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Sawangsuriya A.,Bureau of Road Research and Development | Ketkaew C.,Tak Office of Highways | Sramoon W.,Mahanakorn University of Technology
Geotechnical Special Publication | Year: 2012

A compaction quality control (QC) in highway construction in Thailand is typically based on an in-place density measurement using the sand replacement method. Although monitoring compaction quality through a sand cone density test is relatively simple, such method is generally time consuming, labor intensive, less cost-effective, and destructive. This paper presents the laboratory evaluation of an innovative QC tool called the soil density gauge (SDG), which provides rapid and instantaneous measurement of density and moisture content based on the electrical impedance spectroscopy. The SDG was evaluated in a test box. Six highway materials were used in the study. The variation of SDG measurements along with its measurement characteristics was investigated herein. The paper also compared the SDG density and moisture content measurements with other tests such as the nuclear gauge, the soil stiffness gauge, and the sand cone method etc. © 2012 American Society of Civil Engineers. Source

Lertworawanich P.,Bureau of Road Research and Development | Karoonsoontawong A.,King Mongkuts University of Technology Thonburi
Transportation Research Record | Year: 2012

Pavement markings are one of the most important highway assets. Good pavement markings provide good visibility for traffic, whereas poor pavement markings can adversely affect traffic operations on highways. However, a limited amount of research has been conducted on the effects of working conditions on the service life of pavement markings. This paper presents duration models for retroreflectivity of thermoplastic pavement markings in Thailand. This approach allows the service life of pavement markings to follow probability distributions in which model parameters are assumed as a function of relevant independent variables such as traffic volumes. The maximum likelihood estimation technique was used to estimate means and standard errors of the model parameters. Retroreflectivity data of thermoplastic pavement markings were collected from the eastern highway network of Thailand, which consists of more than 5,000 km of highways in various traffic conditions. The analysis results showed that traffic volumes had negative effects on the service life of the pavement markings. This paper proposes a preemptive goal program for approximating required budgets to ensure the maintenance of the percentages of good condition pavement markings over the planning horizon. The first-priority goal is to maintain the percentage of control sections that are in good condition, and the second-priority goal is to minimize total maintenance costs. In the illustrative example, the inconsistency between the Thailand Department of Highways' specifications and field practices caused estimated required annual budgets and the deterioration of pavement markings to greatly fluctuate over the planning period. For more consistency between specification and field practice, the proposed models will be applied in a pavement marking management system. Source

Fowze J.S.M.,Asian Institute of Technology | Bergado D.T.,Asian Institute of Technology | Soralump S.,Kasetsart University | Voottipreux P.,King Mongkuts University of Technology Bangkok | Dechasakulsom M.,Bureau of Road Research and Development
Geotextiles and Geomembranes | Year: 2012

Recently, the frequency of rain-triggered landslides in Thailand has been on the increase and has gained momentum, coincident with the effects of climate change. In this regards, the impact of landslide on roads and highways in the hilly and mountainous terrains has also increased. Non-structural landslide mitigation measures, including early warning and hazard mapping, as well as structural mitigation measures with the application of geosynthetics, have been exploited in localities where rain-triggered landslides are a potential threat to human life and property. For early warning, the use of critical Antecedent Precipitation Index (API) is proposed to be most appropriate. Furthermore, deterministic hazard mapping technique incorporating the modern day geospatial technologies can also provide a useful platform to analyze a number of scenarios including rainfall and land cover/land use variations. Finally, a parametric study on a designed and constructed reinforced soil slope with polyester polymer geogrids revealed that the stiffness of backfill is very sensitive to moisture contents or wetting due to rainfall which can influence the performance of reinforced slope structure. © 2011 Elsevier Ltd. Source

Ponlathep L.,Bureau of Road Research and Development
IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC | Year: 2010

Traffic signals are the main devices for controlling traffic to guarantee the safe crossing of opposing streams of vehicles and pedestrians. In this study, a simple cycle and split optimization method is developed for isolated intersections. The split optimization is based on the notion of minimizing delay per cycle while cycle length is adjusted according to the residual queues at the end of the cycle. Traffic dynamics at signalized intersections are represented on time-space diagrams using the shockwave theory and information from detectors installed upstream of intersections. Splits are incrementally adjusted so that the delay per cycle is gradually diminished. Cycles are modified to have an efficient use of the provided green times without causing the residual queues. Unlike most algorithms, the proposed method can manage traffic even when queues extend beyond detector locations. Simulation experiments on a two-one-way intersection with different demand scenarios are performed to demonstrate efficiency of the developed algorithm. Hypothesis tests are conducted to statistically verify the efficient comparison between the proposed method and the Webster formula. It is found that in case of fixed demand the proposed method can optimize splits and cycle lengths with no worse performance measures than the optimal fixed-time signal settings according to the Webster formula. For the variable demand case, the result indicates that the algorithm can adjust splits and cycle lengths in response to the change of demand and provides better performance measures than the Webster formula. ©2010 IEEE. Source

Jotisankasa A.,Kasetsart University | Mahannopkul K.,Kasetsart University | Sawangsuriya A.,Bureau of Road Research and Development
Geotechnical Engineering | Year: 2015

Spatial and temporal variations of pore water pressure within slopes in response to rainfall that lead to slope failure, are one of the major uncertainties in evaluating slope stability. This paper reports on the study of slope stability with respect to pore water pressure variation with rainfall during actual failure in September 2011. The studied slope, situated near the peak of Doi-Inthanon national park, Northern Thailand, consisted of granitic residual soil fill that suffered from soil erosion and shallow failure. The KU-tensiometers were installed to monitor both pore water pressure and suction in the slope. Various laboratory and field tests were conducted, namely, direct shear tests on both fully saturated and unsaturated soils, soil water characteristic curve, and field infiltration tests. Two-dimensional (2-D) Back analysis of slope stability, for failure event in 2011 suggested that the critical pore water pressure distribution can be assigned to the ru value of about 0.43 or u=0.43γH. Based on three dimensional (3-D) stability analysis, the pore water pressure can be 30% higher when compared with the 2-D analysis. 2-D Finite Element seepage analysis appeared to capture general trend of pore-water pressure change reasonably well. However, it seemed to underpredict the pore-water pressure at failure especially for depth greater than 2 meters. Source

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