The only possibility to reopen line 12 of the Metro is to dismantle the elevated viaduct and replace it with a tunnel, which means a greater economic cost and time, considered the civil engineer Enrique Rodríguez Ramírez. He affirmed that said work is a “disgrace to Mexican engineering,” which until the 80s of the last century was a world example in soil mechanics, structures and hydraulic engineering.
When interviewed by a local newspaper, he explained that the accident at the Olivos station that occurred a week ago, which left 26 people dead and dozens of injured, could be a consequence of the fact that the ground where the elevated part of line 12 was built was not It is ideal for the location and foundation of the work, the columns and whales (horizontal elements) were built with two different materials, as well as due to failures since it was conceived.
With a history of 50 years, both in the public and private sectors, Rodríguez Ramírez stressed: “My proposal is to dismantle that work (the elevated viaduct), put it in a place with better soil for rail purposes and build the Metro line as originally it was thought: underground. It is not easy, but it is possible. Of course there is a cost and it will be difficult for them to make that decision, ”he said.
A graduate of the National Autonomous University of Mexico, Rodríguez Ramírez worked in the construction of the eastern interceptor of the deep drainage, in the first stage of the El Rosario housing complex, was an advisor in the Ministry of Works and Services in the management of Jorge Arganis and served as a private consultant. He asserted that “something that is wrong does not need maintenance, you have to remove it, because the error is from the beginning, since it was built.”
He explained that the elevated viaduct of the so-called golden line was built on the shore of the Xochimilco and Chalco lakes, an area that is geotechnically called an “abrupt transition”, that is, it is very heterogeneous, with loose rock, silty clay, a “lousy building material”. It is a soil in which procedures had to be carried out for its treatment and improvement to achieve “a harmonious interaction between the soil and the structure.”
He pointed out that “a huge mistake, for me,” is that the columns were made of concrete with steel, materials with different modulus of elasticity, that is, they expand differently, which can cause a column, for example, to change position and alter the entire structure of the line, as it causes them to move.
Rodríguez Ramírez pointed out that the builders must participate from the conception and design of the work and carry out a work of supervision of topography, welding, have the columns plumb, “be in continuous contact with the designers, geotechnicians and geologists for any change or doubt ”.
For all these reasons, he expressed, “the project for line 12 is a disgrace for Mexican engineering” and I regret that today, with its exceptions, “researchers and designers are far from real field problems; the officials give priority to the political aspect and the builders have become financial ”.
Despite this, he assured, engineering must change, “even give it a new definition in accordance with new approaches and discoveries, so that, in this new era, we can find harmony in our projects and constructions in the rhythm of nature.”