A methodology for evaluating the effectiveness of freeway incident management (FIM) systems is presented. Evaluation of the effectiveness of a FIM system requires the establishment and estimation of the measures of effectiveness. For the estimation of the measures of effectiveness of a freeway incident response system, a simulation model that focuses on the operations of freeway emergency response units (FERUs) has been developed. Various aspects of the system are covered. First, an analysis of the arrival rates of mobile servers to the incidents to be serviced is done. These incidents occur randomly, follow discrete temporal and spatial distributions, and are of different natures and severities. Then, on the basis of the number of the mobile servers, the area in which these servers provide service to emergency calls is divided into smaller districts and the mobile servers are assigned to each one of the districts. The proposed simulation model generates freeway incidents according to their spatial, temporal, and severity characteristics. Alternative dispatching policies have been integrated in the model for the assignment of FERUs to incidents. The proposed model has the ability to estimate the total time that has elapsed between the occurrence of the incident and the completion of the service and to provide alternative emergency response policies. The value of alternative measures of effectiveness is calculated as a function of the total service time, and the performance of these policies is evaluated.