Browsing by Author "Henning, Theunis F. P."

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    Development of a Performance Prediction Model to Manage Flushing of Sprayed Seal Pavements
    Kodipply, Sachi; Ingham, Jason M.; Henning, Theunis F. P. (2015-06-04)
    Flushing is a defect which has a damaging effect on the functional performance of sprayed seal (chip seal) pavements. Accurate understanding of flushing can have a significant impact when predicting the future performance and maintenance needs of pavements. The reported study was conducted to develop a prediction model to effectively identify, asses and manage flushed pavements. The study also aimed to develop a decision-making tool for treating flushed pavements. This study utilized pavement data from New Zealand's Long-Term Pavement Performance programme and data analysis was conducted to develop a model to predict the flushing potential of chip seal pavements. Additionally, the study conducted laboratory testing on pavement samples from flushed chip seal pavements. The conducted tests included wheel tracking and rutting measurements, air void volume measurements, as well as computed tomography scanning and image analysis. The laboratory test results were used to supplement the outputs of the performance prediction model in detecting the mechanisms that were causing flushing. The outcomes of this study included a model that was able to predict a) the probability of flushing initiation, and b) the quantity of flushing on a pavement. This model was statistically robust where the flushing initiation model had an accuracy of 76%. The flushing prediction model and the laboratory results were incorporated into an overall pavement assessment guideline for flushed pavements. This assessment guideline will aid pavement practitioners with accurate identification of flushing on a pavement network as well as with selecting the best method of maintenance treatment for flushed chip seal pavements.
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    Life cycle cost analysis to identify the need for drainage renewal in maintenance of road asset: Case Studies from a New Zealand road network
    Mia, Mohammad N. U.; Henning, Theunis F. P.; Costello, Seosamh B.; McKegg, Campbell (2015-06-04)
    This paper presents life cycle cost analysis case studies of drainage improvements in pavement renewal sections. The methodology used was developed by the New Zealand Transport Agency (NZTA) and utilizes Net Present Value (NPV) and Economic Indicator (EI) as the tools for economic justification. Case studies on a number of renewal sites were conducted from a road network managed under a Performance Specified Maintenance Contract (PSMC) in New Zealand (NZ). Due to the contractual nature of a PSMC, that is a lump sum to manage the network for 10 years, the contractors are at risk of expensive maintenance and renewal costs from premature failure. Consequently, they have to be proactive in balancing investment for asset renewal, preventive and reactive maintenance on the road network. The majority of the network comprises of chipseal roads without any comprehensive drainage measures being present. The renewal sites selected for the case study range from flat rolling ground to rugged hilly terrain. There are side hills, natural streams, and bush areas beside the sites, thus making them particularly vulnerable to moisture induced failure. The outcome of the study is encouraging and indicates a positive gain in economic efficiency from the investment in drainage improvement. This study is the first step towards managing drainage on a road network in a more holistic manner, by identifying the costs and benefits of undertaking the appropriate investment.
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    Maximise levels of service using cross-asset portfolio renewals management
    Mason, Michael; Rangamuwa, Siri; Henning, Theunis F. P. (2015-06-04)
    Auckland Transport is tasked with managing its road and public transport assets in the most cost-efficient manner to deliver levels of service and manage risk across the asset portfolio. The renewals approach outlined in this paper is part of an optimized decision-making methodology that is helping improve customer satisfaction through a more robust, consistent and equitable approach to the management of transport assets and their levels of service across the region. Auckland Transport asset management has been developing a renewals optimization model (ROM) to help optimize the condition profile of the portfolio and provide investment options to balance levels of service, cost and risk for each asset class. It identifies the investment required to change the current condition profile of each asset class to a more cost-efficient state while having regard for funding constraints, levels of service, risk and whole of life cost. It uses accepted depreciation curves for each asset group, an interactive process of allocating investment for renewals by insuring the investment for each asset class achieves the desired level of service in a balanced manner. The tool also enables the development of portfolio investment options for renewals scenario decision making based on the specific requirements of each asset class. It achieves this by identifying the consequences of trade-offs between: - steady condition state to be achieved. - level of service required. - number of years allowed to achieve desired levels of service. - level of backlog that can be accepted based on risk, criticality, movement and public perception considerations. The outcome of this approach is a balanced long-term renewals programme that will help resolve inherited variations in the condition state of transport assets and their levels of service across the region.