Identify an assessment method to determine regional cumulative impacts.  Identify what are cumulative impacts in both spatial (region) and timeframe (horizon- year) terms.  Develop sample matrix or other tools to identify what is appropriate analysis for different situations.

TERI Administrator Note (June 2007): Research Need Met

Research for the AASHTO Standing Committee on the Environment. Task 11. Secondary/Indirect and Cumulative Effects Analysis
http://www.trb.org/NotesDocs/25-25%2811%29_FR.pdf

The objective of this study is to review, summarize and evaluate statutory and regulatory requirements and implementing guidance related to assessment and mitigation of secondary/indirect and cumulative impacts of transportation projects.

Colorado DOT, Areawide Coordinated Cumulative Effects Analysis (Research Underway)

Within a metropolitan planning region, there are a number of issues pertinent to a cumulative environmental effects analysis common to a number of individual NEPA-compliant documents. Conducting individual cumulative effects evaluations within the same area of impact is redundant and a waste of resources. The product of this study will facilitate the preparation of project-level environmental documents and should generate substantial savings in terms of time and money for the participating and affected agencies.