การจัดการความเร็วในช่วงเปลี่ยนแปลงบนถนนชนบทก่อนเข้าเขตชุมชน

Abstract

Overspeed is one of the main factors contributing to several crashes that occurred on national highways and rural roads between the years 2013 and 2017. Also, most of those crashes occurred on the road sections that pass through the community or approach to the community. These problems should be solved urgently. The objectives of this research are to study and to propose a guideline for an installation of traffic calming devices in the transition zone on rural roads approaching a community area. In the research, a comparative analysis was used to measures the effectiveness of three traffic calming devices, including on the overhang sign, typical the Optical Speed Bar (OSB), and the OSB with red-colored surfacing. The rural road No. SK2031, section passing Wat Khow Kloy community, and the rural road No. SK3005, section passing Wat Hin Kliang community, were selected as two case studies. The results for the case of Wat Khow Kloy showed that the overhang sign reduced 85th percentile speed 2.5 kph (or 3.52%) when the typical OSB and the OSB with red-colored surfacing reduced 4.0 kph (or 3.50%) and 15.0 kph (or 14.82%), respectively. Regarding Wat Hin Kliang case study the results showed that the overhang sign reduced 85th percentile speed 8.2 kph (or 8.70%) when the typical OSB and the OSB with red-colored surfacing reduced 9.1 kph (or 9.60%) and 15.0 kph (or 13.00%), respectively. The results from the two case studies were subsequently applied to estimate the speed after installing the three types of traffic calming devices on the national highway No. 3048, section passing Tha Lan community. The results showed that the typical OSB was the most suitable in terms of the benefit-cost ratio which were between 4.82 (exclude the impact of access roads) and 8.86 (include the impact of access roads). However, in terms of the net benefit, the OSB with red-colored surfacing provided the maximum benefit. Therefore, the installation cost may affect the selection of traffic calming devices. But if there is no budget constraint, the device may be chosen based on the net benefit. The results of this study could be a guideline for relevant agencies in order to apply the traffic calming devices on rural roads approaching community areas.