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The purpose of this study is to evaluate optimal layout design of U-turns on basis of road safety for highways of Thailand. In Thailand, U-turns are one of major segments of highways after intersections, contributing to rural highway crashes. Different layout designs of U-turn and variation in its elements are influencing factors for drivers’ expec...
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This objective study was carried out to discover and model the causal relationships between globalization and stress. The study used a simple random sampling of 600 Thai farm workers. The variables measured were general demographic variables, globalization (i.e. transnational corporations, transnational practices and transnational economics), land...
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... The other types including the Uturn at intersection, roundabout [3,4]. The U-turn movement is more dangerous and having high accident since this movement is not control by traffic signals and it is dependent on the gap acceptance from drivers [5,6] . If the gap is not enough to make the Uturn and turning to the opposite side, the accident accrues due to the conflict with the opposite traffic [4]. ...
... 5). ...
Traffic simulation models play a major role in allowing traffic engineers to assess complex traffic situations such as U-turn section. Such models help in proposing solutions and proposing alternative scenarios without committing too many expensive resources and this models are necessary to implement alternative strategies in the field. Simulation traffic models can significantly improve the quality of road network planning and design in urban areas. According to filed observation, the U-turn movement cause traffic congestion at both origin and distention (opposite) roads. This study introduces many alternatives to enhance the movement at U-turn section. These alternatives have been tested by using simulation models. The PTV VISSIM software is used to development the models. This development model has been calibrated and validated by using filed data collected from Al-Diwaniyah city, Iraq. References [1] Combinido, J.S.L. and Lim, M.T., "Modeling U-turn traffic flow", Physica A: Statistical Mechanics and its Applications, Vol. 389, No. 17, (2010), 3640-3647. [2] Della, R. H., Hanafiah, Arliansyah, J., & Artiansyah, R. (2015). Traffic Performance Analysis of U-turn and Fly Over U-turn Scenario; A Case Study at Soekarno Hatta Road, Palembang, Indonesia. Procedia Engineering, 125, 461–466. doi: 10.1016/j.proeng.2015.11.123 [3] Al-Obaedi, J., "Investigation the effect of speed humps on merging time of u-turn traffic", Ain Shams Engineering Journal, Vol. 10, No. 1, (2019), 1-4. [4] Al-Obaedi, J., " Simulating the Effect of Speed Humps on the U-Turn Traffic", international Journal of Engineering, Vol. 32, (2019), Pages 1773-1780. [5] Meel I, Satirasetthavee D, Kanitpong K, Brannolte U. The Optimal Design of UTurns on Thai Highways. Acta Technica Jaurinensis 2014;7(1):21–32. [6] Meel I, Brannolte U, Satirasetthavee D, Kanitpong K. Safety impact of application of auxiliary lanes at downstream locations of Thai U-turns. IATSS Research 2017;41(1):1–11. [7] Meel, I., "The optimal design of u-turns on thai highways", Acta Technica Jaurinensis, Vol. 7, No. 1, (2014), 21-32. [8] Yang, X. (2001),” CORSIM-Based Simulation Approach to Evaluation of Direct Left Turn Versus Right Turn Plus U Turn from Driveways. (Ph.D dissertation), University of South Florida, Tampa. [9] Detemple, J., Garcia, R., & Rindisbacher, M. (2007). Chapter 21 Simulation Methods for Optimal Portfolios. Handbooks in Operations Research and Management Science, 867–923. doi:10.1016/s0927-0507(07)15021-0. [10] Vaitkus, Audrius, et al. "Traffic Calming Measures: An Evaluation of the Effect on Driving Speed." PROMET –Traffic &Transportation 29.3 (2017): 275-285.doi: 10.7307/ptt. v29i3.2265. [11] World Health Organization. Global status report on road safety 2015. World Health Organization, 2015 [12] AL-Jameel H. A. E (2014). Contribution to the U-turn design at median opening in Iraq: Al-Najaf city as a case study, Kufa Journal of Engineering (K.J.E). [13] Della, R. H., Hanafiah, Arliansyah, J., & Artiansyah, R. (2015). Traffic Performance Analysis of u-turn and Fly Over u-turn Scenario; A Case Study at Soekarno Hatta Road, Palembang, Indonesia. Procedia Engineering, 125, 461–466. doi: 10.1016/j.proeng.2015.11.123 [14] Zainab A T Al-Kareawi and Jalal T S Al-Obaedi (2021). Simulation of U-turn traffic based on VISSIM and PARAMICS micro simulation, J. Phys.: Conf. Ser. 1895 012030 doi:10.1088/1742-6596/1895/1/012030.
... Some U-turn sites has an auxiliary lane prior to the U-turn sites to provide storage area and to minimize the effect of the turning traffic on the through traffic. Another benefit regarding the use of such auxiliary lane is to reduce accident rates at U-turn's locations [1,2]. ...
Median U-turn has been widely used at Iraqi highways and regards as one of sources of traffic congestion creation due to the fact the U-turn movements conflict with traffic at the origin and destination directions. To enhance traffic safety at U-turn sites, speed humps were installed to force speed reduction to the incoming traffic that conflicting with the turning traffic. This paper used real data taken from four median U-turn sites. Three of these sites has speed humps while the fourth is not. VISSIM traffic simulator has been used to build simulations models that could replicate the real site movements. The observations of traffic data for these sites have been conducted using video recordings to obtain traffic parameters contains traffic volumes and the time spent for tuning process. The simulation results based on traffic volumes and average time spent (ATS) for turning has been compared with the real data based on calibration and validation processes and good agreements have been obtained. The developed simulation models were used to examine different scenarios affecting the capacity of the U-turn traffic. The results suggested that the capacity is increased with the decreasing of speeds of opposing traffic and also with decreasing the distance between a speeds hump and the U-turn location.
... One of the common types of U-turn section is the "median Uturn" that provides special path (opening) through medians of multilane highways to allow traffic from making their turn into the opposite direction. Another type of U-turn section is represented by allowing traffic from making U-turn movement at intersection and roundabouts [9][10][11]. ...
... The geometric layout of the U-turn section may has an acceleration lane that allows storing U-turn traffic that waiting for appropriate gap in the opposite directions. Another benefit regarding the use of acceleration lane is to reduce accident rates at U-turn's locations [10]. ...
... According to Meel et. al, [2,3], the U-turns represents one of the most highway parts that causing in having high rates of traffic accidents. The design of U-turn with an axillary lane was found to effective way to enhance safety at U-turn's locations. ...
The median U-turn involving allowing traffic to move toward opposing direction through providing special
paths on a highway’ median. Such left turn movements causing delays for both merging and the
opposing main stream traffic. In order to ease the turning process, speed humps are widely used to by
impeding the upstream opposing traffic. This paper evaluates the effectiveness of using such humps through using real traffic data taken from three sites at Al-Diwaniya city, Iraq. The selected sites representing the cases of with and without speed humps. Video recordings is used to collect traffic data and the average time spent (ATS) while turning (merging) is used as a factor to show the effectiveness of using speed humps. The results show that the speed humps cause in significant reduction in ATS for turning traffic. Regression models have been developed to estimate merging time spent based on opposing flow rates.
