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NEPA 404 MOU Guidance (Part 1)


Purpose and Need
Alternatives Analysis and Aquatic Resource Avoidance Guidance for Transportation Projects
Compensatory Mitigation
Level of Data Needs / Threshold for Involvement


"Purpose and need" is a critical element of the transportation planning, project programming, and project development stages because it performs two important functions: § It establishes why the sponsoring agency is proposing an action while at the same time potentially causing environmental impacts, and § It provides the basis for selecting reasonable and practicable alternatives for consideration; analyzing those alternatives in depth; and is an important factor in selecting the preferred alternative. If the project purpose and need is defined to meet the above two functions, section 404 requirements related to defining the project purpose will be satisfied. Under the National Environmental Policy Act (NEPA), "purpose" and "need" are closely linked but subtly different. "Need" may be thought of as the problem and "purpose" as an intention to solve the problem. Purpose and need statements should include increasing specificity as one progresses from transportation planning to project programming to project development. However, it is important to guard against premature specificity such that the range of alternatives considered becomes artificially limited. Expressions of purpose and need must reflect statutory and regulatory requirements, fiscal and environmental resources, and community concerns. The identification of purpose and need (e.g., degree of congestion used as a goal in planning and designing transportation facilities) is an administrative process of high importance at all stages. Both the purpose and need, and the factors contributing to their identification, must be clearly documented in a manner acceptable to the owner/operator. If the purpose and need deviates from the usual and expected practice (i.e., from project performance and/or design criteria), the owner/operator may be called upon in the future to rely on this documentation to defend against tort liability actions. For example, the degree of congestion that users are called upon to endure must reflect the available fiscal resources and a balancing of the desires of the users with the environmental/socioeconomic impacts of satisfying these desires. Freeways and arterials should normally be planned and designed to accommodate estimated traffic 20 years after completion of construction at a level of service at least equal to "C." However, a community based planning process may select a lower level of service goal in consideration of available fiscal resources and environmental impacts with appropriate documentation.



The regional transportation planning process, which includes systems, subarea, and corridor planning, should establish transportation goals and objectives for all major transportation investments. The transportation goals and objectives for systems and corridors are analogous to a statement of purpose under NEPA. A regional planning needs statement should clearly document a problem or short-fall in meeting goals and objectives. Initially the purpose statement should be a general goal, such as to reduce congestion, improve safety, increase mobility, or to reduce pollutant emissions, so as to allow consideration of a range of alternative means to achieve the basic project purpose. The statement of purpose should not be so narrow as to preclude a reasonable range of alternatives from consideration. A narrow initial statement of purpose unnecessarily reduces the decision makers' flexibility to balance competing requirements. The need for transportation projects should reflect the regional transportation plan's policies and should be expressed in terms of congestion, safety, or air quality, for example. Need should be quantified, providing a measure of the severity and geographic extent of the problem. For example, need could be expressed as a quantified short-fall in meeting defined regional objectives, such as those for mobility, accident frequency and air quality. Documentation should be clearly summarized and referenced within the statement of need. Full documentation (in the form of studies, reports, etc.) should: § include references in the statement of need, § follow the project through the entire programming, development and construction process, and § be readily available upon the request of reviewing agencies (transportation and resource agencies). Products of the transportation planning process (such as reduction in vehicle-kilometers or vehicle-hours of travel, improvements in travel speeds on the system, reduction in traffic accidents, savings in energy consumption, enhanced economic development potential, increased tax base, improved access to public facilities, etc.) should be presented to support the need for the transportation investment. This purpose and need will serve as the basis for establishing the range of alternatives (such as alternative modes and technologies) to be considered during the transportation planning process (which may include corridor or subarea studies). These studies will ultimately determine project design concept and scope for the emissions analysis of the regional transportation plan required by EPA conformity regulations. Even though a need may be easily established one should also consider the constraints of meeting this need, such as the presence of section 4(f) protected property (49 U.S.C. § 303), waters of the U.S. (see glossary), floodplains, endangered species, and historical properties. The purpose statement should guide the range of alternatives that will be considered to respond to the established need. For example, responding to the need for access to the downtown of a metropolitan area could generate alternatives such as transit and feeder projects. Likewise, the need to improve highway safety may result in alternatives to reroute truck traffic, improve geometrics, or bypass or widen existing facilities.


