Management options for existing and new rail in tangent and shallow curves

Running surface cracking and spalling associated with squats or studs and consequent spalling damage in sections of ARTC track which is utilised by passenger and freight services has led to the need for replacement of a large amount of the most severely affected rail, and early re-railing for a substantial portion of the remainder. The affected track sections compromise tangent track or shallow curves in which the head hardened rail grade was used exclusively. A key issue leading to this damage was the long term deficit in rail grinding due to the expectation, based on experience in other rail operations, that head hardened rail required grinding 50-100% less often than standard carbon rail in equivalent locations. Maintenance strategies in these corridors also have to strike a balance between higher speed passenger and higher axle load freight operations. These provide a particular challenge in terms of determining which rail grade to use and the required grinding intervals, taking into consideration the constraints on track access windows in which maintenance can be scheduled. Whichever grade is used, factors such as the current and future traffic, including axle loads, annual haulage rates and the mix of freight vs passenger services has to be considered carefully. Maintenance constraints such as the available and planned capacity for grinding, and alternative rail maintenance strategies such as milling must also be considered in the grade selection process.