Motor Vehicle speeds Recommendations for Urban Sustainability

This paper explores how vehicle speeds are related to equitable, environmental, and economic sustainability of urban areas. This relationship is manifested primarily through associations between vehicle speeds and road crash casualties, severity of pedestrian crashes, generation of harmful emissions, and relative desirability of neighboring land. Reported research findings describing these associations are presented and discussed. Reported experiences with implementing various methods of influencing vehicle speeds, including automated enforcement, self-explaining roads, and in-vehicle systems, are presented and discussed. To support increased sustainability of urban areas, the following steps are recommended: (a) speed limits should be set to limit casualty risk and not to accommodate driver choices, (b) roadways in developed areas should be designed with 10-ft lanes and on-street parking and sidewalks, and (c) vehicle speeds in downtown and residential areas should be kept below 25 mph (preferably 20 mph). The paper also identifies gaps in knowledge about speed and sustainability