Traffic Conflict Types and Events on Selected change direction U-Turn Openings (Case Study)

Abstract

Traffic safety measures mainly depend on traffic conflict strategies, which are effective in supplementing crash prediction or crash potential estimation in different situations. In some cases, accident information are not available; thus, researches on traffic conflicts can indicate whether any situation is hazardous or not. Furthermore, unsafe vehicle manoeuvres at any highway facility can be evaluated by collecting data on traffic conflicts. Highway facilities geometric designs such as intersections or U-turn opening  can be effectively evaluated in terms of safety and performance quality from conflict studies.

Three U-turn mid-blocks at different locations in Najaf were selected for a case study, which is part of a comprehensive study on traffic characteristics and driver behaviour in the city. These locations included the U-turn at the Kufa–Najaf highway in front of University of Kufa, the first U-turn at the Ghadeer–Karrama highway from the Al-Iskan bridge and the U-turn at the Al-Iskan highway near the General Traffic Directorate. Six types of conflicts, which are standard with traffic volume changes and event repetition, were studied and analysed. The field survey included three normal workdays (minimum of 4 h every day between 7AM. And 3PM each hour divided on 3 sessions of 15 min separated by breaking period), depending on the amount of video data recorded for traffic conflict at each selected U-turn opening. The data collected were analysed in terms of repetition with traffic volume. Results showed that the secondary U-turn conflict (Con.4) and U-turn opposing direction conflict (Con.5) follow a similar change trend with a higher increase rate compared with that of other types. Moreover, the U-turn–pedestrian/bicycle conflict (Con.2) appeared to be the highest level in the first U-turn (U1) because of the higher demand for crossing road to reach University of Kufa. Last but not least, a huge gap was observed between traffic conflicts and events that eliminate the hazards of the U-turn section due to large traffic volume and driver awareness behaviour. Furthermore, traffic volumes appeared to be slightly affected in Con.2 that prove the hazards of the U-turn section due to large traffic volumes and uncontrolled driver behaviour. On the basis of the above findings, it's essential to recommend on the important of improvement of road infrastructure, enhancement effective regulations and enforcement, implementation of highways safety training to increase road user awareness and as a results increase traffic safety in the hole city.