Further inspection of switch structure
Implemented
Rail R
Accident
4.5.2011
B5/2009R/S292
Suosituksen perustelu
The investigation revealed that under test conditions it was possible to repeatedly create a situation in switch where mechanical oscillation in the closed blade caused the point switch to become unlocked. Previous research into the matter should be compared with the actual situation. It would also be advisable to study the other possible causes presented by VR Track Oy in its report. The infrastructure manager must determine whether the unlocking of switches due to mechanical oscillation is also possible in a switch that is adjusted according to reference values, as well as how small deviations from the reference values can cause switches to become unlocked. Additionally, it should also be determined whether current reference values should be changed. A risk assessment should be carried out on the basis of this information, and the necessary steps should be taken to reduce the potential risks.
Recommendation
How the mechanical switch lock become unlocked should be investigated under normal circumstances, as well as control disturbances in the point switches.
Toimenpide-ehdotukset
The investigation revealed that under test conditions it was possible to repeatedly create a situation in switch where mechanical oscillation in the closed blade caused the point switch to become unlocked. Previous research into the matter should be compared with the actual situation. It would also be advisable to study the other possible causes presented by VR Track Oy in its report. The infrastructure manager must determine whether the unlocking of switches due to mechanical oscillation is also possible in a switch that is adjusted according to reference values, as well as how small deviations from the reference values can cause switches to become unlocked. Additionally, it should also be determined whether current reference values should be changed. A risk assessment should be carried out on the basis of this information, and the necessary steps should be taken to reduce the potential risks.