The renewal of the signaling systems of the Madrid-Seville high-speed line was still unfinished when the Urda (Toledo) railway accident occurred, despite the fact that the Government had a modernization program endowed with 780 million euros and Adif had begun to put out to tender the actions on the safety installations in 2020.
So records El Periódico de la Ingeniería, which has detailed the scope of the planned work on the first Spanish high-speed line and the state of execution of its main components. The specialized publication points out that the European ERTMS level 2 system had still not replaced the LZB, the technology used since the inauguration of the infrastructure in 1992.
The comprehensive renewal program comprises 89 public contracts to work on viaducts, tunnels, track, electrification, telecommunications and safety systems. However, the existence of this financial allocation and of awarded contracts does not mean that all the work has been carried out or that the new equipment has entered into operation.
The published information does not allow establishing how much of the 780 million euros has actually been disbursed. What it does document is that the modernization of the signaling had been contracted years earlier and that, at the beginning of 2026, ERTMS level 2 was still officially under execution.
Adif put the signaling out to tender in 2020 for 131 million
The technological modernization of the Madrid-Seville line included the implementation of ERTMS level 2, the European standard for management and protection of railway traffic used in a large part of the Spanish high-speed network.
The project contemplated progressively replacing the LZB, keeping it operational during the transition to guarantee the continuity of commercial services.
According to the documentation gathered by El Periódico de la Ingeniería, Adif put out to tender in 2020 the package of safety installations for 131.1 million euros, with an initial execution period of 52 months.
The main contract was awarded in 2021 for 93.8 million, within a set of awards related to signaling, track circuits and turnouts that exceeded 136 million.
The implementation of ERTMS was to be developed in two phases: a first one between Madrid and Córdoba and a second one between Córdoba and Sevilla.
The works included new electronic interlockings, digital ASFA, object-fall detectors, modifications to the interlocking systems and adaptation of the control centers and telecommunications.
The project also contemplated maintaining the functionality of the LZB while the works were being carried out.
However, the initial execution deadline did not translate into the full commissioning of the new system. In January 2026, the Ministry of Transport was still identifying the implementation of ERTMS level 2 as a measure "in execution", according to the official documentation cited by the specialized publication.
ERTMS had not replaced the system installed in 1992
The Madrid-Sevilla line, 470.5 kilometers long, continued using the LZB, a railway protection system that transmits continuous information on operating conditions and supervises the train's speed.
This technology makes it possible to automatically order braking when certain safety parameters are not met.
ERTMS level 2, whose implementation was planned in the modernization program, also provides continuous supervision of speed and authorized movement, although through a more modern and interoperable technological architecture.
The renewal of the signaling had to be accompanied by the replacement of interlockings, the updating of detection systems and the adaptation of railway communications.
Nevertheless, ERTMS still did not constitute the main operating system of the Madrid-Sevilla when the Urda accident occurred.
The official information from the Atlantic Corridor, as detailed by El Periódico de la Ingeniería, differentiated a first phase of completed track renewal from a second still in progress, in addition to other pending infrastructure actions.
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What actions the 780 million program comprised
The modernization program for the Madrid-Sevilla was not limited to signaling. The allocation of 780 million corresponded to a set of interventions on different elements of the infrastructure.
Civil works contemplated waterproofing works on decks, repair of structural defects, adaptation of tunnels, stabilization of slopes, improvement of drainage, correction of settlements in embankments and conditioning of access roads and fences.
Also the nine viaducts of Sierra Morena were modernized and work was carried out on the maintenance bases.
In the railway superstructure, the Government counted at the beginning of 2026 the replacement of 111 high-speed switches and 24 expansion joints installed on viaducts.
Between 2022 and 2025, 71,000 sleepers had been renewed and a second phase was underway to replace another 123,000.
The renewal of the rail, however, did not consist of completely replacing the two track rails along the 470.5 kilometers. The contracts established selective actions according to inspections, wear measurements and the detection of defects.
Modernization also extended to electrification, with actions on catenary, electrical substations, power equipment and tunnel lighting.
In telecommunications, new fiber optic networks and the reinforcement and duplication of GSM-R were planned, used for communications between the trains and the command posts.
Therefore, the expression "comprehensive renewal" refers to the set of subsystems included in the program, not to the complete replacement of all the components of the line.
What is the ertms?
ERTMS (European Rail Traffic Management System) is a technological standard developed to improve safety and facilitate the movement of trains between European railway networks. Its main feature is the automatic supervision of speed and operating conditions, with the ability to intervene on braking if the train exceeds the authorized limits.
At its level 2, ERTMS uses radio communications between the train and a control center called RBC (Radio Block Centre). Based on the information received, the system continuously calculates and monitors the maximum permitted speed and the distance the convoy can travel safely. If the driver does not respond to a warning, the system can automatically activate the brakes.
Unlike LZB, a continuous supervision technology installed on the Madrid-Sevilla line since 1992, ERTMS is an interoperable European standard that facilitates the movement of trains equipped to use it on different networks. Both systems incorporate automatic protection mechanisms, so the replacement of LZB by ERTMS does not imply, by itself, that the previous system was unsafe.
The European Commission states that ERTMS promotes interoperability between countries and can improve the capacity of railway lines. Its level 2 allows movement authorizations to be transmitted directly to the cab, without necessarily depending on light signals along the track.
The failure of the LZB and the Urda accident
The situation of railway protection systems has acquired relevance after the collision between an AVE of Renfe and an Iryo train in Urda.
According to the information provided by Adif to RTVE and collected by El Periódico de la Ingeniería, the LZB was out of order and the trains were running using Lateral Signaling Block (BSL), with the ASFA as the onboard backup system.
This circumstance must be examined through the technical circulation records in order to establish the exact conditions under which both trains were operating.
The fact that ERTMS level 2 was not yet in service does not allow one to conclude that its implementation would necessarily have prevented the accident.
To determine this, it will be necessary to know the nature of the incident, the state of the interlockings and track circuits, the information available at the control center, and the orders transmitted to the drivers.
An announced investment does not equal an executed work
The information from El Periódico de la Ingeniería distinguishes three different phases: the awarding of the contracts, the material execution of the works, and the commissioning of the installations.
In railway safety systems, a finished work also requires tests, validations, and integration with the existing equipment before obtaining the necessary authorization for its operation.
For this reason, the 780 million associated with the modernization program do not, by themselves, allow the amount actually executed or the degree of commissioning of each action to be known.
To determine this, it would be necessary to examine the work certifications, the payments made, the reception files, and the corresponding authorizations.
The documentation analyzed by the specialized publication certifies that the program included important actions on the physical and technological infrastructure, but also that some remained pending.
In particular, the modernization of the signaling, tendered since 2020 and awarded in part in 2021, had not been completed with the full entry into service of ERTMS level 2.
At the time of the accident, renewed elements, previous equipment kept in operation, and next-generation systems still in the implementation phase coexisted. The investigation will have to determine the effective configuration of the installations and verify the functioning of the protections available during the circulation of both trains.