Spain high-speed train crash: signalling vulnerabilities could be key to understanding the accident

A tragic accident on the high-speed train line between Andalusia and Madrid has exposed the urgent need to upgrade Spain’s railway system.

At 19:45 on Sunday January 18, a modern Iryo high-speed train collided with a Renfe train at the switch (turnout) leading into Adamuz station in Córdoba province, Andalusia. The Iryo 6189 service, travelling from Málaga to Madrid, had registered for the track change, but the current information is that the last three carriages literally jumped over the diverted switch that gives access to the track adjacent to the platform, leaving the main track clear.

This caused the last three carriages to derail and collide with the Renfe Alvia 2384 service, which was travelling in the opposite direction from Madrid to Huelva. The collision was violent, though the combined speed of the two trains is still unknown.

Rail liberalisation in Spain

The Spanish passenger rail market was opened up to new competitors in May 2021, but until early 2023 the only trains permitted to run on the Andalusia-Madrid corridor were those operated by the state-owned company Renfe. The reason was that the blocking and safety system on these tracks had not been updated.

Following pressure from new operators OUIGO (owned by French state-owned company SNCF) and Iryo (owned by Trenitalia and its Spanish partners AirNostrum and Globalia), which were already active on the Madrid-Barcelona and Madrid-Levante routes, the Andalusian route was opened up to competitors. This increased the frequency of services and expanded the choice available to users.

The high-speed line from Madrid to Andalusia was inaugurated in 1992, making it the oldest in Spain. Although it has been improved and upgraded in several areas, its safety systems are in urgent need of renovation.

Signalling systems

Across the EU’s nearly 227,000km of railway tracks, there more than 25 different, non-interoperable train protection and signalling systems. These systems (the German LZB, the French Crocodile, the Italian BACC, the Spanish Asra, and so on) control and enable the safe movement of trains.

The German LZB (Linienzugbeeinflussung) signalling system remains in operation on the Andalusia-Madrid railway corridor, installed for the high-speed line. Although efficient, this system is surpassed by the European Rail Traffic Management System (ERTMS), which is already installed on the newest lines.

The ERTMS specifications come from European Union Council Directive 96/48/EC. The aim is for this trans-European system to completely replace national systems and be fully deployed throughout the EU by 2050. The intermediate target is for it to be in use by 2030 on the 51,000km of train lines that make up the nine main corridors of Europe’s core rail network.

In Spain, the new ERTMS system currently exists alongside the old LZB system, which modern trains “read” with a technical workaround known as Specific Transmission Modules (STMs).

Possible causes of the accident

The causes of the accident are still unclear, but it is unlikely to be a fault with the train for several reasons: the trains involved are modern and new, with little wear and tear, and the last technical inspection of the Iryo 6189 train had been carried out four days earlier. Inspections cover many things, including the condition of the wheel flanges, possible stress fractures, the different types of brakes, and so on.

As far as we know, the infrastructure at the point of the accident is also new, meaning the track geometry (curves, straight sections, slopes, ramps) should be in perfect condition. This leaves the possibility that the switch point may not have functioned properly.

At all intermediate stations that are not high-capacity, there are passing tracks or sidings where trains can park and let other trains pass that may be coming behind them and not stopping at that station.

The Iryo train unit was changing tracks to park. One possible hypothesis is that the switch mechanism initially worked correctly due to the signal sent by the LZB reading STM system, but that, for some reason, the switch point moved to the “straight” position prematurely. This would have caused the right wheel of the Iryo unit to collide, jumping over to the adjacent track due to centrifugal force and speed, in the opposite direction to the switch, towards the Renfe unit, which was travelling in the opposite direction. The Renfe train was dragged from the cab down to a currently unknown number of carriages, as can be seen in the images released.

Another possibility is that there was an object on the track, but this would have caused the train to derail from the front.

A deteriorating network

Spain’s high-speed railways, once an emblem of reliability, modernity and vision for the future, have gradually deteriorated. Delays have gone from being rare and brief to lengthy, which has led Renfe to withdraw its commitment to punctuality and ticket refunds. Ongoing incidents affecting the infrastructure managed by the state-owned company ADIF – involving overhead lines, brakes and couplings (such as in the tunnel connecting Madrid’s Atocha and Chamartín stations) – have also undermined user confidence.

Additionally, political ups and downs have prevented the development of a single, agreed-upon plan for the viability, modernisation and structure of the network, which would provide a safe means of transport to meet the growing demand for rail services instead of air travel for distances of up to 800-1,000 kilometres.

The reality is that at this moment there are at least 39 dead, dozens injured and a starkly poor impression of the Spanish railway system. Political and technical leaders must take responsibility, regardless of their ideologies and survival strategies. At stake is a transport system used by a growing number of people in the business and tourism sectors alike, and a major component of the country’s infrastructure.

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Carlos Gutiérrez Hita receives funding from the Spanish Ministry of Science, Innovation and Universities, and from the Valencian regional Ministry of Education, Culture, Universities and Employment.