In this installment of the Circular Transformation series, Paula Honrado and Gonzalo Vicente, from the Environment, Quality and Energy Department, explain the concept of the circular economy as a model to keep natural resources within the production cycle.

Prioritizing materials with recycled content, working with local suppliers, and properly managing the waste we generate are key factors in reducing emissions.

In 2024, over 92% of the waste generated from Sacyr’s activities has been reused, recycled, or recovered. Since 2020, we have avoided emitting nearly 10,000 tons of CO2 and have recovered more than 23 million units of waste.

Gabriel Palacios Hernández
Prevention officer and Head of Drone Operations

Sacyr always strives to undertake our projects with prevention and safety as primary objectives. In pursuit of this improvement, we decided to become drone operators in February 2017, as we believed that the use of Remotely Piloted Aircraft Systems (RPAS) (more commonly known as drones) would yield significant benefits, providing greater agility and safety in fieldwork.

In addition to reducing risks in our sector, they also aid production, becoming smaller, more manageable, resistant to weather conditions, and equipped with features that make their flights more efficient and faster.

Drones have countless applications, with new ones emerging daily, but the challenge lies in discovering these uses because the technology is already here, waiting to be applied.

Infrastructure inspection

In infrastructure inspection, RPAS can perform reviews without requiring a worker to be suspended by a lifeline on a slope or in a basket beneath the deck of a bridge. The risks are substantially lower because the worker is not exposed, and work efficiency is much higher because the task is completed in less time.

The use of RPAS is now widespread in surveying, using photogrammetry to obtain 3D models of terrain and orthophotos, which are high-resolution photographs obtained from the combination of partial photos in which distances, areas, and volumes can be measured with great precision.

Replacing operators with RPAS in confined spaces, inspecting high-voltage towers or wind turbines, and using underwater RPAS for inspecting treatment plants or collectors are tasks already being performed, significantly reducing risks.

It is important to consider that drones have their own usage risks, which, thanks to aviation regulations and their high safety standards, are closely monitored to prevent, primarily, the uncontrolled fall of these devices on people or material goods.

Like any flying device, it is susceptible to ceasing flight in an unplanned manner, becoming a weight that, aided by the speed it acquires in the fall, can be fatal. The smallest professional drones weigh around one kilogram, so we can imagine what they can become in free fall.

Additionally, RPAS are devices with propellers, batteries that could ignite, and are powered by electricity in most cases. All of this can lead to accidents for the people who operate them.

Photogrammetry

In what activities can we use drones within our sector?

- Photogrammetry work for topographic surveying: Photogrammetry has transformed the way surveyors work. Instead of traversing the terrain to be "surveyed," obtaining the different points, now the drone performs that work for them. The arrival of drones with integrated RTK systems has further reduced the need for obtaining control points.
- Building inspection or construction monitoring: The activity of "construction monitoring" through aerial images and videos is increasingly in demand. It is the best viewpoint to see the progress of the work.
- Inspection of structures in civil works: If we use the drone to approach the structure to be inspected, being able to capture images or videos, we avoid placing the worker in those areas and the use of costly auxiliary means.
- High-altitude inspection of high-voltage towers: Traditionally, this activity has been carried out by the worker ascending the tower itself, from an aerial lift, or from a helicopter, which is positioned at the top.  Drones clearly avoid putting the worker at risk of falling from height and at risk of electrocution, among others, incorporating RGB cameras with powerful zooms or with thermographic cameras.
- Confined space inspection: There are already drones of minuscule dimensions that do not suffer damage during their impact in narrow areas, with high-quality television cameras, that can replace operators in these tasks.
 

ISABEL RUBIO ARROYO | Tungsteno

St. Peter's Basilica is not only the spiritual heart of Catholicism, but also a monument that encompasses centuries of art, architecture and mystery. From its origins in the time of Constantine to its underground nooks and passageways, this monumental temple continues to fascinate millions of faithful and visitors every year. Here are some of the most surprising and lesser-known facts about the world’s largest Christian church.

The history behind St. Peter's Basilica

The St. Peter's Basilica that we know today was not the first church to occupy this site. In the 4th century, Emperor Constantine commissioned a church to be built here, which stood for over a thousand years. However, it was not until 1506 that Pope Julius II decided to replace it with a new, monumental construction in tribute to the Apostle Peter, who is believed to have been buried on that very hill in the Vatican. Construction took almost 120 years and involved the participation of prominent Italian architects and artists such as Donato Bramante, Michelangelo and Raphael. While Bramante took inspiration from the Roman Pantheon for his initial design, Michelangelo was responsible for the iconic dome.

The imposing interior of St. Peter's Basilica. Credit: Fabbrica di San Pietro / St. Peter's Basilica

The largest Christian church in the world

This monumental work embodies the splendour of the Vatican. At 136.5 metres high, its dome is the tallest in the world. The interior covers more than 15,000 square metres and its total area extends to about 2.3 hectares. Recognised as a UNESCO World Heritage Site in 1984, it is considered the largest Christian church in the world.

View of the interior of the dome of St. Peter's Basilica. Credit: Fabbrica di San Pietro / St. Peter's Basilica

Saints welcome the faithful in the iconic St. Peter's Square

In front of the basilica, St. Peter's Square can host thousands of people. According to the Vatican's official website, Vatican News, more than 100,000 people attended Pope Leo XIV’s first greeting from the square. Designed by Gian Lorenzo Bernini, the square features an elliptical colonnade arranged in 284 columns in four rows, which symbolise the embrace of the Church. At its centre stands an Egyptian obelisk, flanked by two fountains. The square is adorned with statues of saints who welcome visitors and, according to the Vatican, represent the union between the heavenly and earthly churches.

St. Peter's Square and its iconic colonnade. Credit: Fabbrica di San Pietro / St. Peter's Basilica

The popes who rest beneath St. Peter's Basilica

Throughout history, St. Peter's Basilica has inspired numerous legends about hidden passageways and secret chambers beneath its structure. Beyond the myth, the truth is that there are several real underground spaces, such as the Vatican Grottoes and the Necropolis, which house ancient papal tombs. Although Pope Francis has chosen the Basilica of Saint Mary Major as his burial place, the remains of 91 popes lie beneath Saint Peter's. These papal tombs are located alongside those of members of royalty and nobility. Notable pontiffs buried here include emblematic figures such as Pius X and John Paul II. For archaeologists, this collection of tombs is a historical treasure of incalculable value.

The Vatican Necropolis. Credit: Fabbrica di San Pietro / St. Peter's Basilica

The Vatican's secret passageway

Very close to this monumental complex is the Corridor of Borgo, also known as the Passetto de Borgo, a fortified corridor connecting Vatican City with Castel Sant'Angelo. Although it doesn’t pass directly under the basilica, it forms part of the Vatican's defensive system and was constructed as an escape route for popes during times of crisis. The corridor’s most famous episode occurred during the Sack of Rome in 1527, when Pope Clement VII managed to escape through it and took refuge in the castle. According to Rome's Department of Major Events, Sports, Tourism and Fashion, “the Pope was saved by the skin of his teeth, running through the narrow corridor, while the courtiers and nobles who accompanied him protected him with a dark cloak to prevent his white robe from becoming an easy target.” Today, some sections of the Passetto can be visited on guided tours from Castel Sant'Angelo, revealing one of the most strategic and lesser-known corners of Vatican history.

View of the Passetto di Borgo from Castel Sant'Angelo in Rome. Credit: Rome's Department of Major Events, Sports, Tourism and Fashion

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