By Paul Bladon, Partner, St George Consulting* and Chairman of RISSB’s Wheel Rail Interface Forum and Rail Turnouts Workshop.
RISSB’s goal is the enhancement of our industry’s safety, efficiency, productivity and performance, and with increasing demands being placed on rail transport this mandate is significant for all of our organisations.
This was first time that RISSB held a specific wheel rail interface forum and industry’s response was very encouraging with over 70 attendees, including track owners, rail operators, engineers, suppliers and academics.
Speakers over the three days included Stephen Marich, who was inducted in the International Heavy Haul Association Railway Hall of Fame in 2003; Dr Nannon Zong, the winner of the RTSA Wheel – Rail Interface 2013 Award for his outstanding PhD thesis on optimisation of rail joints and TasRail’s Chief Engineer, Robin Walpole, a railway infrastructure engineer with 35 years’ experience in operational, planning and consultancy roles throughout Australia and overseas.
A small sky scraper moving at 80km/h
The wheel and the rail are an integrated system and it is not possible to change one without affecting the other. Even though our respective roles often require us to consider the wheel and the rail separately, the more we as an industry understand the wheel rail interface holistically, the better our companies and business units will work together as well.
Here’s an analogy that focuses on the significance of wheel rail interface.
Consider a long heavy haul train in Australia. Loaded it can weigh about as much as a small sky scraper. Add up the contact areas between the wheels and the rail and this equals about one square metre – so that you have a small sky scraper balancing on one square meter traveling at 80km/h. Anywhere else in the world, other than a railway, this would be a bad thing. But this is what we do and the wheel rail interface is key to how we do it.
The forum highlighted that the wheel rail interface is a complex system and one that is subject to a range of stresses and variables. A common one being wheel creep and depending on the severity of creepage can cause flash temperatures at the interface over 800oC, heating in a microsecond and then similarly, rapid cooling.
Under extreme heat
My analogy here is that 800oC is in the temperature range of the Earth’s upper mantle, and the upper mantle is also referred to as the plastic mantle layer. So it is not surprising that under the more extreme shear stresses and temperatures possible at the wheel rail interface we can get plastification of the metal of both wheel and rail, as we are creating micro-environments not dissimilar to conditions found hundreds of kilometers beneath the surface of the earth. The wheel rail interface can be considered an extreme environment in its own right, particularly at the upper thresholds of what it is built to endure.
I draw these illustrative analogies not to over-simplify the engineering that we do, but to applaud it, because the forces at play are quite incredible and it’s why we gathered at the forum – to understand and be able to best manage this interface to increase our productivity, ensure the life of our assets is maintained and our operations are kept safe.
These goals were reinforced at the two day rail turnouts workshop which followed the forum. The workshop featured technical modules, interactive panel sessions and a site tour of Pacific National’s One Spot Facility at Kooragang.
Turnouts are a very complex area of trackwork and the two days covered a range of perspectives from design and manufacture through to signaling, bearers, lifecycle, and maintenance. Because of their complexity, turnouts require specialization in each of these areas and the workshop achieved its goal of better consolidating and sharing this knowledge across the industry.
With turnouts each part the world faces its own subset of issues we looked at topics and case studies relevant to the railway industry here in Australia such as those facing us concerning materials, multi gauge, rail joint insulation, and heavy axle loads on both light and heavy rail. The first day of the workshop focused on how the lifecycle of turnouts can be improved by better designs and products. These issues were expanded on the second day with discussions on maintenance priorities and concerns.
Thanks for everyone who participated over the three days in this unique opportunity to share experiences and learn from one another with the goal of improving our operations!
*Paul Bladon is a project manager with over sixteen years’ experience in the rail industry, primarily with projects related to wayside condition monitoring. Paul has worked with railways in Australia and North America that utilise TBOGI to improve the condition of their rolling stock and track and is currently a member of the organising committee for the RTSA Core 2014 conference.