This study deals with a cost benefit analysis of the Balsi Beam Crash protection System. This system has been developed by the California Department of Transportation (Caltrans) to provide positive protection for the highway workers. California highway work zone injury data for a period of 10 years was evaluated to understand the relevant parameter sin highway work zone accidents. A statistical analysis of this data was performed and showed that five parameters (Work Activity Type, Time of Day, Work Zone Duration, Vehicle Miles of Travel of the area, and the Location or Type of Roadway) have the most significant effect on injury severity. An Injury Risk Index is then defined to capture the composite effects of all these five parameters in a single metric for use in risk assessment and cost benefit analysis. The study then develops a cost model and combines it with the Risk Index to evaluate the risk mitigation and averted injury cost benefits achieved by the use of the Balsi Beam Barrier system at appropriate work zones. The study also develops methods for evaluating additional operational costs of the Balsi Beam Barrier system but since these costs are found to be dependent on site specific information they only sample calculations are provided. Although the methods developed in this study provide a basis for cost benefit analysis and risk assessment of the Balsi Beam Barrier as well as other Barrier systems, the specific data on actual injury cost averted should be used very carefully due to the limited nature of the data set and the fact that some unfortunate fatalities existed in the data set increasing the overall averted cost of injuries.