Transportation, particularly highway transportation, is a major contributor to emissions of greenhouse gases. Substantially curbing these emissions will require measures, such as fuel taxes, that would necessitate broad public understanding of the risks of global warming and support for considerably heavier taxes.

 The environmental regulatory process for considering new investments in infrastructure and establishing regulations for dredging involve multiple agencies with different missions and often take considerable time. Society would benefit from allocating resources to expedite these reviews in ways that would not sacrifice the quality of the analysis.

 The environmental regulatory process for determining compliance with national air quality standards places a great deal of emphasis on a technical modeling process that has many weaknesses. Reconsideration of the appropriateness of this approach is needed.

Environmental strategies that depend on managing land use involve multiple levels of government with differing goals and responsibilities, and their consequences require decades to unfold. Yet land use strategies can have highly significant effects over the long term.

Double-hull tankers have been effective in reducing oil spills. Models of tanker collisions and groundings can help the U.S. Coast Guard compare less expensive tanker designs that are claimed to be equally effective.

 Additional evaluation of transportation-related environmental programs could help make them more effective and less costly. Congressional reauthorization of the Congestion Mitigation and Air Quality Improvement program in 2005 adopted recommendations to improve project evaluation.