Institute of Transportation, MOTC

       This study explores the factors affecting the violation of automobiles’ and motorcycles’ right-turn on red (RTOR). Five cross intersections (six driving directions) and three T-intersections in Tainan city were selected. Data were collected by video recording the selected 17 variables, including intersection geometry, road conditions, and driver factors, as well as traffic volume. The main analysis methods used are multiple regression analysis, t-test and one-way AVOVA. The results show that there are 10 factors affecting motorcycles in RTOR, including intersection type, weekdays or holidays, lateral motorcycle volume, lateral automobile volume, number of motorcycles waiting to turn, number of motorcycles waiting at red lights, number of automobiles waiting by red lights, red light cycle ratio, type of changing lanes, distance from the stop line to intersection. On the other hand, there are 9 factors affecting automobiles in RTOR, including the intersection type, weekdays or holidays, lateral motorcycle volume, number of motorcycles waiting by the red light, number of automobiles waiting by the red light, the red light cycle ratio, type of changing lanes, motorcycle waiting zone, and motorcycle left turn waiting zone. The factors affecting RTOR of automobiles and motorcycles are different. First of all, motorcycles tend to RTOR at cross intersections, but automobiles tend to RTOR at T-junctions. Furthermore, the more automobiles and motorcycles stopped by the red light, the higher motorcycle RTOR rate, and the lower automobile RTOR rate. Finally, the longer the red light phase time, the higher motorcycle RTOR rate, and the lower automobile RTOR rate. The research results also pointed that under the condition of more driving road lanes, both motorcycle’s and automobile’s RTOR rate are higher, but the distribution of the RTOR rate is not obvious for the number of entering road lanes.