18 mars 2019

PROSE investigates and evaluates BVB unusual infrastructure damages

Basler Verkehrs-Betriebe (BVB) have optimized several processes in its technology management division and made changes to its organizational structure following the discovery made last summer of unusual damage on its tracks. This discovery showed a different, new damage pattern which can be attributed to a maintenance backlog in wheelset machining. The BVB Board of Directors wanted to understand the circumstances and causes as well as the administrative and personnel responsibilities that led to this maintenance backlog. The board therefore commissioned an independent external investigation for which the results are now available. 


The unusual track damage showed a new damage pattern and is attributable to the maintenance backlog in the area of wheelset machining. This had already been confirmed in August 2018 by internal investigations by BVB and by technical experts from PROSE AG. Maintenance intervals were disregarded, and correct gauge settings were missed. 


A task force on the subject has been organised during the first phase. PROSE also recommended short-term speed reduction measures – whilst launching an investigation to understand the safety relevance of each problem identified. PROSE found no operational risk from the maintenance backlog for BVB during the maintenance of the vehicle fleet so an immediate shut-down of tram operation in Basel was prevented. 


However, the extent of the effects of the maintenance backlog can be clearly seen at many points in the state of the infrastructure. The hollow run-out measurement not previously considered has proven to be particularly detrimental to the condition of the stock rail and, above all, the wing rail areas of the frogs. 


Corresponding recommendations were presented. Measures for root cause analysis were proposed, which primarily lead to a metallurgical investigation. 


Risk control measures were also proposed to allow further operation on the BVB network. If any new areas of damage are discovered, speed reduction can be proposed until the damage is removed. The general speed reduction already initiated by BVB is effective. 


There hasn’t been any extraordinary damage on the tracks anymore since the causes of this unusual damage was fixed during September 2018. The costs of repairing the damage amounted to around CHF 950,000. The company’s operation has also suffered as a result. “It was important to the Advisory Board that an independent external body investigated how this maintenance backlog could occur,” says Chairman of the Board Yvonne Hunkeler. Immediately after the causes became known, the management optimized various processes. “We regret that these losses have occurred and are at the same time convinced that we have taken all necessary steps with the adjustments made immediately,” says Director Erich Lagler.  


Follow-up projects were ordered based on the results of the investigation. A review of the transverse table with regards to the established findings has been made. Also, a metallurgical investigation has been carried out when it comes to rail gauge derogations. A hollow rail recommendation for a meter gauge railway has been given, which is the best practice in the industry for hollow rail definition. PROSE has carried out a reprofiling strategy – reviewing the reprofile strategy, findings and recommendations. 


Find out more about this project on the project factsheet.

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