Research into railway track stability to improve transport efficiency and cost-efficiency

Fields of Research

  • 09 - Engineering

Socio-Economic Objectives

  • 88 - Transport


  • Railways
  • Geotechnical engineering
  • Ballast

UN Sustainable Development Goals

  • 8 - Decent work and economic growth
  • 9 - Industry, innovation and infrastructure
  • 11 - Sustainable cities and communities


Impact Summary

Over the past twenty years, UOW research has generated industrial benefits in the area of modern railway geomechanics, including: (a) Ballast gradation research for Rail Tracks, which led to improved Australian standards in ballast gradations, allowing greater loads to be carried at increased speeds; and (b) Enhanced track stability research, using geosynthetics, which enabled track stability improvements and increased the accuracy of rail track predictions at Bulli and Sandgate by 5-10%. This directly benefited rail asset owners, such as RailCorp (now Sydney Trains) and Australian Rail Track Corp, working to enhance the quality of the composite track structure, and the national economy by enabling more efficient heavy-haul networks, with increased speed and axle loads.

Related United Nations Sustainable Development Goals:

8. Decent work and economic growth
9. Industry, innovation and infrastructure
11. Sustainable cities and communities

Read details of the impact in full

Details of the Impact

The lack of sound knowledge to enhance rail track performance and reduce repair cost has been a major concern in rail practices worldwide. In NSW alone, replenishing ballast costs about $15M/year, and the loss in productivity by closing lines to replace ballast and related maintenance can cost three-fold higher. The loss of track geometry and instability associated with heavy-haul are primarily attributed to ballast densification and degradation. This can cause differential settlement, lateral movement and impeded drainage owing to crushed grains compacting over time and reducing the porosity. Over the past twenty years, research at the Centre for Geomechanics and Railway Engineering (CGRE) led by Distinguished Prof Indraratna and his team has led to the implementation of innovative research-based solutions in the area of modern railway geomechanics.

New Ballast Gradation

Ballast specifications in Australia remained unchanged for decades, except for subtle shifts to the British Standards. Due to recent increased axle loads, exacerbated foundation degradation and track misalignments have significantly compromised safety and increased maintenance costs. Ground conditions in Australia differ greatly to other countries, and no ballast design in the world takes into account the rate and extent of particle breakage. CGRE demonstrated – for the first time – the vital relationship between the track confining pressure and particle deformation and degradation using unique Experimental Modelling [1] & [2].

As a result of CGRE collaborations with RailCorp (now Sydney Trains) and Australian Rail Track Corporation (ARTC), Australian rail practices now take particle breakage, caused by train passage, into account when developing new ballast gradations [7] & [8]. Through the use of the new ballast gradation at Bulli (NSW) rail track, track longevity was increased by five to six years before maintenance was required. These outcomes directly minimise transport infrastructure upgrading and maintenance costs, while increasing the productivity of Australia’s mining and agriculture industries that rely on a fast and efficient rail network.

David Christie, Senior Geotechnical Adviser (2003-08), Rail Infrastructure Corporation wrote: “The new gradations for ballast and the logic for its transformation from current Australian standards (AS 2758.7:2015) are vividly explained in Buddhima’s Book – Advanced Rail Geotechnology-Ballasted Track. I am aware that Australia and several other countries including UK and India have now adopted these concepts. Recently, Ballast Breakage Index and Void contamination Index have also been adopted through American Society for Testing Materials (ASTM, STO 1605) since February 2018 after ASTM forum in New Orleans.”

In a landmark gesture, the NSW Premier and Transport Minister awarded CGRE a grant of $10 million for rail research in July 2009, further highlighting the importance of this research for Australian rail.

Use of Geosynthetics to Enhance Track Stability

CGRE research suggested that degraded, used aggregates (i.e. material recycled from RailCorp spoil tips) – strengthened by artificial plastic grids and energy-absorbing mats – would prove an economic and viable solution to enhance track stability. This novel solution was enthusiastically taken up and adopted by the rail industry.

Part of a new track at Bulli (NSW), constructed in 2012 using this method, proved to be more resilient for bearing greater trainloads with less settlement. The track was tested over a two-year period as part of a RailCorp-CGRE collaboration. David Christie (Rail Infrastructure Corporation), noted that the partnership “resulted in the construction of instrumented sections of track at Bulli and Singleton which have used these research deliverables to demonstrate the effectiveness of modern track sub structure design”. This technique also offered a practical option for reducing the need to quarry fresh ballast, thereby reducing environmental degradation while saving millions of dollars for the Australian rail industry.

This contribution was reflected in a 2009 Business-Higher Education Round Table (BHERT) Award sponsored by the Australian Commonwealth for “Best Research and Development Collaboration” for rail track innovations, which was presented to Prof Indraratna. The award was open to any field of study where innovative R&D outcomes demonstrated substantial community benefit, and was assessed by a judging panel of senior executives from higher education and business.

