This study investigated two methods that can be used to calculate the lateral deflection and the number of segments that move in a Plastic Water-Filled Barrier (referred to in the study as a “PWB”) after a vehicle has struck the traffic barrier. In the first method, theoretical equations were developed based on the conservation of energy. The second method used MADYMO (MAthematical DYnamic MOdels) simulations to calculate how the barrier deformed. The theoretical equations and the MADYMO simulation models developed in this study were validated against full-scale crash tests. A total of 23 full-scale crash tests were used to validate the theoretical equations. Comparison of the results indicate that both the theoretical method and MADYMO modeling simulation can be used to determine the PWB’s lateral deflection and the number of segments that move during impact with reasonable accuracy. The significance of this study is that cost-effective methods developed in this research can be used so that lateral deflections of almost all certified PWB systems under different impact conditions can be determined. Had full-scale crash tests been used to obtain the curve, the cost would have been considerable. The findings of this study would be useful for both Plastic Water-filled Barrier providers and users. PWB designers can now provide more information about their products, such as the possible working width and the number of segments that would most likely move for different impact severities. Highway engineers can also use the findings of this study to properly select and install a PWB system for different site and traffic conditions. 42″ Jersey Shape LCD, which is rated for high speed construction zones.