SPAIN: A serious failure of communications is at the heart of early investigations into the fatal collision between two high speed trains at Urda near Toledo on October 28. Mike Bent analyses how the tragedy unfolded.
The 07.53 Madrid Atocha to Sevilla RENFE Viajeros AVE service, operated by Siemens Mobility Velaro trainset 103-206, was travelling at a speed in excess of 100 km/h when it struck the rear of the stationary 07.40 Madrid to Sevilla Iryo service, formed of a Hitachi Rail-built Series 109 ETR1000 trainset, near the village of Urda in Toledo province, 120 km from Madrid.
The rearmost three cars of the S109 were knocked down an embankment, while the leading car of the S103 was derailed, falling down the other side of the embankment. Three of the cars behind it were also derailed, but remained almost upright.
Onboard the S109 were 147 passengers, while the Renfe train was carrying 397. By mid-afternoon on October 28, the number of fatalities had risen to 64, with several passengers still unaccounted for. Initial; reports found that 40 of the victims were onboard the S109, with 24 on the S103 trainset.
The collision took place at 08.54, according to phone records of the national emergency number 112, although it could have occurred at any time between 08.48 and 08.54. At 09.10, infrastructure manager Adif Alta Velocidad ordered the closure of the Madrid – Córdoba/Sevilla high speed line, and all trains on it were halted. The province of Castilla-La Mancha declared a state of emergency at 09.15. Transport Minister Óscar Puente arrived at the control centre at Atocha at 09.40 to monitor the situation.
By 11.52, all the injured passengers that could be found had been evacuated. Rescue teams then started removing bodies from the trains. The number of dead increased during the afternoon. At 12.50, Adif AV confirmed that services on the Madrid to Toledo line were running normally, and that it was still possible to operate trains at the southern end of the Andalucía corridor between Málaga and Sevilla.
Train control renewal
Puente appeared before the media at 15.00, telling a press conference that the accident was ‘really inexplicable’. By that point, some substantive details of the collision were starting to emerge, even if the precise cause of the accident will be determined in the medium term by a formal accident investigation.
The Madrid to Sevilla line has two levels of Automatic Train Protection, the well-established LZB cab signalling technology widely used on the German network for many decades, and a back-up in ASFA Digital. Given these two layers of protection, the accident should never have occurred.
No fewer than 13 technical reports cited by investigative news agency Colpisa have revealed that since an initial investigation into the reliability of the LZB control equipment on the Andalucía high speed line prepared by consultancy Ineco in 2019, there has been a series of problems with the ageing ATP on this section.
On June 30 and July 12 2025, the ATP failed, and there was another failure on July 7 this year. Theft of cabling was suspected. The 2019 report recommended the replacement of the electronic interlocking system at the Urda refuge loops, together with the control equipment at nearby Mora and Los Yébenes. But it was feared that the integration of the latest train control technology into a signalling architecture which dated from the opening of the line in the early 1990s would affect the functionality of the older equipment.
Tendering complexity
In February 2020, Adif AV invited tenders for the renovation of the train control equipment between Madrid and Sevilla. One of the conditions was that the LZB equipment should continue in use after ETCS Level 2 had been installed and during the installation period. Subsequently, Adif AV reconsidered its plans, proposing that LZB should be removed once the ETCS had been commissioned.
This caused confusion among the bidders, who had already submitted their proposals, which had then been evaluated. Adif AV concluded that the only way forward was to relaunch tendering with amended specifications. The original tender was annulled in November 2020, which bidder Thales then protested. Following a hearing, the relaunched tender process saw Adif AV award Thales España a €93.9m, 52-month contract to renew the train control system. Under the plans, LZB would continue to be active while ERTMS was being installed.
This formed one of three contracts to address signalling along the line. These included one worth €21.6m for the renewal of track circuits, and the other worth €21m covered replacement of pointwork at various locations, including the points used to access the refuge loops at Urda and Mora. Thales would replace 1 306 ageing track circuits with ones which would enable the train protection system to continue functioning while the changeover from LZB to ERTMS took place.
Progress unclear
These contracts all formed part of a wider route modernisation on the Madrid – Sevilla route that was launched in the early 2020s at a cost exceeding €700m. In May 2024, the CNMC regulatory authority suggested that the ATP changeover would take place during 2025-26.
In March 2026, government sources stated that the installation of ERTMS was still in progress, but not where work was taking place or how far it had advanced. What is known is that during 2025, there were 162 different incidents on the line which resulted in trains being delayed. On four occasions, a blanket 200 km/h speed restriction was imposed on the whole line — the maximum speed on the route is 300 km/h.
Leaked audio controversy
The chain of events which led to the tragedy has been covered in detail in local media following a series of leaks of audio recordings relating to the operation of the section of line in question in the hours before and immediately after the crash.
The appearance of the leaked content in the media has been criticised by the railway unions, with the Secretary General of one of the largest, SEMAF, insisting that ‘we, as always, support an independent and rigorous investigation into the entire accident, and the causes will be determined by the investigation’. Diego Martín told EFE on October 29 that ‘what we have is the same information that has been leaked to the press’. He added that SEMAF ‘regrets the leak of information that should have been kept secure’.
