The Railway Infrastructure Administrator is exploring, together with the National Geographic Institute, a new formula to detect earthquakes with a magnitude greater than 5.0 degrees on the Richter scale. It does so by taking advantage of the optical fiber installed in its infrastructure for the conventional and high-speed network through which Spanish trains circulate, once the needs of rail operation have been met. In this way, the IGN is studying whether it is feasible to apply DAS (Distributed Acoustic Sensing) technology to the fiber that Adif has deployed throughout Spain.
The National Seismic Network, belonging to the IGN, with whom Adif entered into a collaboration agreement in 2022 for this type of technical studies, is part of a project that performs detection using fiber systems to elucidate what a global monitoring system based on in DAS technology to apply in seismology.
In this pilot, Adif has made available to the National Seismic Network a 30-kilometer stretch of fiber optic installed between Soto del Real (Madrid) and Segovia, on the Madrid-Valladolid high-speed line. In this section, the infrastructure circulates under the central mountain range through the Guadarrama tunnels, the longest in the Spanish network until the Pajares (Asturias) tunnels come into service.
Thus, the fiber has become a dense network of sensors distributed every 20 meters that, by comparing the signals detected by these sensors with the seismic catalog, check if it is capable of detecting earthquakes of magnitude greater than 5 degrees anywhere. from the earth. The data set that will be obtained will be stored in a public repository to be used by the scientific community.
A technology with great potential
Adif and IGN have already tested this technology on the high-speed line between Antequera and Granada. There, 3,000 horizontal sensors distributed every 10 meters along 35 kilometers were installed. Then, the functional test was carried out to verify the feasibility of using fiber optics for these purposes and the advantages of incorporating this recording into earthquake detection and location tasks were analyzed.
The great spatial coverage and ease of use are the main advantages of this new technique, which with a single piece of equipment can have thousands of sensors distributed over tens of kilometers, making use of an existing network. In addition, this DAS technology can be extended to other railway uses, such as to detect landslides that affect the infrastructure and which is already being tested on a section of the Manresa-Terrassa line, in Catalonia.
Today, the Adif and Adif AV fiber optic network exceeds 24,000 kilometers in length, with great capillarity throughout the Spanish geography and which is interconnected with the networks of France and Portugal. It supports railway operation, but it also allows the implementation of the latest technologies, such as the ERTMS signaling system or the GMS-R mobile communications model.
Fiber optics as a way to obtain benefits
Such is the importance of this infrastructure, that the railway manager considered in 2021 looking for a business partner that could make use of the so-called dark fiber, that optical fiber installed but not in use, and which represented a very new line of business. attractive for Adif. But for this it required certain commercial and operational development that could not be carried out without expert partners in that area.
For this reason, it launched a public consultation to the market to find out the interest of the ‘telecos’ in exploiting it in certain key matters for the digitization of the Spanish economy, such as the arrival of 5G in rural areas. Adif’s fiber optic network is ceded until 2034 to Reintel, a subsidiary of Red Eléctrica, which holds the rights to use and manage the exploitation of 16,386 kilometers of fiber.
Added to this are another 6,130 kilometers, plus another 7,800 kilometers that either have entered into operation or are expected to be in operation before 2024, and which belong exclusively to Adif and Adif AV. The new investment vehicle with which the public company intended to exploit its telecommunications would have about 16,000 kilometers, to which many others would be added that will revert to the State in the next decade.
