Report on derailment at Hovedbanen north of Bøn station 31 May 2016

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Description

31 May was the first hot day in 2016, which contributed to Green Cargo AB’s freight train 5242 derailing due to buckling of the track just north of Bøn station on the Hovedbanen line. The four rearmost wagons were completely or partly derailed. The section was closed for repairs for a total of four weeks.

The year before, Bane NOR SF had installed a cable duct at the derailment site for the level crossing protection system at Bøn station, next to the ballast shoulder. This may have contributed to weakening the lateral support in the curve where the buckling occurred. At the same time as the cabling project was carried out, vegetation was removed along the section, which led to increased sun exposure and may thereby have caused increased compressive forces on the continuously welded track. In connection with the buckling, there was also a track fault that had developed over time. The track fault had been registered in the last four measurements by the line measurement and inspection vehicle on the section (carried out during the period between May 2015 and April 2016), and the tendency was already present before the cable duct work started. In August 2015, at the same time as work was carried out, some track irregulatities on the section were reported.

The AIBN believes that the most important contributory causes to the derailment were as follows:
- Bane NOR did not have sufficient control of the compressive stresses on the tracks.
- Bane NOR had not corrected the track fault in time.
- The overall risk situation for the section was not sufficiently known and addressed in connection with the work carried out the previous autumn.

The AIBN submits two safety recommendations to Bane NOR SF as a result of this accident. One concerns the control mechanisms that are intended to ensure that track corrections are carried out and documented. In the other safety recommendation, the AIBN recommends that Bane NOR SF strengthen its process for ensuring a shared risk understanding at the interface between project-based work and day-to-day operations.

Photo: AIBN

Safety recommendation

Safety recommendation JB No 2017/03T

On 31 May 2016, Green Cargo AB’s freight train 5242 derailed due to buckling of the track just north of Bøn station on the Hovedbanen line. One of the factors that caused the buckling was a track fault that had developed over time. Bane NOR SF registered the track fault several times, but it was not repaired.

The Accident Investigation Board Norway recommends that the Norwegian Railway Authority request Bane NOR SF to review and improve the control mechanisms that are supposed to ensure that track corrections are carried out and documented.

Safety recommendation JB No 2017/04T

On 31 May 2016, Green Cargo AB’s freight train 5242 derailed due to buckling of the track just north of Bøn station on the Hovedbanen line. Work had been carried out on the section prior to the derailment. Bane NOR SF was unable to identify the risk factors that caused increased vulnerability to buckling, neither those that were known to the operating organisation nor those that were introduced through the work performed the year before.

The Accident Investigation Board Norway recommends that the Norwegian Railway Authority request Bane NOR SF to strengthen its process for ensuring a shared risk understanding at the interface between project-based work and day-to-day operations.

Location
Bøn station
Occurrence date
31.05.2016
Train No
4252
Type of Transportation
Freight train
Type of occurrence
Derailment
Rolling Stock
Freight wagon
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