04/21 02:38
Re: Mexico City rail bridge collapse
Author: ats90mph
I wish I could say this was surprising, the elevated section of Linea 12 in Tlahuac has had multiple issues since it opened in 2012. In 2014 the elevated section had to be closed for over a year. With only two years of service, the geometry of the track was so out of alignment, several kilometers of rail and ties had to be replaced, along with renewed ballast. Wheelsets on many of the trains were so warn, they had to be removed from service. In the 2017 earthquake, several spans nearly collapsed after several of the piers failed, and several seismic retainers snapped loose...
After a cursory look at the span that collapsed tonight I saw some interesting things. This span has a two tracks and a switch on it (for a siding). Despite this there are only two girders for the span, along with a smaller skewed girder that meets the main girder under the switch. The adjacent span has three full girders for comparison. In addition this span also carries quite a bit of catenary gear. Looking at the accident photos, the girder appears to have failed right underneath the switch, where the smaller girder meets the main girder. Was the load factor insufficient for this span? Dunno, but this failure, and the other issues this viaduct has had in it's short life, you have to wonder...
I would love to know which engineering firm designed the viaduct. The track materials were sourced from several European countries (France, Spain, UK)...
Edit: My above question was answered in the following article (in Spanish, but easily translatable). The engineering was done by Alstom and a company owned by Carlos Slim. The article also details the issues the line has had...
[expansion.mx]
Edit: This survelliance video also shows the span failing in the area directly below the switch...
[twitter.com]
Photo showing possible failure point. Photos from Google...
Edited 5 time(s). Last edit at 05/04/21 04:12 by ats90mph.
