California Partners for Advanced Transportation Technology

Understanding the benefits of improved traffic flow (reduced congestion) is critical to the assessment of investments in infrastructure or traffic management and control. Improved flow should lead to reductions in travel time, vehicle emissions, fuel usage, psychological stress on drivers, and improved safety.    However, the manner in which safety is improved by smoothing traffic flow is not well understood. The documented research is aimed at shedding light on the complex relationships between traffic flow and traffic accidents (crashes).