Moreover, a research innovation proposed by Prof Indraratna to use energy-absorbing rubber sheets in railway tracks was trialed on a heavy-haul track in Singleton near Newcastle during 2013-14. The concept was based on the idea that the kinetic energy of fast-moving trains transmitted to tracks would be absorbed by the SEAL (Synthetic Energy Absorbing Layer), thereby minimising the damage to track components, including a reduction in ballast degradation, which was proven through field monitoring over one year [3].

To mitigate the instability of tracks built on soft clay, original theoretical and numerical developments were instrumental in the design and construction of the Sandgate Rail Track in 2007 [9] & [4]. The research, assessing “Cyclic Excess Pore Pressure Development” with subsurface drainage was a world first [5] & [6] and as a consultant to Arup, CGRE was able to provide a priori prediction of the settlement and pore pressures of the Sandgate rail track within 5-10% accuracy [4].

In collaboration with key transport organisations, CGRE – under the leadership of Prof Indraratna – was awarded the 2011 Engineers Australia Transport Medal and 2015 RTSA Individual Award of the Railway Technical Society of Australasia (RTSA), the highest honour for rail professionals in Australia and New Zealand.


  • Sydney Trains (formerly RailCorp)
  • Australian Rail Track Corporation (ARTC)
  • Rail passengers
  • Rail freight companies
  • Australian mining industry
  • Australian agriculture industry
  • Environment (reduction in quarrying)


Impacted Countries
  • Australia

Approach to Impact

Summary of the approaches to impact

Our approach to impact in Engineering at UOW is characterised by a long-term commitment to research excellence, close collaboration with industry and the implementation of practical, innovative, research-based solutions. Our partnerships are supported by long-term internal funding schemes, investment in critical infrastructure and facilities, and strategic research initiatives tailored specifically to enhance Australian industry outcomes. Our research partners are our primary beneficiaries, with benefits rapidly extending to industry at large, government bodies and the community. Our research has encouraged industry to embrace frontier technologies through using new materials, innovative design and construction techniques, and advanced manufacturing processes.

Read the full approach to impact

Approach to Impact

Our research at UOW spans wide-ranging industry applications across twelve disciplines of engineering that are facilitated through our major applied research centres.

The Centre for Geomechanics and Railway Engineering (CGRE) illustrates our broad approach to impact, which is replicated across our applied research centres in Engineering. CGRE was established at UOW under the leadership of Professor Buddhima Indraratna more than a decade ago as a result of several ARC-funded geotechnical and rail track projects. CGRE has continued to prosper through numerous external grants (ARC DP and Linkage, CRC for Rail Manufacturing), and is one of the three nodes forming the ARC Centre of Excellence for Geotechnical Sciences and Engineering.

Our university and faculty funding enables our researchers to develop projects with potential impact into scalable, long-term solutions for our research partners. Initially, the CGRE was modestly supported by an internal budget of $50,000/year, plus approximately $200,000/year in external income. Through proactive team efforts and the unreserved support of UOW, CGRE has now grown to attract an average annual budget exceeding $2.5M.

We further support emerging areas of research-impact by investing in the equipment, infrastructure and facilities needed to deliver innovations that directly benefit industry. We provide internal funding support (e.g. PhD scholarships, performance funding, Infrastructure Development), cutting-edge testing facilities, and dedicated technical staff, specially trained in laboratory and fieldwork at all nodes, to support the team. CGRE is well equipped with seven state-of-the-art testing laboratories that service the rail industry and form an integral part of our SMART Infrastructure Facility, which now houses a specialised high bay railway laboratory. CGRE researchers have been consistently supported with UOW-funded travel grants for staff and students, research partnership grants and equipment grants.

This stable funding source has enabled CGRE to collaborate in an agile and extensive manner with the rail engineering community, at both the academic and end-user levels. Collaborators include other universities and Australian Rail Industry partners such as Sydney Trains, Australian Rail Track Corporation Ltd. (ARTC) and Aurizon. All of these agencies interface with industry groups and local communities. Through ongoing research in enhancing track performance, CGRE rapidly translates technical and scientific research into implementable solutions for end-users. This provides a unique service for end-users to access cutting-edge instruments and techniques, and technical expertise, for immediate application.

Our ability to deliver research with immediate translational benefits encourages strong support and investment from our research partners. CGRE’s research was crucial for initiating a $10M grant from RailCorp in 2009 for rail research, and the ARC has recently contributed over $4M of grants for the National Facility for High Speed Rail Testing and associated industry Linkage projects. Two European firms (Rhomberg and Getzner) committed over $60,000/year for 3 years, for a key project examining track performance in relation to the use of shockmats for attenuating impact loads. Metro Trains Melbourne (MTM) also contributed $50,000 towards track-testing facilities and instrumentation. CGRE developed a reputation as Australia’s ‘go-to’ centre for Transport Geotechnics, making it a key partner of the ARC Centre of Excellence in Geotechnical Science & Engineering (ARC-CGSE), together with its geotechnical counterparts at UWA and UoN.

