Is the Maya train on shaky ground?

The Maya train, which covers a 1,554km route on the Yucatán peninsula, is President Andrés Manuel López Obrador's flagship project to revitalize Mexico's southeast region. 

But construction began in 2020 without all the necessary environmental studies in place, drawing criticism from the opposition and activists, who focused on section 5 south, a stretch running between Playa del Carmen and Tulum whose route was changed in 2022. As a result, it plowed through pristine jungle and impacted the region's unique underwater cave systems. 

Critics claim the stretch of the railway represents a risk not just for the environment but also for riders. 

BNamericas speaks with engineer Víctor Hugo Martínez Rendón, who worked as an independent technical advisor on the Maya train's section 5, who warns of the danger of collapse. 

BNamericas: What has happened to section 5 south of the Maya train?

Martínez: Section 5 of the Maya train originally went from Cancún to Tulum. However, due to a construction strategy, it was divided into section 5 north, which runs Cancún to Playa del Carmen, and section 5 south, which goes from Playa del Carmen to Tulum.

Section 5 north is already in operation, it's 44km long and some faults are being corrected during the operating stage. Section 5 south has a length of 64-68km. It's still not known exactly because the sections can vary. Essentially, section 5 south underwent a change: It was decided to direct it through virgin jungle with pristine forests near Playa del Carmen, and that's where the problems have begun.

BNamericas: What kind of problems were caused by the change?

Martínez: With regard to the social aspect, there were land ownership problems, but I would like to focus on the technical aspects. In engineering works, it's always very worrying to build on karst soils. They represent a high risk because the problem comes from the bottom up.

The works that are based on these soils are a challenge. In this case, we're talking about a high-risk karst area, according to studies. There are also other areas of the section where it's not just the ground, but the domes [of caves], especially where the cenotes are already open and collapsed. The domes are less than three meters thick, so they have no load capacity to support a train.

That's why they decided to solve the problem with piles that are 25m deep, but that's very risky because perhaps where they detected stable ground at 25m, 10m away the stable ground might be 70m deep, but only 25m piles are being used.

BNamericas: What do you propose for this problem?

Martínez: With a group of scientists, I'm requesting that more in-depth geotechnical studies be carried out to find out exactly what the stratigraphic profile is along which the line passes in order to identify the foundation required and avoid a collapse when the line is operating. It's essential to conduct other detailed studies before going ahead with the 25m pile solution.

BNamericas: How likely do you think a collapse would be?

Martínez: These soils are very special. However, we need to know the stratigraphic profile – which I haven't seen since this work began – to be able to issue a technical opinion, particularly because it involves works that have a high social impact.

BNamericas: So, do you think that all the preconstruction studies that should have been done weren't carried out?

Martínez: Maybe they were, but I haven't seen them. A presentation was made to the president where a general explained that at 25m they had found stable soil with load capacity, but I think we need the profiles at a deeper depth and to cover the entire section because the ground they're talking about is semi-stable but that can change over time. On the section where there are studies, in the original design that was close to highway 307, it was shown that there were stable soils at different levels at depths of 20-45m.

BNamericas: Why was it decided to change that section?

Martínez: The decision was made between January and February 2022. At first it was claimed to be at the request of the hotel owners, to avoid problems with the train construction works. Later it was said that it was a strategy to give the landowners access to sell their products in the jungle. 

However, that hasn't been proven because the train stations don't pass through these areas, so the reasons for such a harmful change are unknown. It greatly affects the aquifer and especially the flora and fauna.

BNamericas: How serious is the environmental damage from the route change?

Martínez: A virgin forest has been lost, with many species that were even listed as being at risk of extinction, or rare and threatened. This is an ecocide that could have been avoided if the works had been carried out along the original lines.

BNamericas: The Maya train will also have freight trains. Do you think that could be risky with the karst soils?

Martínez: I think it will be a high risk. In the construction industry we always have to evaluate three very important aspects according to a planning program: economic viability, technical feasibility and the third, and which I consider most important, the risk analysis study. In the case of section 5 south, I don't believe that these aspects have been considered and that's why the cost has skyrocketed. 

The line has been changed with the lack of a defined project. I hope that the work can be suspended as soon as possible until we have the complete executive project and the studies: both the geotechnical studies and on the structure for the lines, and we can guarantee the safety of the project with a risk analysis study. I haven't seen any for section 5 south.

BNamericas: How much have the costs increased due to the lack of planning?

Martínez: The costs have skyrocketed because building next to a road isn't the same as building in the jungle where we don't know what we're going to find. That's why you must first have a technical feasibility project and there was none here.

They say that the initial work cost 120bn pesos [US$7.2bn] and now we're at 500bn pesos, and the project isn't finished yet.

The figure would have to be revised, but it's a matter of national security and we won't be allowed to know that until 2027.

BNamericas: Do the work involve any other risks?

Martínez: There are other risks such as derailments, like the one that occurred on March 25. They said it was due to human error, but we took a tour and realized something very important. My experience in the construction of railway tracks has shown me that the ballast layer has the important function of supporting and uniformly distributing the weight of the train, preventing the tracks from deforming, in addition to absorbing the vibrations caused by movement of the trains. Therefore, the structural stones to form the ballast layer must fully comply with the NOM-003-ARTF-2019 standard approved and published by this government in the official gazette.

I wanted the staff of Tren Maya to authorize me to take some samples, which was impossible. They said they were already conducting an internal investigation and couldn't allow us to do any tests on the quality of the ballast. They also didn't allow us to see the fastening screws to see if they met the load resistance. But I do consider that the ballast needs to be checked: The deformation that was shown in the photos on the left side of the track is a classic deformation with a subsidence in the ballast. For the safety of all passengers, I hope they comply.

BNamericas: Have you submitted the request to suspend activities to the authorities?

Martínez: It's still being prepared. They told us that we have to wait for the investigation they're going to carry out. It's a technical opinion.

BNamericas: Why do you think the warnings haven't been heeded?

Martínez: In the case of section 5 south, it was warned for years that it couldn't be built in the jungle. The corresponding study was delivered to Fonatur, to the presidency, but I think it was a political decision more than anything. They set the deadlines and moved forward without projects and without authorizations. It had to be fulfilled for the sake of fulfillment.

BNamericas: Would it be possible to mitigate the risk of collapse with maintenance?

Martínez: No, not at all. A geotechnical study has to be carried out before testing the trains. Once it's built there's no way to correct it. The ideal thing to do would be to suspend the works. I think that due to the time left, it will be very difficult for the Maya train to be 100% completed in this six-year government term [which ends on October 1], so we must think without pressure, to carry out the work that needs to be done, applying rules and procedures to avoid unfortunate consequences.