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Defining Areas of Potential Effects: State of the Practice


Section 106 of the National Historic Preservation Act (Section 106) requires federal agencies to consider the effects of their projects, activities, and programs on historic properties. Transportation agencies must establish the Area of Potential Effects (APE), which is the geographic area within which a federal action has the potential to effect historic properties eligible or listed on the National Register of Historic Places. Linear transportation corridors, particularly those that cross municipal, state, and/or Tribal boundaries, present a particular problem when defining an APE. Accurately and effectively defining the APE is essential to determining the level of effort required for the project’s compliance with Section 106.

APEs are generally defined on a project-by-project basis, without a standard methodology by project type or common approach. This can result in lengthy discussions and deliberations between transportation agencies, state and local officials, Tribes, and other interested parties. An APE that is too narrow may not adequately capture all the project effects, and need to be adjusted later in the process. An APE that is too large may cause over expenditures in time and money for survey work. On large linear transportation projects, and APE that is too large or too small can easily set back project timelines with impact to funding and construction deadlines.

Across the Nation, there are transportation agencies, states, and organizations that have developed standard approaches on how to effectively establish APEs for projects. However, much of this information resides solely within its respective state or organization; there is no nationwide survey or database of solutions that others could look to for guidance.


There are a variety of methods, standards, and agreements in place to define APEs, but there is no one central repository or synthesis of best practices. This Research Needs Statement (RNS) proposes a comprehensive nationwide survey of State DOTs, FRA and other agencies as identified on establishing APEs for linear transportation projects, partnered with the creation of a document to discuss the survey findings and gather the best practices and/or methodologies currently in place. With this information, transportation agencies and project proponents could have access to examples and best practices that could immediately be useful. This RNS funding is needed to have a sufficiently wide reach and sample size, and to organize and synthesize the outcome.


A nationwide survey of practitioners and projects would bring to light the variety of approaches currently used to develop APEs for linear transportation projects.

Many agencies and individual practitioners struggle with the establishment of APEs for long linear projects, and do not have sufficient time, funding, or connections to reach out to a broad group of professionals to find existing solutions. This research would allow for a comprehensive nationwide survey to find the solutions and best practices already developed, house them in a central location, and create a report to serve as a reference on proven APE methodologies for the larger cultural resources and project management field.

For example, the survey research and subsequent report that would result from funding this RNS could be used to help agencies in negotiate APE delineation with partners and stakeholders by showing what industry standards are in setting APEs for certain project types. Best practices highlighted in the report could help agencies and officials by providing templates for how to incorporate these proven methodologies for development of APEs into reports and agreement documents.

The outcomes of funding this RNS would both foster more effective cultural resource compliance and improve project delivery.

Related Research:

A search for relevant topics in both TRID and RIP on 3.2.21 did not produce any results. There were a handful of Section 106-specific topics, but nothing relating to APEs.


Task 1: Nationwide Survey of Section 106 Practitioners

Major components of the survey:

  1. Create and implement a nationwide survey of Section 106 practitioners on their experiences delineating APEs for linear transportation projects.
  2. The survey would cast a wide net in soliciting information from a broad group of Section 106 practitioners. Practitioners could include: State Historic Preservation Officers and staff; Tribal Historic Preservation Officers and cultural resource staff; Federal Preservation Officers and cultural resource staff at federal agencies; cultural resource staff at state transportation agencies; cultural resource contractors working on transportation projects; and the Advisory Council on Historic Preservation staff.
  3. Potential survey questions/topics include:

    • Is establishing an APE a challenge in your work on linear transportation projects?
    • How is the APE defined in your agency/state/organization?
    • Who is involved in defining the APE? How are SHPO/Tribes involved?
    • What do you consider when thinking of “potential” to effect?
    • Do you have a documented methodology, approach, or agreement document where the process for establishing an APE is described?

Respondents who indicate they have examples of best practices, successful methodologies/documents, or other relevant information would receive a follow up interview. During this interview, specific information could be collected, including example or template documents.

Task 2: State of the Practice Document

Using the survey results and subsequent interviews from Task 1, this State of the Practice document would synthesize the current challenges, best practices, and practical advice for the delineation of APEs on linear transportation projects.

Major components of the document:

  • A synthesis of the responses to the survey, including a summary of the responses themselves.
  • A review/synthesis of documents currently in place around the country relating to APEs, and include example methodologies.
  • A list of best practices for practitioners to use when developing an APE or codifying a system on how APEs can be defined and could include examples from a range of undertakings, project types, and agencies.
  • Templates based on best practices captured in the survey for how to incorporate proven methodologies into agreement documents.

Potential impediments to implementation include a challenge in getting adequate representation from all of the relevant groups to participate in the survey. There may need to be support from agencies or organizations in the field to encourage participation. Ways to overcome this challenge will include keeping the initial survey brief and limiting detailed questions to follow-up interviews with those who indicate they have information to share. Survey participants will be encouraged using: the AME60 Committee to promote the survey to members and State’s Departments of Transportation; asking the National Council of State Historic Preservation Offices to promote the survey to members; and using available social media and list serves.


This State of the Practice document could immediately be useful to: - Federal transportation agencies, including cultural resource staff and project delivery staff - Federally-recognized Tribes, including cultural resource staff and transportation staff - State transportation agencies, including cultural resource staff and project delivery staff - Local transportation agencies, and local governments. - Cultural resource consultants, particularly those working on transportation projects - Advisory Council on Historic Preservation

The following TRB Committees: o AEP70 Environmental Analysis and Ecology o AME30 Native American Transportation Issues

Sponsoring Committee:AME60, Historic and Archeological Preservation in Transportation
Research Period:12 - 24 months
Research Priority:Medium
Source Info:AME60 RNS Development Team (state and federal transportation agencies)
Date Posted:10/05/2021
Date Modified:10/19/2021
Index Terms:Historic preservation, Historic sites, State of the practice, Construction projects,
Cosponsoring Committees: 

Please click here if you wish to share information or are aware of any research underway that addresses issues in this research needs statement. The information may be helpful to the sponsoring committee in keeping the statement up-to-date.