Abstracts December 2010
Vol.19 No 4

Aquatic ecotoxicity of bitumen emulsions used in chip sealing

Paper 1

Philip Herrington, George Ball, David Bremner, Mike Martin and John Patrick

Referred Paper
This paper has been critically reviewed by at least two recognised experts in the field.
Originally submitted: November 2009.

The ecotoxicities of four representative New Zealand chip sealing bitumen emulsions were measured using a freshwater crustacean (Daphnia magna) and an algal species (Pseudokirchneriella subcapitata). The results are discussed in terms of the New Zealand Environmental Risk Management Authority (ERMA) classification system. On the basis of the tests carried out, it is predicted that
cationic bitumen emulsions used in chip sealing would fall under the ERMA classifications of either 9.1D (slightly harmful to the aquatic environment) or ‘not classified’.

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Methodology function using experimental laboratory data

Paper 2

Mofreh F Saleh

Refereed paper
This paper has been critically reviewed by at least two recognised experts in the field.
Originally submitted: March 2010.

In this paper, calibration and validation of the Shell fatigue performance function, which is currently adopted by the Austroads design guidelines, are carried out. Seventeen asphalt concrete beams of hot mix asphalt were made by a local contractor.  The asphalt mix is made of aggregate gradation of a maximum nominal size of 14 mm and a bitumen 60/70 penetration grade. Thirteen beams were tested for fatigue at a constant strain mode in the University of Canterbury, Department of Civil and Natural Resources Transportation laboratory, while the other four beams were tested by a local contractor laboratory. Asphalt beams were tested at different strain levels spanning a range from 300 me to 650 me. The measured fatigue values were compared with the Shell predicted fatigue values.
The Shell model consistently underestimated the fatigue life at all the tested strain levels.
The experimental data of the 13 beams tested at Canterbury Laboratory were used to determine a calibration factor for the Shell model in order to minimise the differences between the measured and the predicted fatigue data at all strain levels. A calibration factor was determined and incorporated in the Shell fatigue performance model so that a minimum total prediction error was obtained. The
calibration factor based on the tested beams was found to be in the order of 5.6824. Fatigue data for the other four beams were used to validate the calibrated Shell model. It was found that after calibration the Shell model closely matched the measured fatigue values.

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The proficiency of sand equivalent and methylene blue (clay index) test methods for determining the deleterious mineral content of weakly metamorphosed sedimentary rock

Paper 3

Jason S. Lowe, Douglas J. Wilson and Philippa M. Black

Refereed paper
This paper has been critically reviewed by at least two recognised experts in the field.
Originally submitted: July 2010

Weakly metamorphosed sedimentary rocks have the potential to contain levels of deleterious minerals that can have a negative impact on aggregate properties. Two of the most frequently employed methods to determine the cleanliness and therefore ensure suitability for use of fine aggregates and sands are the sand equivalent and methylene blue tests.

Values relating to these test methods are often adopted in specifications as pass/fail criteria for establishing the suitability of an aggregate. This approach means many aggregate sources are precluded from use, and so a primary aim of this research is to highlight what potential effect this approach has on maximising the utilisation of nonrenewable aggregate resources.

The importance of the quality of aggregate fines and some of the specific deleterious minerals of concern are discussed in the context of New Zealand mineralogy (although the findings are relevant to countries with similar weakly metamorphosed sedimentary rocks). The methodology of both test methods and some of the limitations and concerns are also discussed.

The paper outlines the experimental program and testing that took place over a period of three months. The results presented and discussed for 380 samples
from seven quarries aimed at trying to establish a correlation between the sand equivalent and the clay index. In agreement with previous research it was concluded that no correlation between the two test methods exists (R2 = 0.08).

Possible reasons for a lack of correlation are presented, along with the concepts of a new ‘normalised’ clay index and a ‘steady state’ sand equivalent. Early results from an initial testing program are presented which demonstrate that the adapted testing methodology gives a stronger correlation (R2 = 0.65) between the two test methods and has the potential to give a better indication of an aggregate’s suitability for use.

