Improvement of air quality by means of transportation system management

Under the United States federal Clean Air Act Amendments of 1977, states must implement transportation system management (TSM) tactics in urban areas that have not attained national ambient air quality standards for carbon monoxide and photochemical oxidants. This paper provides a preliminary assessment of the effectiveness and feasibility of using TSM tactics to improve air quality. Based on this assessment, the authors conclude that TSM measures should be effective in eliminating localized carbon monoxide problems, but that such measures are not likely to contribute significantly toward reducing regional oxidant levels. In addition, because most individual TSM tactics can have only marginal impacts on regional motor vehicle emissions, coordinating the planning and implementation of a portfolio of TSM measures will be an essential element of an effective TSM program for improving air quality.