การวิเคราะห์ทางแยกสัญญาณไฟจราจรที่มีเส้นหยุดรถ ข้างหน้าสาหรับรถจักรยานยนต์ในเขตเมืองเชียงใหม่

Abstract

"Motorcycle Box Intersection" is a signalized intersection that installed the advanced stop lines (ASL) for stopped motorcycles. Motorcycle boxes consist of a set of two stop lines. The first line is the stop line for motorcycles, and the following line is the stop line for other vehicles. Furthermore, the area between these two stop lines is the motorcycles waiting area for green signal. The ASL for motorcycles is beneficial by reducing the traffic conflicts of motorcycles with other vehicles. The ASL also increases the traffic performance of the signalized intersection and the safety of motorcyclists. However, there is no standard for installing the ASL for motorcycles in Thailand and no warrant for determining the proper use in each area. This research aims to (1) analyze the opinions of traffic engineering professionals and road users on the ASL for motorcycles, (2) apply the microscopic traffic simulation for analyzing the traffic performance of ASL for motorcycles at the signalized intersections in Chiang Mai city; and (3) propose the warrant of ASL for motorcycles in terms of design, planning installation, and performance evaluation. The results found that the design size of ASL should be 3 to 5 meters, which is placed next to the crosswalk for pedestrians. The traffic sign and road marking must be placed for restricting the other vehicles from violated in the motorcycles waiting area. The ASL's road markings can be used by two types – the symbol of MC and the characters of MC. Further, it can apply the green pavementon the motorcycle waiting area. For planning purpose, ASL must be installed at the signalized intersection. The recommended size of a traffic lane for ASL installation is 3 meters or more so that motorcyclists can filter through in front of the intersection. For safety purpose, the motorcycles volume must be greater than 100 vehicles per hour per lane in order to install the ASL. For operational performance, the motorcycle compositions should be greater than 20.0%, 16.7%, and 37.5% for intersections with 2, 4, and 6 lanes on the major road, respectively. The results of the traffic flow analysis from 25 simulations found that ASL for motorcycles reduces the average motorcycle departure time. However, it increases the average passenger car departure time. As an example of the simulation where the volume of motorcycles and passenger cars is 500 vehicles/hour/lane each, the simulation results of the intersections with 2, 4, and 6 lanes on the major road showed that the average motorcycle departure time has decreased by 10.6, 11.8, and 3.4 seconds, respectively. In contrast, the average passenger car departure time has increased by 2.7, 1.7, and 3.9 seconds, respectively. The results of the headway analysis found that ASL reduces the headway of motorcycles and passenger cars. Based on the simulation results where the volume of motorcycles and passenger cars is 500 vehicles/hour/lane each, the headway intervals between motorcycles reduce from 1.7 seconds to 1.0 seconds, and the headway intervals between passenger cars remain the same (from 2.5 seconds to 2.4 seconds). The statistical t-test found that the headway of passenger cars has no statistically significant difference after installing ASL. The results on the safety of the use of ASL for motorcycle found that ASL can help reduce the number of traffic conflicts caused by traffic in the same direction between the motorcycles and passenger cars, which is suitable for the split-phase signal. Furthermore, the ASL can increase the safety of motorcyclists by segregating traffic flow between motorcycles and passenger cars at the time of departing from all types of intersection and traffic signal phasing.