Network performance models could also be used to compare traffic conditions among different cities in order to determine the allocation of resources for transportation system improvements. Chapter 7 addresses traffic impact models. Issues of traffic safety and environmental impacts, such as fuel consumption and air pollution, were not specifically addressed in the previous monographs. Traffic safety is always the number one issue when dealing with traffic operations and management, and since the Clean Air Act Amendments became law in 1990, fuel consumption and air quality have become critical issues when dealing with transportation and traffic management projects. Chapter 8 is on unsignalized intersection theory.
Unsignalized intersections give neither positive indication nor control to the driver.
The driver alone must decide when it is safe to enter the intersection. At unsignalized intersections, the driver must also respect the priority of other drivers. It also discusses the intersections among two or more streams and provides calculations of capacities and quality of traffic operations based on queuing modeling. Chapter 9 discusses traffic flow at signalized intersections. The statistical theory of traffic flow is presented to provide estimates of delays and queues at isolated intersections, including the effect of upstream traffic signals.