This report describes the transportation planning process and discusses where and how environmental factors can be addressed effectively at the state and metropolitan levels. This report should be especially useful to federal, state DOT, MPO, and local transportation planners, as well as other practitioners concerned with addressing environmental factors within transportation systems planning, priority programming, and project development planning leading to implementation. Transportation systems plans provide the basis for selecting and developing transportation projects. However, because of their long time frames and broad scopes, systems plans often are developed without detailed consideration of how plan implementation will affect the built and natural environment. This creates problems in that some important projects may be very difficult, if not impossible, to implement because of environmental consequences that could have been identified, considered, and possibly avoided much earlier in the planning process. Furthermore, insufficient consideration of environmental factors in transportation systems planning may cause decision makers to miss opportunities to adopt plans that are fully consistent with statewide and regional environmental goals and to implement larger scale environmental mitigation and enhancements. Typically, environmental factors are more closely examined during project development and, in some cases, during corridor or subarea planning. Federal and state law and sound planning practice call for considering environmental factors within the development of transportation systems plans. However, few processes, procedures, or analysis methods are generally accepted for considering environmental factors in transportation systems planning. In addition to “fatal flaw” analyses, other environmental considerations are more appropriately addressed at the systems planning level. These include purpose and need determinations, areawide air- and water-quality impacts, ecosystem analysis, watershed evaluations, secondary and cumulative impacts, and social and community impacts. Although cost-effective, macro-scale analysis methods, such as GIS applications and air-quality modeling, could be used to develop and evaluate systems plans, these and other methods are not applied widely in systems-level transportation planning. If elements of transportation systems plans are to proceed through project development to implementation, systems-level environmental considerations must be addressed earlier in planning. The objective of this research was to identify, develop, and describe a process, procedures, and methods for integrating environmental factors in transportation systems planning and decision making at the statewide, regional, and metropolitan levels. The research focused on environmental issues within the long-range transportation planning processes of state DOTs and MPOs and included the following: (1) a comprehensive review of recent literature; (2) a survey of approaches employed by DOTs, MPOs, and environmental regulatory agencies; (3) a review of federal regulations and guidance on environmental factors; and (4) case studies to synthesize current practice in environmental planning. A planning process was developed that describes how and when various methods can best be applied in developing systems-level transportation plans. The process addresses decision-making relationships; technical requirements (e.g., data and analytical methods); necessary staffing capabilities; public involvement; interagency coordination; financial commitments; and methods for tying the systems planning considerations to more detailed processes such as corridor planning, subarea planning, modal development planning, priority programming, and project development. Under NCHRP Project 8-38, “Consideration of Environmental Factors in Transportation Systems Planning,” the Georgia Institute of Technology in Atlanta, Georgia, reviewed current practice in dealing with environmental issues within the state and metropolitan transportation planning processes. The report describes procedures, methods, and institutional arrangements for successful consideration of environmental factors in transportation planning. The report also presents a broad framework for assessing, evaluating, and integrating environmental issues and concerns into systems-level transportation planning and decision making. Detailed supplementary information on relevant regulations and guidance and the results of the project survey are presented in NCHRP Web-Only Document 77. (Author/publisher) This report may be accessed by Internet users at http://gulliver.trb.org/publications/nchrp/nchrp_rpt_541.pdf
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