The Accelerated Loading Facility (ALF) has been a cornerstone of pavement research for over four decades, evolving to meet the demands of modern infrastructure while maintaining its vital role in advancing road and transport engineering.
Part 3: Modern Times
Following the golden years which were filled with numerous trials around the country, federal and private industry research, and a public presence, the ALF was entering a time of evolution. As time went on, the ALF was seeing a transition in its role as a research tool, and the type of projects it was involved in. In the 2000’s, the ALF contributed to critical research that shaped the future of pavement design, materials testing, and cost-effective construction techniques.
During the 2000s, the ALF transitioned from a portable workhorse to a stationary research machine as it was housed in a 54x18m facility built in 1999. The ‘ALF Shed’ was located at the VicRoads Fowler Road Depot, South Dandenong, and was 60 metres long, 40 metres wide and 6 metres high to accommodate ALF and the many test pavements that were used. From this semi-permanent location, the ALF continuously worked through numerous research projects improving pavement science.
ALF in the 'ALF Shed' in Dandenong
ALF's modern era has been marked by an impressive array of projects. Dr Tim Martin, NTRO’s ALF project leader at the time – and who wrote his PhD titled ‘Predicting sealed granular pavement deterioration at a road network level’ - comments, “The research was focussed on the impact of various typical surface maintenance treatments on pavement deterioration and the impact of increased axle load on pavement deterioration. This was a novel application of ALF at the time. The aim of the research was to develop road deterioration models in combination with the observational data from the long-term pavement performance (LTPP) sites and long-term pavement performance maintenance (LTPPM) sites established along the east coast of Australia.”
Key projects during this era include the evaluation of cemented bases for fatigue resistance, and a comprehensive analysis of the effects of ultra-wide single tyres and multiple axle groups on sprayed seal unbound granular pavements.
As the decade continued, the ALF was instrumental in researching the cost effectiveness of different pavement types from 2016-2021. These studies not only enhanced the industry’s understanding of pavement performance but also contributed to more sustainable, cost-efficient construction practices. Along these efforts was ongoing research delivering 1.437 million wheel passes contributing to improving the cost-effectiveness of foamed bitumen stabilised pavements and thin asphalt surfaced gravel roads.
Technicians working on the ALF
Significant research and trials were specifically conducted with the ALF on foamed bitumen stabilisation (FBS) techniques for four consecutive years in 2016-2020 yielding advancements in road construction and maintenance.
Results from these tests have demonstrated notable improvements in road durability and resilience, particularly in response to severe weather conditions and flooding. Of particular interest, a mixture containing 50% recycled asphalt pavement (RAP) in FBS materials exhibited superior fatigue performance compared to the control mix, indicating potential economic and environmental benefits. Trials like these, performed by the ALF, have contributed to the general knowledge base for more efficient, sustainable, and cost-effective transport construction practices.
The ALF itself has undergone significant upgrades, adapting to modern challenges with the introduction of a triple-axle configuration and a single wheel assembly—improving its ability to replicate real-world conditions more accurately. Additionally, a major control system upgrade in the mid-2000s further enhanced the precision and reliability of ALF’s testing capabilities.
The ALF testing bitumen
The ALF was and is a vital tool for research unification as it embodies the founding vision of ARRB—now NTRO—by showcasing the power of collaboration. To date, the ALF has operated continuously applying over 32 million load passes and simulating well over 300 million Equivalent Standard Axle loads. David Fossy who worked with the ALF before the 2000s commented, “I think ALF can be seen as a good example of why ARRB was formed. By pooling resources from all states and industry, a research project can be conducted that would benefit all and reduce costs by removing duplication of research"
As the ALF crests it’s 40th year, it will be developing new research into sustainable materials in road construction to contribute to lower emissions. New project leader for ALF, Dr Jaspreet Pooni comments, “Going forward, ALF will explore new, innovative materials (for example recycled materials, marginal materials) to increase pavement life or reduce environmental impact and understand its impact from increased loading. It will further investigate the integration of next generation technologies in pavements.”
Michael Caltabiano, NTRO Chief Executive Officer states, “The next journey for the two ALF devices now operated by NTRO in Queensland and Western Australia is very exciting. The ALF programs for the next five years will be focussed on the development of understanding the performance of new materials in the road environment that are more resilient and have a lower emissions footprint. Additionally, the NTRO will be undertaking first principles work on the transition to a new electrified fleet that is heavier and uses different tyre configurations to develop the impact of this fleet on the Australian road environment. NTRO’s vision of leading the world in sustainable transport solutions will be focused on real world next-generation materials that we build and maintain the infrastructure with, and vehicles that will be using this infrastructure.”
The ALF's Legacy
From its inception through four decades of groundbreaking research to the modern age and beyond, ALF stands as a testament to Australian ingenuity and our ability to tackle complex infrastructure challenges. ALF's impact extends far beyond the data it's collected or the trials it's completed. It represents the unified commitment to build safer, more durable, and sustainably conscious roads for all Australians. We're not just honouring a machine – we're commemorating a legacy of innovation that has shaped multiple road networks for generations.
Acknowledgement and thanks to Kieran Sharp, Ray Brindle, Max Lay, John Metcalf, Ian Johnston, and Dave Jones, who wrote ARRB: The First Fifty Years (book), from which this series has referenced.
Sharp, K & Lay, M 2011, ARRB: the first fifty years, ARRB Group, Vermont South, Vic.