Report on railway accident with freight car set that rolled uncontrolledly from Alnabru to Sydhavna on 24 March 2010

The accident was triggered by a misunderstanding between the local traffic controller and the shunter about which shunting route to set, and the result was that the freight car set started rolling from an arrival track (A track) at Alnabru. When the shunter added an extra freight car to the freight car set, the local traffic controller was convinced that the freight car set was being shunted for loading.

The result of this was that the local traffic controller released the mechanical brake that held the freight car set in place on the A track. The shunter had not intended to move the freight car set and had uncoupled the shunting engine.

There were no shared mental models, standard phrases or readback-hearback systems in place to prevent misunderstandings of communication between the local traffic controller and shunting personnel at Alnabru. Furthermore, two provisions which could potentially have stopped that particular chain of events were 'dormant' and not known to the operating personnel.

When it became clear that the freight car set had started rolling and was not coupled to a locomotive, it had already moved to track G4. It was not possible to stop the freight car set by setting a diversion route before it left Alnabru. Nor were there any barriers on the freight train track between Alnabru and Loenga/Sydhavna which could stop the freight car set in a controlled way. The accident reflects a breach of the ‘no single point of failure’ principle which dictates that railway operations shall be planned, organised and performed in such a way that a single failure does not lead to loss of human life or serious personal injury.

In the AIBN's view, the basic premise that allowed the accident to happen was the fact that Alnabru was being used in a manner for which it was not originally intended.This was a consequence of structural changes and increased rail freight traffic, combined with a lack of remodelling and development work on the infrastructure to reflect this development.

A focus on efficiency and productivity on worn-out, outdated infrastructure, and an insufficient focus on updating safe work practices had reduced safety margins. Political priorities and the NNRA's own prioritising of freight traffic had played their part in this lack of alteration or development.

The investigation showed that both the NNRA and CargoNet AS have consistently failed to handle safety-critical information in a systematic way. There was not enough of a culture of reporting incidents, governing documents were inadequately distributed and implemented, risk assessments were fragmented and inadequate, and the system for collecting and handling safety-critical information from the operational parts of the organisations was deficient. The result of this was that, until the time of the accident, the NNRA and CargoNet AS were both unaware that Alnabru had fundamental faults and deficiencies in terms of operational and technical safety barriers.

The NNRA had not adequately followed up its responsibilities as Principal Enterprise for infrastructure management, for instance through carrying our overall risk assessments. In a complex system like Alnabru, it is especially important that all the organisations involved work together to set up barriers against single failures. This does not seem to have been properly addressed. Alnabru lacked an overall safety management system which would pick up the risks that were a consequence of the many changes that had taken place over time.

The AIBN's investigation has shown that Alnabru does not seem to have been sufficiently 'seen' by the Norwegian Railway Authority (NRA). Even if the responsibility for safety lies with the railway undertakings, the AIBN would nevertheless like to see the supervisory authority playing a more proactive role in overseeing how the undertakings address this responsibility. This is particularly
important as regards control of the risk of major accidents in complex areas.