CGRE impact on industry during the reference period has been significant, particularly in the revision of existing Australian standards for the placement densities and size gradation of rail ballast (AS 2758.7), geotechnical site investigation (AS 1726) and the formulation of new Australian standards (e.g. AS8700: Execution of Prefabricated Vertical Drains).

Our long- and short-term impact on industry is mediated through the specialist training of high-calibre engineers. PhD students (many with UOW-supported tuition and scholarships), as well as undergraduate and UOW-funded visiting students, have been critical for delivering immediate value to industry research partners. They also have strengthened the talent pool, with long-term and sustained benefit for Australian engineering. From 2011-16, UOW 09 disciplines have completed supervision of over 300 PhD graduates (21 in CGRE), and mentored over 60 postdoctoral fellows through national competitive grants and UOW fellowships (10 in CGRE, through ARC, CRC-Rail and Endeavour schemes). Many of our students have won national or international awards and our past students are now among CEOs and Principals of geotechnical Australian firms, e.g. Geoff McIntosh, CEO, Douglas Partners.

Engineering research pioneered at UOW is clearly valued by industry, as reflected by recent high-level consulting assignments, advisory and expert missions with research institutions and industry organisations – including the design and performance analysis of road embankments and railways, harbour reclamation, low-lying floodplain development and failure interpretation. Our research contributions have made strong impacts on Australian industry projects including the Port Kembla Outer Harbour extension, Sandgate Rail Project, and Surat Basin Railroad Project.

Our communication strategy targets key, influential members of industry – in particular designers, construction companies, manufacturers, regulatory authorities, and researchers in the wider community. Research outcomes are published in consultation with our partner organisations, with due consideration for commercially sensitive information. We also run professional development seminars, webinars, workshops, and meetings with international experts via web conferencing.

Associated Research

Since the mid-1990s, CGRE has led rail track research funded by grants from the ARC and the CRC-rail collaboration between UOW, RailCorp (formerly RIC), ARTC and Aurizon (formerly Queensland Rail). UOW has been instrumental in forming rail research teams in the area of track modernisation. UOW researchers have proudly developed one of the world’s best track testing laboratories with the close cooperation of RailCorp colleagues. Some large-scale equipment such as the Process Simulation Testing Chamber designed by Prof Indraratna and his team was fabricated at the RailCorp workshop under the guidance of former Senior Geotechnical Advisor David Christie. This equipment is the only one of its kind in the world that can simulate track conditions with train speeds of up to 300 km/hour.

The inception and success of the first CRC in Rail Engineering (2000-07) and the subsequent CRC for Rail Innovation (2007-14) were strongly influenced by collaborations between UOW and RailCorp. Several other organisations became partners on research projects, including companies in the services and supply chain of the rail industry. For example, a previous UOW-RailCorp project on track lifecycle analysis conducted under the guidance of Indraratna and Christie involved two Ground Penetration Radar (GPR) companies and two Geosynthetic suppliers, along with other major rail organisations including Queensland Rail and ARTC.


1. Indraratna, B., Salim, W. and Rujikiatkamjorn, C. (2011). Advanced Rail Geotechnology - Ballasted Track, CRC Press/Balkema (UK), 432p. Hard Cover.
2. Lackenby, J., Indraratna, B and McDowel, G. (2007). The Role of Confining Pressure on Cyclic Triaxial Behaviour of Ballast. Geotechnique, Institution of Civil Engineers, UK 57(6). 527-536
3. Indraratna, B., Nimbalkar, S. and Neville, T. (2013). Performance Assessment of Reinforced Ballasted Rail Track, Ground Improvement, 167(1), 24.34. Thomas Telford award, Inst. of Civil Engineers, UK
4. Indraratna, B., Rujikiatkamjorn, C., Adams, M. & Ewers, B., (2010). Class A prediction of the behaviour of soft estuarine soil foundation stabilised by short vertical drains beneath a rail track. J. of Geotech. & Geo-environ. Eng., ASCE 136(5), 686-696
5. Indraratna, B., Attya, A., and Rujikiatkamjorn, C. (2009). Experimental Investigation on effectiveness of a vertical drain under cyclic loads. Journal of Geotechnical & Geoenvironmental. Engineering, ASCE, 135(6), 835-839
6. Ni, J., Indraratna, B., Geng, X. Y. Carter, J. P. and Rujikiatkamjorn C. (2013). Radial consolidation of soft soil under cyclic loads, Computers and Geotechnics, 50 (1), 1–5
7. Australian Standards, (2015), Aggregates and rock for engineering purposes, Part 7: Railway ballast AS 2758.7:2015, 13p
8. Transport for NSW, 2015, Engineering Specification-Track Ballast (SPC 241), Transport for NSW, 8p
9. Adam, M and Ewers, B. (2008), The Design of Railway Formations for the Sandgate Rail Grade Separation, Australian Geomechanics, Vol 43 No 3, 33-42