An analysis of communications between Madrid’s Atocha control centre and the drivers involved in Wednesday’s collision near Urda, Toledo, points to failures that extend beyond the operator’s mistake. Specialists, including train drivers, say the recordings reveal uncertainty over the procedures to follow after a failure in the LZB signalling system, as well as weaknesses in the wider safety system.
The LZB system continuously sends driving information to the train, including the target distance, speed limit and braking curve. When communication is interrupted for more than six seconds, the railway switches to a backup arrangement known as BSL, under which drivers follow conventional trackside signals. ASFA provides an additional safeguard and should trigger emergency braking if a train passes a signal ordering it to stop.
According to the experts consulted, the AVE driver reported a partial transmission failure, but the Atocha operator issued the “LZB4” telephone instruction instead of “LZB3”. The latter would have required the train to continue under the BSL system and proceed at sight, allowing the driver to react to an obstacle or a visible stop signal. In this case, that would have meant a maximum speed of 40 kilometres per hour.
The LZB4 instruction ordered the system to be disconnected and reconnected before continuing under BSL conditions set by the control centre. However, the train resumed at normal speed, rather than at sight, even though another train occupied the relevant section of track. The initial estimate from the Independent Authority for the Technical Investigation of Accidents put the AVE’s speed at between 160 and 200 kilometres per hour when it struck the stationary Iryo train.
The recordings reportedly show the Atocha operator consulting documentation and other staff before deciding which instruction to give. Specialists view that hesitation as evidence of a training deficit. They also point to the absence of a final control mechanism that could have blocked or challenged the order, since the track section had not been cleared for normal running.
Transport Minister Óscar Puente has said the control screen showing whether another train occupied the track was working and displayed a red indication. The recordings show the Iryo driver telling Atocha at 8:41 that the train was stopped at the entrance to Urda. In a second call, she reported that it remained stationary because the system could not be restarted.
Experts say trains stopping temporarily on the track is common and does not normally represent a risk. What is highly unusual is for one train to collide with another. They add that the control centre should know the location of every train and should see an occupied section marked in red, although the images from the control screen have not been made public.
The LZB system, introduced on Spain’s Madrid-Seville high-speed line in the 1990s, has experienced other communication failures, according to drivers consulted by the newspaper. They reject, however, the idea that such incidents are either insignificant or so frequent that they should be accepted without concern. More recent systems such as ETCS provide continuous supervision of speed, braking and radio communications, but they are more expensive and are installed on several other Spanish routes rather than throughout the Madrid-Seville line.
The recordings also capture the AVE operator questioning the instruction to resume at normal speed. After repeating the other commands as required, the driver asks, “Normal running?” before accepting the order. For the experts, that exchange reinforces the impression that the immediate error occurred within a broader chain of procedural and organisational weaknesses.
Sources: El País Portada.