Today, rail networks across Europe are getting busier, with trains travelling at higher speeds and carrying more passengers and heavier axle loads than ever before. The combination of these factors has put considerable pressure on the existing infrastructure, leading to increased demands in inspection and maintenance of rail assets. The expenditure for inspection and maintenance has grown steadily over the last few years without however being followed by a significant improvement in the industry's safety records. As a direct consequence the immediate key challenges faced by the rail industry are: a) the improvement in the safety of the railway systems of EU member states, b) the development of new railways to accommodate the continued growth in demand, and c) contributing to a more sustainable railway, in both environmental and financial terms, by delivering further efficiencies and exploiting technological innovation.

Although, severe rail accidents are relatively rare within the EU, they do occur. Classification of rail accidents depends on their cause, which can be either a human error or equipment failure. A large number of all rail accidents are equipment-related, whilst a significant proportion of these are due to failed train wheels and axles. The continuous increase in train operating speeds means that catastrophic failure of a wheel or axle may result in very serious derailments, such as the one that took place in Eschede, Germany in 1998. This heavy rail accident caused loss of life, injuries, severe disruption in the operation of the network, damage to the tracks, unnecessary costs, and loss of confidence in rail transport by the general public. In the Eschede accident (Figure 1), a single failed wheel initiated a chain of events that led to the severe derailment of a high-speed train on the route from Munich to Hamburg, causing the death of more than 100 passengers and the severe injury of many others. Although axle failures have been rarer than wheel failures, there seems to be an increase in their frequency over the last few years, mainly attributed to the higher axle loads involved. Figure 2 shows an axle from a freight train that failed resulting in the death of one person and the injury of several others (Rickerscote, UK in 1996).

Figure 1: Photograph showing what was left of the Intercity Express high-speed train
involved in the Eschede accident (Germany) in 1998. Of the 287 passengers in the
train at the time of the accident, 101 died and 88 were severely injured.

Figure 2: Broken axle from the freight wagon involved in the accident
at Rickerscote, UK in 1996.