ABSTRACT
Now, traditionally, traffic experts have operated with one objective: to move people into and around cities as rapidly and efficiently as possible. For urban and suburban arterials, they are a simple function of average travel speed. For other types of roadways, the relationship to speed is less direct but no less germane. Once a roadway’s design speed is set, levels of service become a simple function of average travel speed. The federal Clean Air Act Amendments of 1990 require states to develop plans for attaining national air quality standards in polluted areas. Mobility is being viewed, for the first time, in a multimodal context. The aggregate volume of travel is being treated, for the first time, as something to be minimized rather than maximized. Development of a unified performance measurement system starts with a systemwide goal. All terms on the right-hand side of this equation are performance measures.
