Report of a fire in a heavy goods vehicle on Rv 7 in the Måbø tunnel 19 May 2016
Road traffic report 2017/07
The Accident Investigation Board Norway (AIBN) has investigated a fire in a heavy goods vehicle that consisted of a truck and semitrailer, custom built for transport of heavy machinery. As a result of the fire, the Måbø tunnel sustained great damage and remained closed for a certain period of time. No individuals sustained any serious injuries as a result of the incident.
The heavy goods vehicle, that was approximately two years old and was transporting an excavator, had a a total weight of 71 tonnes and was issued an exemption from weight requirements. After having driven the ascent up Måbødalen valley and approximately 410 metres inside the Måbø tunnel, the driver of the heavy goods vehicle noticed smoke and flames coming from the right side of the front of the vehicle. The driver stopped the vehicle and went outside, but it was not possible for the driver to extinguish the fire with the available extinguishing equipment. An escort vehicle that was driving in front of the heavy goods vehicle picked up the driver, and they drove out of the tunnel whilst notifying emergency services about the incident.
The investigation has shown that the fire most probably started when a leakage arose in hydraulic hoses that were operating the steering system of the semitrailer, and that were exposed to rubbing over time. Hydraulic oil under high pressure sprayed onto hot surfaces of the exhaust system, which ignited the oil.
The hydraulic system was installed by a hydraulic system supplier, but the hydraulic system was not intended to operate the steering system while driving. This was not pointed out in connection with the approval and registration of the heavy goods vehicle.
Maintenance of the hydraulic system was not included in the service plan. The wear on the hydraulic hoses was neither detected during public controls of the vehicle.
The AIBN has issued three safety recommendations in connection with the investigation.
Safety recommendation
Safety recommendation ROAD No 2017/14T
The investigation into the heavy goods vehicle fire in the Måbø tunnel on 19 May 2016 has shown that a leakage arose in the hydraulic system that was installed in close proximity to hot surfaces and was not adequately shielded. High pressure in combination with damages on hydraulic hoses caused by rubbing was the probable cause of the fire. The investigation has shown that safety in connection with approval and use is not adequately addressed in the current rules and regulations.
The Accident Investigation Board Norway recommends that the Norwegian Public Roads Administration review and improve its procedures for the approval of vehicles with hydraulic systems that are active during driving.
Safety recommendation ROAD No 2017/15T
The investigation into the heavy goods vehicle fire in the Måbø tunnel on 19 May 2016 has found that a service plan for the hydraulic system was not included in the vehicle delivery, and that the vehicle owner neither had established an internal maintenance system for the hydraulic system. The AIBN believes that the heavy goods vehicle importer should have routines that communicate potential service requirements relating to the hydraulic system for the delivery of new vehicles.
The Accident Investigation Board Norway recommends that the heavy goods vehicle importer, as a complete supplier, ensure that service requirements relating to hydraulic systems also are communicated to the customer.
Safety recommendation ROAD No 2017/16T
The investigation into the heavy goods vehicle fire in the Måbø tunnel on 19 May 2016 has found damage from wear as far in as the steel braiding of two hydraulics hoses in the heavy goods vehicle that were used to control the wheels of the trailer. The leakage could probably have been prevented if the damage to the hydraulic hoses had been subject to inspection and/or visual inspection.
The Accident Investigation Board Norway recommends that the Norwegian Public Roads Administration incorporate the inspection of hydraulic systems that are active during driving in their inspection procedures.
Facts
| Location | RV7, the Måbø tunnel, Eidfjord, Hordaland county |
| Occurrence date | 19.05.2016 |
| Accident type | Fire in vehicle |
| Road class | National road |
| County | Hordaland |
| Police Disctrict | Hordaland |
| Vehicle type | Truck and trailer |
| Type of Transportation | Freight transport |
| Road region | Western Region |
| Accident category | Ulykke i tunnel |