Deceleration rate, time to collision and impact speed have been commonly employed as accident risk indicators. However, it is hard to assess the level of accident risk since these indicators have not been developed with measurable score criteria. This study focuses on the determination of measurable risk indicators which could be used to assess accident risk level and to determine more appropriate accident risk management strategies by using the descriptive qualitative approach. The data were collected from a braking maneuver test conducted on a dry and level closed circuit course. Risk was a function of accident probability and its possible consequences, while accident probability was determined based on the safety factor, i.e. the ratio of available stopping sight distance (ASSD) to minimum SSD (MSSD), which was used to determine the margin of safety. Subsequently, accident consequence was determined using the impact speed at a predicted point of collision along the braking distance path. The results show that accident risk could be easily determined using the proposed indicators, whilst an objective and appropriate accident risk management strategy could be determined based on the minimum margin of safety value which could be obtained from each risk exposure.
Trading, agriculture, transportation and communication as well as services sectors are the prime contributors of the regional gross of domestic product in the island of Timor. However, the increasing of such priority sectors was relatively constant which might be occurred due to inappropriate efforts in integrating the transportation infrastructure and potential social-economic activities intra and/or inner districts. This paper focusing on how to increase such regional social-economic structure by developing better transportation services system which is assumed could attract tourism traveling number, i.e. based on integration between railways transportation system and local natural resources and/or social-economic activities. The indication of technical, economic, social and environmental as well as institutional arrangement feasibility then was analyzed using SWOT model. It was strongly indicated that the development of transportation network services based on railways network could trigger the augmentation of not only tourism trips but also the type, number, scale and spatial distribution of social-economic activities along the Northern coast of the island of Timor, as well as the regional gross of domestic product of both countries
Thus far, minimum stopping sight distance (SSD) is determined based on design speed, a minimum reaction time of 1.64 s and a deceleration rate of 3.4 m/s², whereas in certain situations the latter can be shorter than 1 s and higher than 4.5 m/s². Awareness of this can trigger speculative behavior, as can be seen from the choice of speed and/or the critical crossing gap, which is often smaller than the recommended minimum SSD. This study focused on the development of an appropriate minimum SSD model that is suited to risky conditions at an unsignalized intersection and its possible usage in accident risk evaluation, particularly for motorcyclists. The data were taken from direct measurements and related studies. Variables that potentially influence minimum SSD were tested. The results strongly suggest that the speed reduction achieved by downshifting significantly influences both the braking distance and the impact speed. Moreover, the minimum SSD obtained from the proposed model significantly differs from that obtained from a similar model recommended by AASHTO. Therefore, it is worthwhile to consider the application of the proposed minimum SSD as an accident probability indicator parameter.
Although right turning movement frequency due to exiting-entering vehicles from or to the social-economic area, particularly located nearby an intersection, could influence travel delay and/or vehicle queuing but it has not been considered when determining both the roadway and intersection capacity and performance. Consequently, they may not describe the actual problems occurred there. Accordingly, this paper investigates it by describing risky situation occurred at two un-signalized intersections which consist of similar traffic and roadway situation. Effect of the right turning frequency to the degree of saturation, delay time and accident risk then was discussed. It was found that the level of side friction were in the low-level categories so that theoretically it does not affect the travel speed and/or degree of saturation. However, the obtained delay time was around 40 s so that it triggers riders to increase their approaching speed to avoid delay which in turn increases accident risk because at the same time the opposite riders insist on crossing the major stream with average critical gap acceptance of 20 m. This strongly indicates that the right turning movement should be considered when determining road performance, urban speed limit, and traffic impact analysis
Kupang City is an area in Indonesia which has a relatively low number of rainy days. This causes the supply of clean water or drinking water in Kupang City to decrease. The high infiltration rate not only increases the amount of water stored in the soil, but also reduces flooding and erosion caused by run off. This study aims to model the relationship between infiltration and discharge capability for each type of samples land by using linear regression method. For this reason, a water absorption test was conducted on the built up area based on the infiltration rate. The results of experiments and calculations using linear regression shown that area often received heavy load such as vehichles had lower infiltration rate leading to slow inundation height decrease. While areas rarely received heavy load had higher infiltration rate. Even though the difference is only around 2-3 cm / 5 minutes, it indicates that the availability of open areas is still needed to support the implementation of the zero run-off model in urban built areas
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