ABSTRACT: The Florida Department of Transportation (FDOT) is interested in updating its methodologies for estimating capacities on freeway work zones in Florida. The current methods have not been modified since 1995, and the FDOT is particularly interested in new ways to facilitate the scheduling and managing of lane closures. This thesis proposes new simulation-based models for estimating the capacity of a temporary freeway work zone lane closure. Some of the factors considered in model development include the location of the upstream warning sign, the presence of trucks, the presence of law enforcement and/or heavy equipment, and the length of the work zone. In addition to these inputs, the average speeds per vehicle and the vehicular lane distributions for specific network links were considered in model development. A large matrix of scenarios was created so that the effects of all combinations of factors could be observed. Data were collected from simulation of these scenarios using the software package CORSIM 5.1. Three lane closure configurations (2-to-1, 3-to-2, and 3-to-1) were simulated and one model for estimating capacity was developed for each. All models for each lane closure configuration consider the input factors named previously as well as average speeds per vehicle and lane distributions of vehicles upstream of the work zone lane closure. The final models show the effects of each of these factors on the throughput capacity of a freeway lane closure. A higher fraction of vehicles in the to-be closed lane(s) prior to the work zone leads to a significant decrease in capacity. Likewise, higher speeds in the to-be closed lane(s) also lead to a capacity decrease. The result of this simulation modeling offers valuable insights into the relative capacities under different geometric configurations and traffic stream scenarios. Future research is recommended to calibrate the models to actual field conditions.