Speed characteristics are influenced by many different factors (e.g. road engineering, vehicle classification, temporal factors, and weather factors) and in turn influence various outcomes such as safety, environmental impacts, and road user costs. In order to work towards improved outcomes in these areas, it is important to understand current speed characteristics and how these characteristics vary with influencing factors. The research leading to this paper had two objectives: (1) to synthesize existing knowledge about speed and factors that either influence speed or are an outcome of speed, and (2) to analyze speed data to determine the vehicle operating speed impacts from different vehicle classifications, temporal factors, environmental factors, and road factors. The literature review conducted for the synthesis of existing knowledge examines selected publications from the last 10 to 15 years. The speed data is obtained from the Manitoba Highway Traffic Information System (MHTIS) database from five weigh-in-motion (WIM) devices on selected portions of Manitoba’s National Highway System (NHS) roads. This database contains nearly continuous year round information and approximately eight million geographically referenced speed records linked to vehicle classification and time of day for the year 2010. The speed records from the five WIM devices are aggregated together to determine the distribution of vehicle speeds with respect to different influencing factors including: (1) vehicle classification (motorcycles, passenger vehicles, small trucks and buses, single trailer combinations, and multi-trailer combinations), (2) temporal factors (seasonal, monthly, day of week, and time of day), (3) environmental factors (lighting and weather factors), and (4) road engineering factors (divided and undivided highways, and urban and rural highways). The results of the analysis provide a better understanding of speed behaviour under different influencing factors.