Report on fire in tank trailer in the Skatestraum tunnel in Sogn og Fjordane county 15 July 2015
English translation is now available. On 15 July 2015 16,500 liters of petrol caught fire inside the Skatestraum tunnel in Sogn og Fjordane, after a tank trailer broke loose from the truck and ran into the tunnel wall., The tank got perforated in the crash, and fuel leaked out. AIBN's investigation shows that the trailer drawbar broke due to internal corrosion in the drawbar rods. The investigation has revealed weaknesses in the tunnel's ability to resist the spread of fire which spread over nearly 500 meters and escalated very quickly. It was only a very short window of time available for evacuation. Security Follow-up of the tunnel was after AIBN's assessment not satisfactory. Risk analyses had not described any measures that could handle such a situation. AIBN recommends the introduction of restrictions on the transport of dangerous goods based on a risk assessment of each individual tunnel.
The trailer broke loose from the tank truck and drove into the tunnel wall, and the front tank chamber got perforated. This caused petrol to leak out and run nearly 500 meters down towards the lowest point of the tunnel. The petrol ignited probably by heat/ignitions from the engine in a recreational vehicle that stopped close to the trailer.
The fire in the petrol that had spread on the road surface and the tunnel drainage system escalated rapidly. There was an intence fire which melted holes in all fuelchambers and the tanktrailer incinerated completely.
The truck driver drove out of the tunnel after having notified the VTS and oncoming cars. Several cars that followed the heavy goods vehicle into the tunnel managed to turn around and drive out the same way as they entered. No one was seriously injured in the fire, due to rapid and proper response from all road users who were in the situation.
The drawbar broke because it was greatly weakened by corrosion. The corrotion was detected four years earlier, and a repair that followed was not performed according to the trailer manufacturer's specifications. The same trailer was subjected to a total of eight new official inspections after this repair. NPRA has after the event focused on the verification and repair routines of drawbars. AIBN expects this issue to be followed up.
The investigation has also revealed weaknesses in the tunnel design and the ability to resist the spread of such fires. The steep gradient in the tunnel helped the fire spread over a wide road surface area and the tunnel’s drain system was not designed to handle the amount of petrol that leaked out.
It is revealed that the tunnel owner in its risk analysis before and after the occure did not disclose any measures to deal with such a scenario. Nor is it subsequently carried out or planned any new measures that could handle a new kind of event. AIBN considers that the safety monitoring of the tunnel has been unsatisfactory.
The fire escalated so quickly and sparked so much energy that it was a very short window of time available for evacuation. AIBN therefore recommends the introduction of restrictions on the transport of dangerous goods based on a risk assessment of each individual tunnel.
The animation shows the sequence of events and the AIBN's conclusions.
Safety recommendation ROAD No 2016/13T
Like most other tunnels in Norway, the Skatestraum tunnel has a drainage system designed in accordance with the NPRA’s manual on road tunnels. The gradient of 10% inside the tunnel combined with the fact that the drainage system was unable to drain away the liquid from the roadway surface, caused the petrol that leaked out to quickly cover a wide area, which in turn generated strong heat and a lot of smoke and explains the intensity of the fire on 15 July 2015. In order to prevent the spread of dangerous spills from vehicles and limit the size of the accident site, the tunnels’ wastewater drainage systems should be designed with a greater capacity for draining away large spills of dangerous liquids and prevent them from spreading at an early stage.
The AIBN recommends that the NPRA revise its requirements for tunnel drainage systems, so that they are designed to handle large spills of dangerous liquids carried by vehicles.
Safety recommendation ROAD No 2016/14T
The risk analyses for the Skatestraum tunnel carried out both before and after the fire on 15 July 2015 were not in accordance with the recommended guidelines in Manual V721 – Risk analyses related to road traffic, which require consideration or implementation of measures related to the most serious scenarios/incidents, regardless of the probability that they will occur. The AIBN is of the opinion that the risk analyses were inadequate with respect to the consideration of scenarios and risk-reducing measures. Inadequate risk analyses can entail that the damage potential and the unique features of each tunnel are inadequately assessed and addressed.
The AIBN recommends that Sogn og Fjordane county administration and the NPRA, when conducting risk analyses, describe and follow up measures related to the described scenarios/incidents.
Safety recommendation ROAD No 2016/15T
The investigation of the fire in the Skatestraum tunnel on 15 July 2015 showed that road users had a very short time window for evacuating the tunnel when the tank trailer broke loose from the truck. Road users responded rapidly and correctly when the incident occurred, but a minor change in circumstances could have had dramatic consequences. Because of the short time window and the extensive effect of a fire, the AIBN is of the opinion that consideration must be given to restricting the transportation of dangerous goods through the Skatestraum tunnel and similar tunnels.
The AIBN recommends that the relevant road authority together with the Directorate for Civil Protection and Emergency Planning introduce restrictions on the transportation of dangerous goods through tunnels, based on a risk assessment of each individual tunnel.
Safety recommendation ROAD No 2016/16T
The investigation of the fire in the Skatestraum tunnel on 15 July 2015 shows that the safety of this tunnel has not been adequately followed up by Sogn og Fjordane county administration. The risk analyses of the Skatestraum tunnel carried out both before and after the fire did not adequately address scenarios and measures. When the tunnel was restored after the fire, the capacity of the drainage system was not increased to prevent the spread of liquid over large areas. Nor have measures been considered or implemented to reduce potential consequences or restrict the transportation of dangerous goods.
The AIBN recommends that Sogn og Fjordane county administration review and strengthen its follow-up of safety in the Skatestraum tunnel and other similar tunnels on the county roads.
|Location||The Fv 616 road in Bremanger in Sogn og Fjordane county|
|Accident type||Fire in vehicle|
|Road class||County road|
|County||Sogn og Fjordane|
|Police Disctrict||Sogn og Fjordane|
|Vehicle type||Truck and trailer|
|Type of Transportation||Freight transport|
|Road region||Western Region|
|Accident category||Ulykke i tunnel|