Widely-used existing penetration and viscosity grading systems have been found to be insufficient in characterizing performance of asphalt binders according to many researchers. It has been discovered that asphalt binders can have different temperature susceptibility and performance characteristics even if classified in the same grade using these two grading systems. Recognizing the limitation of these systems, the Strategic Highway Research Program (SHRP) was initiated in 1987 to develop performance based tests and specifications for asphalt binders and asphalt mixture design - the so-called SUPERPAVE. SUPERPAVE tests have been introduced to measure physical properties of asphalt binders that could be directly related to field performance such as resistibility to rutting, fatigue cracking and thermal cracking. This concept has been successfully implemented in the US and European countries. In Thailand, only penetration system has apparently been used by related authorities. Nowadays, there is an initiative to improve the current grading system in Thailand by replacing it with a PG grading system. Unfortunately, complex and expensive equipment are required for the SUPERPAVE grading system, which is still unavailable in Thailand. Moreover, knowledge is likewise limited in understanding system implementation. In addition, the SUPERPAVE specification is based on pavement conditions in the USA. Therefore, this study aims to develop a performance grading system using indirectly estimated parameters related to pavement performance and conditions in Thailand. After a validation of such developed system, it was found that the proposed performance grading system can be satisfactorily used to classify the performance of binders which is also comparable with the SUPERPAVE system. It should be, however, noted that the proposed system can be used as a transition until sufficient equipment are obtained and sufficient understanding on SUPERPAVE implementation are acquired.
The interfacial pressure between tire and pavement is known to exhibit a highly non-uniform distribution over its contact area. This differs significantly from the uniform contact pressure distribution used traditionally in pavement design and analysis. Past research efforts have recognized that the contact stress distributions are dependent on tire type, tire inflation pressure, wheel load, tire tread patterns and vehicle rolling characteristics. This paper discusses the development of a numerical model that is capable of describing the contact stress distributions at the interface between a rolling tire and the pavement. The theoretical development of the finite element-based simulation model is first described. This model is then validated against the experiment data available in the literature and is applied to simulate the stress distributions at the tire-pavement contact area under different rolling conditions.
Tunnels with 1.0km length or over are proven to be eco-friendly. However, driving in long tunnels is not conducive to traffic safety. Even though some studies have emphasized the traffic safety weaknesses of long tunnel driving, detailed studies are insufficient. This study analyzes the effectiveness of landscape images in a 11.055km long tunnel to improve driving safety through examining drivers responses and brain waves are against two scenarios: 1) with landscape images and 2) without landscape images, using a driving simulator based virtual reality driving experiment. Results show that the deviation of driving speed and shift distance from the centerline of driving lane are affected, and brain waves related to drowsiness reduce when landscape images are installed.
This study attempts to evaluate the heterogeneous influence of driving propensity on driving intention on expressways under the provision of ITS-based and/or traditional traffic warning measures. An Internet-based questionnaire survey was conducted to collect relevant data including drivers' actual driving propensity and their stated driving behavior (i.e., driving intention) under different combinations of information provisions and existing safety facilities. Heterogeneity in the driving intention is taken into account by developing a latent class ordered-response probit model. As a result, it is confirmed that the warning information with voice and image through ITS technology (car-navigation) is a more effective measure than existing safety facilities to improve their awareness for safe driving; it is statistically confirmed that the developed model shows different driving intention by heterogeneities of drivers' driving propensities when same traffic warning information is provided on expressway.
Traffic flow at urban intersections in Thailand is far from optimal as manifested by long queues, drivers' subsequent frustration which in turn has led to road accidents caused by drivers' disobedience of traffic signals. This paper describes the development of a new ITS technology to improve traffic flow at intersections and hence remedy the traffic accident situation. An Adaptive Traffic Signalization System uses CCTV cameras and image sensing software to detect vehicles on each approach of an intersection. The computation of parameters involves simulation of adaptive signal timing and phasing in order to arrive at the optimal phasing and cycle times. Software has been developed to count the number of lane changing vehicles which are the major cause of accidents at both intersections.
When discussing a roadmap for realizing trade liberalization and transport efficiency, a comprehension of the "quantitative effects" of the related policies could be highly supportive and suggestive. The authors developed a successive prediction system on trade value and international cargo flow that provides an effective tool for quantifying the impacts of trade and transport policy on international cargo shipping. In this paper, a forecasting system called "Trade and Logistics Forecasting System for the APEC region" is developed in such a way as to support the discussion for the realization of trade liberalization and transport efficiency among the APEC economies.
This paper investigates different types of bus drivers' salary structures built in the design of contracts between bus operators and bus drivers in urban bus transport markets of developing countries. This is to address their impacts on divergent drivers' behavior that consequently determine bus safety and service level of bus operation. The paper identifies how divergent drivers' behavior evolves from different types of salary systems under urban bus environment and their possible impacts on service level of bus operation. It also discusses the possible advantages and disadvantages of each salary system from the perspective of bus operators, passengers and social issues are discussed. Finally, this paper gives basic recommendations to improve the driver efficiency for better safety and quality of services, in particular for Yangon City, the former capital of Myanmar.
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