Cost Saving and Carbon Reduction Strategies of Pavement Rehabilitation

• Main Authors: Ning Lee, 李寧
• Other Authors: Chia-Pei Chou
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/01739930589430028534

碩士 === 國立臺灣大學 === 土木工程學研究所 === 104 === The aim of the study is to find out feasible strategies for cost-saving and carbon reducing of pavement rehabilitation (milling and overlay) and estimate the potential of CO2 reduction of pavement rehabilitation strategies by lifecycle cost inventory and CO2 emission inventory. According to literature review, expert interview, and model derivation, it was found that the most important factors for cost saving and CO2 reduction are lower expense of natural material and longer service life of each milling and overlay. Alternatives evaluated in this study are designed based on change of material (by reclaimed asphalt mixture and stone matrix asphalt mixture, improve construction quality (providing lower initial roughness), and thicker dense grade layer of the pavement structure. The length of the analysis period in this study is 40 years of operation and maintenance of pavement that set based on the characteristic of the National Freeway in Taiwan. The software of AASHTO (American Association of State Highway and Transportation Officials) latest design guide, MEPDG (Mechanistic-Empirical Pavement Design Guide) is used to predict the length of service life that every milling and overlay provides of each alternative. All factors that used in the simulation, like amount of daily truck traffic, basic structure, and climate are set as close as possible to the real situation in Taiwan. The analysis shows that lower initial IRI (International Roughness Index) leads to the least CO2 emission and rehabilitation cost. Improving the construction quality provides the best performance for financial and environmental sustainability. Secondly, using reclaimed asphalt mixture also shows good performance in the two phases. Thicker dense grade layer does not benefit to neither economical nor environmental phases. Using SMA mixture as replacement of part of dense grade layer has benefits on cost saving, but does not make significant contribution to CO2 reduction. For the short term, improving construction quality is what Taiwanese highway agencies should do first to save maintenance cost and reduce CO2 emission. Although Taiwanese government does not levy a tax on CO2 emission so far, with the trend of CO2 reduction across the world, it is possible that all of the emission must pay for carbon rights. Since some of the alternatives evaluated in this study shows good performance on reducing CO2 emission, like lower initial IRI and use reclaimed asphalt mixture, those methods should be applied to exchange more carbon rights for road rehabilitation. Those alternatives also provide good potential on CO2 reduction. For example, it is suggest that the authority must reduce 7.92 million tons of CO2 every year to meet the national emission reduction targets. According to the inventory in this study, if the initial IRI of highway pavement has been lower to 100 in./mi. (1.57 m/km), the amount of CO2 emission would decease 10,831 tons, about 1.37% of the reduction target (7.92 million tons). Improving the construction quality is undoubtedly the most urgent task for Taiwanese road agencies.