Transitioning from Reactive to Proactive
Track Management on Network Rail
July 30, 2004
Railways traditionally have relied
on reactive
measures to maintain the infrastructure. But in order to effectively
compete in today's
economic environment, they must move away from a "fix it
when you find something wrong" mentality toward predictive,
trend-based monitoring systems that enable them to identify and
correct emerging problems before they disrupt the network, Gary
Sanford, head of development and examination at Network Rail,
told delegates at Advanced Rail Management and Interface
Journal's 2004 Rail/Wheel Interface Seminar.
 Network
Rail (NR), the UK track authority, has begun charting such a
course, and has implemented a number of innovative approaches
to achieve condition- or trend-based monitoring and maintenance
planning. "We have the technology and the equipment," Sanford
said. "We now have to get at the hearts and minds to make
this happen."
NR (formerly Railtrack) undertook a comprehensive study of rolling
contact fatigue (rcf) after a broken rail was implicated in the
deadly Hatfield crash several years ago. Working with researchers
from around the world, NR identified three primary modes of rcf:
steady-state contact, which is found on tight curves; bi-stable
contact, found on medium curves; and convergent contact, found
on shallow curves and tangent track. In steady-state contact,
high stresses are generated by curving forces at the gauge corner
of the rail. There are high stresses in the gauge corner in bi-stable
contact, but there is also movement across the rail. Convergent
contact generates lateral rail misalignment and dynamic action
of the axles in opposite directions. This results in changes
in rolling radius and longitudinal forces, and shifts in the
contact patch.
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