Firstly applied by the U.S. Nuclear Regulatory Commission, risk analysis has quickly become an efficient methodology to apply in many industries, which have to deal with uncertainty. The nuclear industry, and more recently transportation (land and air), space, and food safety industries promote a greater use of risk analysis in their operations, and policy decision making. Aiming at modelling the cause-and-effect chain of driver behaviour, a new methodology of risk analysis, Darmstadt Risk Analysis Methodology (so-called DRAM), has been developed 15 years ago. This present study explains the application of DRAM in the situation of motorcycle-dominated traffic flow. In recent years, along with an amazing economical development, mobility demand in Vietnam has increased quickly, which can be clearly seen with the increased number of registered mobile vehicles. Due to its characteristics of movement and economics, motorcycles (two-wheeled vehicles) are still the most common transportation mode in the whole traffic system in Vietnam. They are also main causes to the unordered and unsafe situation of traffic system at present. The author presents findings from analysing the current situation of traffic safety. From statistical data, human behaviour is at the highest rank in the list of causes leading to traffic accidents. The study describes different approaches to conduct risk analysis in motorcycle-dominated flow based on analysing the accident progress (dealing with the gap between normal situations and critical situations). From the physoslophy of Conflict Technique in car traffic flow, it is provided with two concepts of “conflict zones” and “conflict time segments” which can be further developed to determine the hazard that drivers have to face with in their left-turning movement at intersections in motorcycle-dominated traffic flow. Both concepts are relevant in case of the distinguishing characteristics of non-lane based movement of motorcycles. After general analysis the situation, the study focuses on the main cause of the traffic unsafety in Vietnam nowadays: driver behaviours of violating road traffic regulations. Applying risk analysis methodology of DRAM, the study aims at answering three questions: (i) why do drivers violate the traffic regulations? (ii) how often do they violate the traffic regulations; and (iii) what are the consequences of such kind of behaviours. The chain of “Driver behaviours of violating traffic regulations” based on “General attitudes towards road traffic regulations” and “Specific-scenario acceptance of rules” is constructed. A case study of two policies in Vietnam is analysed as the illustration. The results are recommended to apply to evaluate and verify traffic safety measurements in the future.