Highlights • Wrong lane riding is one of the most prevalent risky behaviours among adolescents operating (electric/motorised/non-motorised) two-wheelers in Vietnam. • Expectancy Value Theory is used to model the different belief components behind the key-determinants of behavioral intention as proposed by the Theory of Planned Behaviour. • In addition to the simple belief components (e.g., outcome beliefs and outcome evaluations), behavioral, normative, and control belief product terms statistically significantly increased the variance explained in the intention to engage in wrong lane riding. • More detailed insight into the specific beliefs that drive wrong lane riding can help practitioners and policy makers come up with more effective interventions. • Interventions aimed at reducing wrong lane riding should best target both the cognitive and affective components of attitude, subjective norm, and perceived behavioural control.

Abstract Introduction: In Vietnam, road traffic crashes are one of the leading causes of death and serious injury in adolescents, especially in the 15–19-year age group. Wrong lane riding (WLR) is seen as the most common risky behavior of adolescent two-wheeled riders. This study (a) tested the expectancy-value model held to underpin the key determinants of behavioral intention (i.e., attitude, subjective norm, perceived behavioral control) as proposed by the Theory of Planned Behavior, and (b) identified appropriate targets for road safety interventions. Method: A cluster random sample of 200 adolescent two-wheeled riders in Ho Chi Minh City participated in a cross-sectional study designed to measure the variables of interest (i.e., behavioral beliefs, normative beliefs, control beliefs, and intention towards wrong lane riding). Results: The results of hierarchical multiple regression lend clear support for the expectancy-value theory as an approach to model the different belief components behind the key determinants of behavioral intention. Conclusion: Road safety interventions aimed at reducing WLR among Vietnamese adolescent two-wheeled riders would best target both the cognitive and the affective components of attitude, subjective norm, and perceived behavioral control. Interestingly, the sample investigated in this study is rather negatively predisposed toward WLR. Practical Applications: It is recommended to further strengthen and stabilize these safety-oriented beliefs, and to develop the required implementation intentions to guarantee that the appropriate goal intentions in terms of WLR are translated into action. More research is needed to see whether the commission of WLR can also be explained in function of a reactive pathway, or is exclusively under volitional control.