More cracks found in Mexico City subway line that collapsed

MEXICO CITY — Inspectors have found 21 more cracks in welds or steel structural pieces on an elevated subway line that had a section collapse in May, killing 26 people, officials said Wednesday.

Studies on the fallen section found the failure was caused by construction defects like poor welds and missing connection studs as well as bad design. These cracks were found in other sections of the line which didn’t fall.

The inspection is only about one-third complete, so more such defects may be uncovered.

Outside inspectors have been invited in as part of efforts to re-open and reinforce the line, including some from the Autonomous University of Nuevo Leon.

Telecom and construction magnate Carlos Slim has said his Grupo Carso’s construction subsidiary will pay the cost of rebuilding the span that collapsed and reinforcing other parts of the elevated line to meet higher standards in a city plagued with severe earthquakes.

Earlier this year, Mexico City prosecutors announced criminal charges against 10 “individuals and companies” for construction and design defects.

In the case of the companies involved, prosecutors have said the goal of the criminal charges is aimed at making them pay for or repair damages both to the subway and the victims. These charges include negligent or involuntary murder, damage and causing injury.

Inspections of the collapsed section cited poorly welded, badly located and completely missing studs that were intended to join steel support beams to a concrete layer supporting the track bed.

Prosecutors also cited bad welds in the steel beams underlying the concrete track bed that either failed to adhere or split. The steel struts that were intended to stiffen the beams weren’t properly or too short. Also, the elevated line wasn’t designed with sufficient safety margin.

In the past, some companies involved in building the line more than a decade ago have claimed that subsequent repair work put too much weight on the elevated section.

The $1.3 billion Line 12 of Mexico City’s metro system was built between 2010 and 2012 when current Foreign Affairs Secretary Marcelo Ebrard was the capital’s mayor. Ebrard has been considered one of the most likely candidates to succeed President Andres Manuel L√≥pez Obrador.

The project was plagued by cost overruns and alleged design flaws, corruption and conflicts of interest.

The city was forced to close the line in 2014, just 17 months after it was inaugurated, so tracks could be replaced or repaired. Since May, the section which collapsed was still closed.

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