When a project identified in a regional transportation plan (RTP) is about to undergo a preliminary study (i.e., project assessment in Arizona and Nevada; project study report in California), the goals, objectives, and policies of the RTP will provide the foundation for defining the project purpose and need statement. As information is developed and more is learned, the purpose and need statement would be refined. During this refinement process, some project alternatives could possibly drop out (see Alternatives Analysis / Aquatic Resource Avoidance Guidance), thereby permitting a more focused analysis of the remaining alternatives. Need must be defined more specifically at this stage to support project programming. For those projects which are not part of a regional transportation plan or for which no purpose and need have previously been established, the guidelines discussed above under Transportation Planning should be followed before project programming.


The need for a project must be very specific at this point in the process. Information gathered during the transportation planning and project programming stages should ensure that the project need is well defined. It is critical that the process which identified and quantified this specific need be explained clearly and concisely within the NEPA environmental document, with specific references to previous studies. If the need is modified, sufficient data to document the changed circumstances should be provided. The purpose and need statement at this stage should provide the framework for considering the avoidance or minimization of environmental impacts and any enhancement of environmental resources in the project area. Sufficient information should be available at this stage to consider all reasonable alternatives that will satisfy the established need.





Ensure "purpose" is consistent with transportation goals and objectives (e.g., mobility, safety, capacity, and congestion relief)

Ensure "purpose" constitutes a reasonable expenditure of public funds (benefit:cost)

Ensure "purpose" is broad enough to allow consideration of a full range of alternative ways to meet the defined need


Social Demands or Economic Development

  1. Discuss existing land use plans
  2. Identify projected land use plan changes
  3. Identify growth management/control ordinances
  1. Modal Interrelationships Discuss project interface with airport, rail, port, and mass transit facilities

  2. Capacity, Transportation Demand, and Safety

    1. Describe existing capacity and level of service
    2. List regional population/traffic forecasts
    3. Identify projected capacity needs and level of service
    4. Identify system safety needs
  3. Air Quality Improvements

    1. Identify transportation control measures (e.g., high occupancy vehicle lanes, ramp metering, bike lanes, park & ride facilities)
    2. Identify transportation demand management (e.g., rideshare programs, mass transit subsidies)


  1. All of the project purpose and need information developed during the transportation planning stage must be carried forward, updated, and refined in the purpose and need discussion for the project programming stage (i.e., social demands or economic development, modal interrelationships, capacity and transportation demand, air quality improvements).
  2. the following additional information should be provided:
    1. Project Status
      1. Describe the history of the project (adopted corridors, land use plans, regional transportation plans)
      2. Describe the involvement of other agencies, including any previous planning, programming, or project concurrences/nonconcurrences
      3. Identify the actions pending (e.g., NEPA, final design, right-of-way acquisition, and permits)
      4. Provide the project schedule
    2. System Linkage
      1. Indicate whether the project is a "connecting link"
      2. Describe how the project fits into the transportation system
    3. Legislation Describe any Federal, State, or local government mandates (e.g., demonstration projects, sales tax measure projects)
    4. Safety
      1. Describe the existing accident rate
      2. Describe the projected accident rate with/without project
      3. Compare the existing and projected accident rates to statewide average
      4. Explain how the project will improve safety
    5. Roadway Deficiencies
      1. Describe operational deficiencies (substandard geometrics, inadequate cross-sections)
      2. Identify structural limitations (load limits)
      3. Discuss maintenance problems
      4. Explain how the project will correct deficiencies


All of the project purpose and need information developed during the project programming stage must be carried forward, updated, and refined in the purpose and need discussion for the project development stage (e.g., project status, system linkage, legislation, social demands or economic development, modal interrelationships, capacity and transportation demand, safety, roadway deficiencies, and air quality improvements).

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Page last modified on April 16, 2013
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