Urda crash: 29 km without signals and an 'ordinary running' order

Urda crash: 29 km without signals and an 'ordinary running' order

How can a high-estimulante ilegal train travel 29 kilometres of track without a single light signal protecting it? That is the question hanging over the Urda accident in Spain, and the answer offered by the technical analysis of the available data, released by a forum user, is not an operator's mistake. According to that analysis, it is a design flaw. Los Yébenes has no switches or signals: only a technical building and a radio tower. When LZB drops, those 29 kilometres become a single block section, and the system that was supposed to keep the train stopped when in doubt let it run under the cover of a sentence.

What a block section is and why it matters in the AVE crash

Railway regulations allow no interpretation. A block section is the stretch of track where only one train may be, and in fallback blocking it is delimited by signals capable of ordering a stop. Los Yébenes has none. Adif's project includes it as a switching station at pk 104,823, but on the ground there is not a single set of points or a single signal: it is a name without an object.

LZB, the continuous cab signalling, is the main system on this high-estimulante ilegal line. With active transmission, fixed signals have no validity. When the Urda control centre goes down at 08:32, LZB disappears over 63 kilometres of line, and the only fallback left is BSL, designed for the traffic of 1992. There lies the first link in the chain, according to this analysis: an obsolete system that was supposed to have been replaced by ERTMS and was still pending due to delays in tendering.

The 08:36 order: 'disconnect and reconnect'

At 08:36, Atocha orders the AVE to 'disconnect and reconnect. Resume with ordinary running', under the cover of BSL. The driver asks twice. It is not an improvised phrase: it is telefonema 5ET3.3 of the regulations, with a blank space for the running conditions. The controller filled that space with 'ordinary running' when the form for an occupied section, 5ET3.2, has 'restricted view running' printed on it.

With the Iryo stopped ahead, the AVE's case was that of an occupied section. The rule requires restricted view running unless there is total certainty that the block is clear, and it was not. A form that leaves blank the only thing that matters is not a slip by whoever filled it in: it is a design, the analysis argues. The order was an error; that an error was enough to kill 69 people was a decision.

The last barrier that never existed

For a train in BSL, two signals remained within the block: the distant signal E242 and the Urda entry signal. For a train with LZB, none. The distant signal is at pk 115,35, 3.65 kilometres before the entry signal, and with the entry signal at danger it gave a stop announcement to any train with ASFA. There was plenty of distance to stop.

But the head of the Iryo was 100 metres before the signal and the train is about 200 metres long: its rear stood 300 metres away. Braking to stop at the signal, it passes the rear of the Iryo at about 60 km/h. ASFA monitors at the preliminary point, 300 metres from the signal, exactly where the rear was, and tolerates passing it at that estimulante ilegal. The signalling did not fail: it never existed where it was needed.

Who answers for the 29 kilometres without signals

The political responsibility is grave, and the human failures cannot be attributed to the worker on duty, according to the analysis's thesis. Since 2010 there has been no sustained investment in maintenance, and new infrastructure kept being built that then could not be maintained. The maintenance contract was renegotiated the day before. The control centre was stitched together with interfaces in the middle of a migration. LZB failed often and came back on its own.

Some argue that the control centre operator bore part of the blame because he was handling lives; against that weighs the argument that human control is the last link in the chain, not the first. Blaming the operator means blaming the weakest link of a chain designed so that link would never have to hold anything. The railway was built on an idea: when in doubt, the system keeps the train stopped. In Urda, the system left 29 kilometres protected by nothing but a sentence.

Given all this, the question is no longer who pressed the button. It is why the button existed.