Dependable vehicle-to-infrastructure (V2I) communication links for intelligent transportation systems are aimed at improving traffic safety and efficiency. The future integration of such cooperative systems, in particular in urban environments with challenging propagation conditions, requires adequate deployment of roadside units (RSU). To analyze the joint impact of typical urban characteristics and RSU deployment conditions on the quality of IEEE 802.11p V2I communications, an extensive measurement campaign was performed in Bologna as part of the European FP7 project iTETRIS. Based on the measured data, we identify specific street layouts and propagation impairments, and we estimate the parameters of a previously introduced range-dependent modified Gilbert model. The resulting set of model parameters enables the generation of realistic packet error patterns for any comparable urban environment.