According to to the documents released by Colpisa, the problems with the signalling appear to have started during the evening of the previous day. The driver of an AVE service heading from Madrid to Málaga reported that his train had been brought to a halt at Km 120 because it had failed to acknowledge the signals from the ATP transponders. The driver asked that his name not be revealed.
This seems to indicate that there was already a defect in the ATP systems. The chain of events on the morning of October 28 began at 08.30, when the LZB equipment failed over a 63 km stretch of the line, resulting in all six trains on that section coming to a halt. According to the leaked audio, at 08.36, the Atocha control centre informed the drivers of these trains that the fault had been rectified. Permission was given for all six trains to continue their journeys; the dispatcher communicating with the drivers was accompanied by an auxiliary staff member and a supervisor.
The following communication with the driver of the S103 service involved in the accident took place at 08.36:
Atocha: ‘Maquinista de tren 02080. Desconecte y vuelva a conectar y vuelva a conectar el LZB. Reanude marcha. Y luego reanude la marcha al amparo del BSL con marcha normal’. [‘Driver of train 02080. Disconnect [the LZB reception] and reconnect. Start the train, and continue, using BSL [in-track transponders], at normal speed.’
Driver: ‘Con marcha normal?’ [‘At normal speed?’]
Atocha: ‘Sí.’ [‘Yes.’]
As a result, the AVE service did resume its journey, and between 08.36 and 08.53 it accelerated to a speed likely to have been up to 200 km/h. Having covered approximately 25 km, the driver saw the Iryo trainset ahead, and applied the emergency brake, slowing the speed to around 100 km/h at the moment of impact. There was no further contact between the Atocha control centre and the driver, who was killed in the collision.
The Iryo question
A key question for the investigators will be to discover why the Iryo trainset had not moved once the apparent all-clear to move had been issued. There were two conversations between its driver and the Atocha control centre. The first was at 08.41, after the driver had received a similar message to that passed to the AVE driver, and the second followed a failed attempt to reboot and restart the LZB train protection equipment from the cab.
Iryo driver: ‘No me está permitiendo el tren reiniciar el sistema LZB, por eso estoy todavía detenida en la señal de entrada.’ [‘The train is unable to re-initiate LZB. Because of that I am stopped before the entry signal [to the refuge loops at Urda].’
Atocha control: ‘Cuando pueda, vale, y si tiene problemas, nos llama.’ [‘OK, when you can, and if you have any problems, contact us.’]
The traffic controller in Atocha then spoke to his colleagues: ‘El 6076 está teniendo problemas con el equipo… En Urda tenemos el problema.’ [‘Train 6076 is having problems with the [ATP] equipment…The problem is in Urda.’]
Seven minutes later, at 08.48, the driver contacted Atocha with the message, restating the train’s location, while stating a ‘loss of transmission operating with Bloqueo de Señalización Lateral’ (the BSL transponders that provide a final layer of train protection and location detection for trains in degraded operation).
Atocha then asked whether the train was stationary, and the driver confirmed this. The normal protocol following such an incident is that trains must then continue under line-of-sight provisions, as if there were no signals operating, at a speed of no more than 40 km/h, and be prepared to stop if another train or a signal at danger is seen ahead. It remains unclear why the control centre at Atocha did not inform the driver of the S103 that the Iryo train was still stranded at Urda, and therefore bring the Renfe train to a halt.
Casual language
The staff member in the control centre who had given the ‘right away’ to the stopped trains was subsequently interrogated by the Guardia Civil, the country’s quasi-judicial police force. By mid-evening on October 28, the data recorders of both trains were being investigated, and the recordings were being released to the media. What was evident is that the drivers were not ordered to continue under ‘marcha a la vista’ rules with the 40 km/h limit.
The language used in the calls was casual, and not a standard form of giving commands as is typically mandated in the aviation and shipping world, or on railway networks in other countries. This was in spite of actions taken by Adif in the recent past to tighten up on the training of control centre staff to avoid human error in critical communication.
In its 2025 annual report, the national safety authority Agencia Estatal de Seguridad Ferroviaria had noted ‘an increase in the number of collisions and derailments on account of weaknesses in the human factor of operations, in particular, since 2021. In 2023 four instances were noted, and in 2024, six’.
This was attributed to a range of factors, including staff being overloaded with work, a lack of refresher training to ensure staff competency was up to date in line with best practice, and a lack of investment in personnel training and automation tools. Particular emphasis was placed on the necessary authorisation given to drivers to pass signals in degraded operational circumstances, which requires a precise knowledge of conditions on the track to ensure that this is done safely. In many cases, simple visual inspection of the control centre information screens is insufficient.
Diversionary routes
Service recovery in the wake of the crash is being complicated by engineering works affecting the conventional main line between Madrid and Córdoba, where the section through the Despeñaperros pass is closed for gauge clearance works to support the launch of rolling motorway intermodal freight services.
Alternative routes are available via the two lines linking Madrid with Mérida, from where trains could be routed via Zafra to Los Rosales and Huelva.
Source: rg
