Spain examines signalling and operational failures after high-speed train disaster

At least 69 people have been killed and more than 100 injured after two high-speed trains collided on the Madrid-Seville railway south of the Spanish capital, in the second fatal high-speed rail accident in Spain this year and the third deadly incident on the country's rail network.

The crash occurred on Wednesday 28 October near Urda in Toledo province after a Renfe train travelling south from Madrid struck the rear of a stationary Iryo service. The two trains were carrying a combined 544 passengers, with 393 aboard the Renfe service and 151 on the Iryo train. Two carriages derailed following the collision, with the Iryo train's rear cars falling down an embankment, leaving passengers trapped within the wreckage and prompting a major emergency response involving more than 500 personnel, helicopters, drones and heavy lifting equipment.

The developing investigation is focusing on the failure of the railway's LZB train control system and the decisions taken after automated protection became unavailable. According to preliminary information released by Spain's transport ministry, a computer-related failure at around 8:30am affected approximately 63 km of railway and automatically stopped six trains operating along the corridor.

LZB, or Linienzugbeeinflussung, continuously communicates movement and speed information between the railway infrastructure and trains. The system has been in service on the line since it opened in the 1990s and is due to be replaced by the more modern European ERTMS. When it became unavailable, ADIF, the state-owned company that manages Spain's railway infrastructure, took manual command of operations from the traffic control centre in Madrid.

The Renfe train involved in the collision was subsequently authorised to resume its journey even though the Iryo service remained stationary approximately 25 km ahead. Audio recordings reported by Spanish media appear to show controllers instructing the Renfe driver to reconnect the LZB equipment and then continue under lateral signalling at normal operating speed. The Iryo driver had twice informed the control centre that her train was stopped and that she could not restart the LZB, the second time at 8:48am, five minutes before the collision.

Spain's transport minister Oscar Puente said preliminary information indicated that a red signal had prohibited movement but that the train was nevertheless given permission to proceed without speed restrictions, following what he described as an erroneous order from a train controller and a decision made under inexplicable circumstances. The Renfe service ran at speed between 8:36am and 8:52am before striking the stationary train at 8:53am. AITAT, the independent body investigating the crash, estimates the impact speed at between 160 km/h and 200 km/h.

Under the procedures described following the accident, operation without the normal automatic protection system would ordinarily require significantly reduced speeds, potentially around 40 km/h where movement depends on the driver's line of sight. Investigators will therefore examine why the train was allowed to return to normal operating speed and whether signalling, communication or operational procedures failed during the transition to manual control.

No final cause has yet been established. AITAT said on Thursday that its investigation team had not yet been able to speak to those directly involved, including the drivers and rail traffic controllers, as they were not in a condition to be interviewed. Authorities are examining the computer malfunction, the functioning of the LZB system, communications between controllers and train drivers, the movement authorities issued after the failure and whether established degraded-mode procedures were followed correctly.

The collision has again placed Spain's high-speed railway network under intense scrutiny. In January, 46 people were killed near Adamuz in Andalucia, around 130 miles from Wednesday's crash and on the same Madrid-Seville route, when a break in the track caused an Iryo train to derail onto an adjacent line and collide with a Renfe service. Days later, a commuter train derailed near Barcelona during heavy rainfall, killing its driver.

Spain operates around 4,000 km of high-speed railway and has one of the largest networks of its kind in the world. Passenger use has also increased significantly in recent years, making the reliability of signalling, maintenance and operational fallback systems increasingly important as traffic levels grow. Before this year, EU statistics placed Spain's rail safety record among the best in Europe.

All high-speed services between Madrid, Ciudad Real and Andalucia were suspended following the latest crash while emergency teams worked at the site and investigators began gathering evidence. Spain has declared three days of national mourning as the identification of victims and examination of the wreckage continue.

The central technical question will now be why a signalling-system failure that initially stopped trains as a protective measure was followed by an operating decision that allowed one train to resume at high speed while another remained stationary on the same route. Establishing that sequence precisely will be essential before responsibility or the underlying cause of the disaster can be determined.