Ballast!! Who needs it?

David Christie

Rail track ballast is often ignored in the rush to deliver on rail upgrades with money going into more obvious tangible assets like sleepers, rails, fastenings, signalling, and “big yellow machines” etc. As has been witnessed lately with the problems of track geometry on the Main Southern Railway, the condition and depth of ballast is critical for the maintenance of a safe high speed track. You can’t blame the soil.
Rail Ballast is often forgotten and becomes part of the scenery in railway engineering. It is regarded as a GIVEN and it has been said “what more can you research about ballast?”

The behaviour and role of ballast is becoming more critical in order to maintain the tighter controls on track geometry required for higher speeds and increased track loading. There has been significant research into the behaviour of ballast and its response to the increased demands on rail transport with a better understanding as to how the track support reacts to the higher frequencies of loading imposed.

The presentation will review some of the history of ballast and its critical functions that are required for safe track and to introduce the recent research work of the University of Wollongong into understanding the expectations that have been placed on the performance of ballast. This research work has extended over about 15 years through the Cooperative Research Centre for Rail Innovation.

Some developments into track substructure analysis and design tools coming out of the work at the University of Wollongong from the CRC research will also be introduced.

Speaker biography

David has been a Principal Geotechnical Engineer for NSW rail authorities for 24 years. From 1994, he collaborated with the University of Wollongong with research of ballast behaviour funded through ARC grants.

In his role as Senior Geotechnical Adviser in RailCorp NSW from 2003 to 2009, he was the Project Manager of several research projects conducted by the Cooperative Research Centre for Rail through the University of Wollongong and Monash University. These projects address Ballast-Track-Formation interaction which included the study of the degradation behaviour of ballast, the effect of fouling on the permeability of ballast, and the analysis of the transfer of loads to the formation. He also coordinated RailCorp’s input into a research project conducted by Monash University for the stabilisation of problem soils using Lime-Fly ash injection methods.

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