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ARTC's Mr Wayne Potter (left), UniSA's Dr Don Cameron (middle) and
Rail CRC student Henry Mancini look over native vegetation samples.
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Vegetation has long been the enemy of the railways, however this
project is working to prove that identified and managed vegetation
can be beneficial to railway infrastructure. The overall goal of
the project is to develop a balanced ecological-engineering
approach to minimise maintenance associated with settlement of clay
soils along rail corridors, keeping in mind the need for weed
management and reduction of fire risk. Problems to be addressed
include:
- Excessive ballast usage.
- Continuous maintenance of track geometry.
- Ballast pocket formation due to softened and wet foundation soils.
- Poor drainage on track.
- Expansive clay soils in the subgrade formation.
- Softening of clay soils.
- Lack of vegetation in the corridor in terms of greenhouse benefits.
- Identification of appropriate species in the corridor, and
- Weed growth and over-excessive use of herbicides.
The project, and subsequent planting and growth of native
vegetation on rail corridors, has the potential to reduce the
annual cost of re-ballasting and fettling work undertaken by the
rail industry, which is estimated to be more than $10 million per
annum. In addition, other benefits include fewer delays due to
speed restrictions, fewer interruptions to trains due to track
closure and the reduced need for heavy machinery work seasonally to
utilise rail corridors as fire breaks, as a cold burn in winter
would suffice with planted native vegetation.
The project was independently assessed by STEM Partnerships in
2006, with the risk-free-value of the research estimated to be in
the order of $42.6 million over 30 years. Taking into account the
risks associated with the research, the expected value is $12.2
million. Some concerns were highlighted in relation to
industry’s impatience with the long lead time before the full
benefits and outcomes of the plantings can be realised.
Progress to date:
- Review of numerical and analytical models for the effects of soil
suction induced by vegetation on track stability.
- Preliminary FEM analysis and development of simple model to
simulate soil behaviour and suction effects around the root zones
of trees/shrubs.
- Geotechnical field test sites established, trial vegetation pilot
plots planted and monitored, soil samples tested and analysed.
- Last phase of greenhouse and field work experiments underway.
- Development of physical model for root water uptake rate completed.
- Ongoing development of statistical models for ecological
restoration.
- Preparation of
Fact Sheet #1 ‘Improving rail corridors by restoring native
vegetation’
completed and available on members only area of website.
Future outcomes:
- Development of predictive model to simulate effects of water
absorption by selected plantings and enhanced track stability.
- Guidelines, procedures, practices to improve track stability with
plantings of native vegetation.
- Adoption of research recommendations by industry.
Project Leader: Dr Don Cameron (University of South Australia)
Project Manager: Mr John Cowie (Australian Rail Track Corporation)
