Cellular automata models play an important role in traffic modeling. For some variants of the Nagel-Schreckenberg model, the effects of traffic light boundary conditions are considered. Based on previous results, the exact density profiles can be derived easily for deterministic dynamics. Additionally, the exact average outflow per traffic light cycle is presented not only in the deterministic case, but also for an important semi-stochastic variant with slow-to-start behaviour. Thereby, the models are strongly related to the well-known totally asymmetric simple exclusion process (TASEP) which can be regarded as a generic model for many driven particle systems.