KCPM Consulting has shown that current methods of assessing rail fatigue are deficient and can lead to costly, unexpected failure.

Fatigue of a rail is usually caused by millions of cycles of sudden, high-intensity tension stresses in the rail foot, due to the passage of millions of train wheels. If a fatigue crack occurs in the foot, it can rapidly propagate through the rail, leading to a rail break which can cause catastrophic train derailments.

Work by KCPM has shown that the usual method of predicting the maximum stress in the rail foot ignores critically important factors.

Firstly, the company has proven that those maximum stresses are in fact not predictable because they occur randomly in time and location along the rail. A new risk-based approach is needed.

Next, KPCM has identified that operational factors such as the mix of traffic, wheel maintenance policies and practices, and even train driver behaviour, can dramatically affect the size of those maximum stresses.

Traditional rail design and selection ignores all these issues which helps to explain why the occurrence of rail fatigue has been so hard to predict till now.