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Henning T.F.P.,University of Auckland | Roux D.C.,MWH New Zealand Ltd.
Journal of the South African Institution of Civil Engineering | Year: 2012

This paper details findings from the New Zealand Transport Agency's research project by Henning and Roux (2008). It forms part of the overall New Zealand Long-term Pavement Performance (LTPP) programme. The paper documents the development of prediction models for dense-graded asphalt (AC) surfaces and open-graded porous asphalt (OGPA) surfaces. Two models were developed including crack initiation on AC surfaces and ravelling initiation on OGPA surfaces. Continuous probabilistic models were utilised for both crack and ravelling initiation in order to predict the probability of the defect occurring. Models developed during this research use data which is readily available on network level databases, and can therefore be applied to asset management applications such as the New Zealand (NZ) dTIMS system (NZ's nationally adopted pavement management system (PMS)). Although a crack initiation model was also developed, it was not as robust as the ravelling model. Further work required includes refining of the models based on the LTPP data which includes bitumen property data. Although the developments are solely based on NZ data, there are a number of aspects applicable to the South African context. Firstly it presents a novel way of modelling the performance of asphaltic surfaces. Secondly it demonstrates some practical implications of maintenance practices that are sometimes considered for South African conditions. Source


Lai F.,University of Leeds | Carsten O.,University of Leeds | Tate F.,MWH New Zealand Ltd.
Accident Analysis and Prevention | Year: 2012

The UK Intelligent Speed Adaptation (ISA) project produced a rich database with high-resolution data on driver behaviour covering a comprehensive range of road environment. The field trials provided vital information on driver behaviour in the presence of ISA. The purpose of this paper is to exploit the information gathered in the field trials to predict the impacts of various forms of ISA and to assess whether ISA is viable in terms of benefit-to-cost ratio. ISA is predicted to save up to 33% of accidents on urban roads, and to reduce CO 2 emissions by up to 5.8% on 70 mph roads. In order to investigate the long-term impacts of ISA, two hypothetical deployment scenarios were envisaged covering a 60-year appraisal period. The results indicate that ISA could deliver a very healthy benefit-to-cost ratio, ranging from 3.4 to 7.4, depending on the deployment scenarios. Under both deployment scenarios, ISA has recovered its implementation costs in less than 15 years. It can be concluded that implementation of ISA is clearly justified from a social cost and benefit perspective. Of the two deployment scenarios, the Market Driven one is substantially outperformed by the Authority Driven one. The benefits of ISA on fuel saving and emission reduction are real but not substantial, in comparison with the benefits on accident reduction; up to 98% of benefits are attributable to accident savings. Indeed, ISA is predicted to lead to a savings of 30% in fatal crashes and 25% in serious crashes over the 60-year period modelled. © 2011 Elsevier Ltd. Source


Parthan S.R.,University of Canterbury | Milke M.W.,University of Canterbury | Wilson D.C.,Imperial College London | Cocks J.H.,MWH New Zealand Ltd.
Waste Management | Year: 2012

The importance of cost planning for solid waste management (SWM) in industrialising regions (IR) is not well recognised. The approaches used to estimate costs of SWM can broadly be classified into three categories - the unit cost method, benchmarking techniques and developing cost models using sub-approaches such as cost and production function analysis. These methods have been developed into computer programmes with varying functionality and utility. IR mostly use the unit cost and benchmarking approach to estimate their SWM costs. The models for cost estimation, on the other hand, are used at times in industrialised countries, but not in IR. Taken together, these approaches could be viewed as precedents that can be modified appropriately to suit waste management systems in IR. The main challenges (or problems) one might face while attempting to do so are a lack of cost data, and a lack of quality for what data do exist. There are practical benefits to planners in IR where solid waste problems are critical and budgets are limited. © 2011 Elsevier Ltd. Source


Parthan S.R.,University of Canterbury | Milke M.W.,University of Canterbury | Wilson D.C.,Imperial College London | Cocks J.H.,MWH New Zealand Ltd.
Waste Management and Research | Year: 2012

The need for improved cost planning methods for solid waste management (SWM) is particularly strong in emerging economies where problems are severe, expectations for improvements are high, but finances are constrained. Estimating cost functions is suggested as an improved cost planning method. The research uses 1999 data from 298 Indian municipalities, covering over 140 million people. Stepwise multiple regression involving eight predictor variables was conducted on costs to detect any statistically significant correlations. The average costs on either a per tonne or per capita basis are most influenced by the total number of staff employed per capita or per tonne. The results are believed to be due to labour costs being such a high fraction of total costs in developing countries. Due to high variability in labour intensity between municipalities the data showed no clear correlation between per tonne or per capita costs and population, indicating no economy-of-scale. The data used here are subject to significant conjecture over their quality and age; however, the unique nature of the study should help future researchers investigating costs in emerging economies. © 2012 The Author(s). Source

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