Sometimes we learn about fatigue the hard way. On October 17th 2000 it took 4 dead and over 70 injured persons to learn that maintenance is not just some annoying expense. On that day near Hatfield a train derailed due to rails that failed and fragmented. The cause of failure was rolling contact fatigue.
This blog post is not a technical article about rolling contact fatigue but an article about awareness.
Fatigue cracks initiate and then grow until a critical size of the crack is reached. From that moment on failure of the structure may occur. This process often takes a long time; months, years or even decades.
Although fatigue life in practice shows a lot of scatter, we do have the means to establish how long it will take until a crack size will be critical. Life estimations are based on analysis, experiments and field data (feedback from operation). Fatigue life estimation is not an exact science. There are many parameters influencing the life that cannot be quantified easily. To understand life estimations and to be aware of those influences you need at least some knowledge of fatigue.
Once a fatigue life analysis is done, the results need to be implemented. In case of rails that means inspection schemes and replacement times are determined. This is part of the maintenance process. Next step is that you actually perform that maintenance.
Since the fatigue process does take very long it seems easy to forget about it. This is a trap many engineering and maintenance managers have fallen into. They just score by “saving” money and leave the problems to their successors, or even worse, to victims of accidents. Let us have a look to a citation in the final investigation report  where the Zone Quality Standards Manager said in an interview after the crash, “I do not have knowledge of railway engineering nor railway safety”, which was completely contrary to the written requirements (“excellent knowledge of railway engineering safety and contractual matters”) for the role. The guy was probably good in budget cutting. This quote is symptomatic for the attitude towards maintenance that still exists in many organisations.
Did we learn from Hatfield? Hardly. We still get into problems due to lack of maintenance. That leads either to accidents (Ponte Morandi, Genoa) or economical damage (A1 Rhine bridge near Leverkusen, Merwede bridge) much larger than the earlier “savings”.
Maintenance is meant to avoid potential problems. To avoid potential problems you need to be aware of them. To be aware about potential problems like fatigue you need to have at least some basic knowledge about those problems.
 Train Derailment at Hatfield: A Final Report by the Independent Investigation Board. July 2006.
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