How to Reduce Track Damage & Derailment Risk

Australian Railways’ Weakest Link:

How to Reduce Track Damage & Derailment Risk

Mounting Pressure on Australia’s Rail Network:
Driven by massive ore extraction industries, rail has provided the critical transit arteries for Australia’s booming mineral export industries. In 2004/05 alone, the rail industry contributed $11.19 billion in value to Australia’s economy[1].

Yet while attention has turned to the prospects of a high-speed rail corridor for the eastern seaboard, bulk and heavy haul freight still constitutes the most significant net tonne-kilometre contributor to the country’s rail network – accounting for no less than 89% of total rail freight task. And there is still room for substantial growth: by 2014/15, industry estimates project an annual increase of 52.9% in the nation’s rail freight task, or 283.8 tonne-kilometres[2].

The benefits of the boom have, however, come at great cost to rail infrastructure. Bulk freight loads, overloaded by massive iron ore, coal and container transit loads, have exacerbated rail wear and fatigue, leading to a rise in track-failure incidents and a significant reduction in the lifespan of rail infrastructure.

Breaking Point – What Happens When Tracks Aren’t Maintained?
Poorly maintained tracks and surface topographies are a serious risk to safe and reliable rail transport. At best, it can exacerbate service delays or interruptions and damage trains, carriages and cargoes; at worst, overstressed rail infrastructure can trigger full-scale derailment, long-term service downtime, significant asset repair/replacement costs and, potentially, loss of life.

Between 2001 and 2009, Australian railways experienced 73 major derailments; of these, 52% were freight and 14% heavy haul.

Leading Track-Borne Causes of Derailment:
Rolling Contact Fatigue (RCF): Results from repeated overstressing of surface or subsurface material by millions of intense wheel-rail contact cycles. In the eight years from 1995-2002, RCF was strongly implicated in 122 derailments worldwide (potentially contributing to 160 more), including the 2000 Hatfield (UK) disaster, which claimed 4 lives and injured over 70[3].

In 2013 alone, RCF was implicated in several freight derailments on Australian lines, including the Xstrata/Aurizon Zinc derailment, with conservative estimates indicating a several million dollar clean-up and repair bill[4].

Track Misalignment: A multifactor phenomenon resulting from poor track maintenance and improper track conditioning. Key contributors to misalignment are track disturbance from resurfacing, ballasting, cleaning and resleepering, and insufficient anchoring of tracks during construction or maintenance.

Track misalignment was a major contributor to the 2006 Yerong Creek freight derailment, causing extensive damage to the main line and crossing points (700 metres of total track), the destruction of 8 freight-bearing wagons, and a 48-hour line closure.

Rail Buckling: Caused principally by a discrepancy between the optimal Design Neural Temperature (DNT) and the rails’ neural temperature (RNT) due to longitudinal movement of the rail – often referred to as ‘creep’[5]. It is crucial that RNT is at or near DNT to provide necessary leeway for dynamic traffic loads and lateral track stability.

Techniques for monitoring thermal discrepancies in the track are notoriously difficult to employ. As such, track creep remains a significant risk to rail freight in Australia’s harsh rural climates.

The Costs of Track Wear & Maintenance:
Due to constant rail-wheel interaction, rail wear and rolling contact fatigue (RCF), track degradation is inevitable. Yet with increasingly massive freight loads, the stresses on rail infrastructure have risen exponentially.

RCF alone costs European railways around 300 million Euros (AUD$485 million) per year in maintenance costs. The total cost of all defects amounts to 2 billion Euros (AUD$3.23 billion) per year[6].

The Office for Research and Experiments (ORE) of the International Union of Railways (UIC) notes that increased maintenance costs (60-65%) directly correlate with an increase in traffic, train speed and axel load. These costs are even greater when the quality of the track is poor.

Prevent Rail Disasters With ‘Vehicle Condition Monitoring’ Technology:
TechRentals, the southern hemisphere’s largest rental supplier of test and measurement instruments, has developed a breakthrough condition monitoring system (CMS) that pinpoints the precise location of track abnormalities.

Requiring minimal in-vehicle installation, the GPS coordinated measurements of the CMS device measures the lateral and vertical acceleration experienced by railway vehicles. These unique track coordinates are then outputted to Google Earth’s 3D mapping platform, allowing rail technicians to compare the performance of different rail vehicles across the same section of track.

This pioneering technology not only enables track faults to be immediately identified, but allows for vehicle performance, speed and freight loads to be evaluated on a comparative basis. By minimising latent track stresses, and maximizing track handling capacities, CMS can lead to a drastic reduction in the incidence of catastrophic track failure.

Downloadable Version (pdf)

[1] Australasian Railway Association, 2005, 2006; Australian Transport Statistics 2007.
[2] Australian rail transport facts, Apelbaum, 2007.
[3] Control of Rolling Contact Fatigue of Rails, Centre for Surface Transportation Technology 2004.
[4} Mining Australia “Xstrata train derails”, 2013 http://www.miningaustralia.com.au/news/xstrata-train-derails
[5] Track Stability and Buckling - Rail Stress Management, Ole, 2008 (http://eprints.usq.edu.au/6174/1/Ole_2008.pdf)
[6] Rail Grinding Best Practices and Condition Monitoring Acceptance System, Chattopadhyay