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Travel time reliability and the bimodal travel time distribution for an arterial road

Paper 4

Susilawati, Michael AP Taylor and Sekhar Somenahalli

Invited paper
This paper was originally peer reviewed and presented at the 24th ARRB Conference, held in Melbourne October 2010, where it won the first ARRB Academy Young Researcher Award. It is published here with minor revisions but without
further review at the invitation of the Editor in order to make it available to a wider audience.

In relation to the development of travel time reliability metrics, previous studies had suggested that the travel time variability distribution might follow either normal or lognormal forms. From substantial new data observation undertaken in
Adelaide, including assessment of two sets of longitudinal trip time data, these distributions appear inadequate. Generally this is because the upper tails of the observed distributions are more substantial than those of the normal or lognormal
distributions. Additionally, there is some evidence of bimodality in some of the actual travel time distributions. Consequently, a number of questions arise: When does bimodality occur? How does it affect the measurement of travel time bariability and reliability? Hence, this paper investigates the existence of bimodality in travel time distributions and tries to answer those questions.

From the data it was found that the bimodality occurred when travel time observations for a given link actually belong to two different populations.
This occurs on links with traffic signals, in circumstances in which the traveller experiences two distinct modes of traffic behaviour: (1) when there is no delay at the traffic signals, and (2) when the traveller encounters a long delay. Bimodality is known to occur in other fields, such as the life test process in reliability engineering. The paper uses current research to measure the probability of the
separate populations. Using the mixture normal distribution functions, we can then refine and extend the previous travel time reliability metrics.

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Tourism impacts in South-East Asia from aviation carbon pricing

Paper 5

Daniel Veryard

Invited paper

This paper details the construction of a simple model that estimates tourism income impacts for selected Asia-Pacific Economic Cooperation (APEC) member economies of future marketbased measures to reduce international aviation
emissions. The model was commissioned by the APEC Transport and Tourism Working Groups in order to inform sustainable policy approaches to international aviation emissions. 

At its heart, the model uses price elasticities which capture variations between demand responses for visitors from different regions. To make the model operational, we explore key intermediate relationships between emissions pricing and international tourism income. For example, an examination of the nature, magnitude and importance of international aviation movements shows a diversity of aviation flows and levels of dependence on tourism income across sample economies.  Furthermore, the relationship between unit passenger costs of aviation, fuel prices and distance flown is found to be complex, with fuel costs per passenger increasing more rapidly than operating costs as distance increases.

Model results suggest that – within sample economies – proposed pricing measures are likely to reduce international aviation demand reductions by a maximum of 5%, while national income is expected to decline by a maximum 0.5% as a result.

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Adapting to climate change - implications for transport infrastructure, transport sytems and travel behaviour

Paper 6

Michael AP Taylor and Michelle Philp

Invited paper
This is a slightly revised version of a paper that was originally peer reviewed and presented at the 33rd Australasian Transport Research Forum held in Canberra, October 2010. It is published here without further review at the invitation of the Editor in order to make it available to a wider audience, as a contribution to current important scientific and policy considerations. All papers that have been
presented at the Australian Transport Research Forum since 1975 are accessible at www.patrec.org/ atrf.

This paper reviews land based transport related issues from considerations of climate change adaptation in Australia. The two main issues for climate change adaptation are sea level rise and the increased frequency and intensity of extreme weather events. These issues are considered in the paper. It considers the risks to existing transport infrastructure and the resulting considerations
necessary in planning new infrastructure, transport systems operations under changing climatic conditions, and potential changes in travel behaviour. The use and capability of regional rural networks in emergency evacuation planning
emerges as one particular area for further research. 
More generally, recognition of the risks associated with climate change is required for better planning of new infrastructure and mitigating potential damage to existing infrastructure. Climate change poses a significant risk to infrastructure and its owners, managers and operators. There is a need to undertake research into the likely impacts of climate change on Australia’s transport infrastructure,
establish the categories of infrastructure most at risk and outline opportunities for adaptation responses, and examine the current governance structures.  Then the administrative, legal and other issues that may impact on climate change adaptation can be identified.

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