Lane closure operations in highway work zones use both slow lane closures (SLCs) and fast lane closures (FLC), requiring drivers to perform two different merging maneuvers. While the merging location of vehicles can derive valuable insights on driver merging behavior, there is limited understanding available in the literature about merging locations in these two types of lane closures. To address this gap, this paper presents results from an observational study of two work zones in New South Wales, Australia. Videos of merging events were collected from a SLC and a FLC and processed using an automated image processing tool to compare the merging locations of vehicles in these two setups. The effects of vehicle type and platoon characteristics on merging locations were analyzed using descriptive statistical analysis. The results showed that late merging cases were more common at SLC compared to FLC. Type of merging vehicle, order of merging vehicle in platoon, and the type of leading vehicle were found to significantly influence the merging location of SLC, while order in platoon was not found to be a significant factor for FLC. These findings suggest that the type of lane closure configuration should be considered in the design of temporary traffic controls to ensure safe and efficient merging events.