Transportation is one of the most important infrastructures that sustain social and economic activities in urban environments. Motorization, which originated in the United States in the 1920s, has widely progressed all over the world. Modern life requires motorized transportation facilities, and developed countries such as the United States and the UK have developed roadway plans to manage increasing traffic demands. Advanced traffic management systems based on intelligent transportation systems (ITS) have also been introduced to improve traffic efficiency and safety. As a result, although many problems still exist in urban transportation systems, traffic efficiency and safety have significantly improved since the dawn of motorization. Thus, it is

5.1 Introduction 101 5.2 The On-Road Traffic Situation in Asian Countries 102 5.3 Characteristics of Mixed-Traffic Flow 105 5.4 Design of Signalized Intersections for Mixed Traffic 107

5.4.1 Basic Concept of Traffic Capacity at Signalized Intersections 107

5.4.2 Criticisms of PCU Value 108 5.4.3 Capacity Analysis Considering Approach Designs 110 Intersection Designs 110 Estimation Method of Traffic Capacity 112 Optimal Approach Design 115

5.5 Road Safety Issues in Mixed Traffic 117 5.6 Conclusion and Recommendation 120 References 120

natural that such traffic management systems have been introduced in Asian countries with less developed motorization. However, Southeast Asian motorization differs significantly from Western motorization. In most Southeast Asian countries, motorcycles play a more important role in urban traffic than four-wheel passenger vehicles. This gap between the target of the introduced traffic systems and actual traffic conditions leads to severe traffic congestion in urban environments, affecting road safety as well. Therefore, it is necessary to develop traffic control systems suitable for the local traffic situations specific to Asian countries to ensure human security and sustainable development in urban areas.