This handbook is intended to assist practitioners in assessing indirect effects and cumulative impacts in the evaluation of transportation projects under the National Environmental Policy Act (NEPA). Issues covered in this handbook include: Understanding the definitions of direct effects, indirect effects, and cumulative impacts; gathering the information needed for the analysis; deciding the appropriate scope and level of detail; carrying out the analysis; identifying mitigation opportunities; documenting the analysis; and using the transportation planning process to support NEPA-level studies of indirect effects and cumulative impacts.

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Handbook Resources

CEQ Guidance

CEQ, “Forty Most Asked Questions Concerning CEQ’s National Environmental Policy Act Regulations” (March 16, 1981)
http://ceq.hss.doe.gov/nepa/regs/40/40p3.htm

CEQ, “Considering Cumulative Effects under the National Environmental Policy Act” (1997)
http://ceq.hss.doe.gov/nepa/ccenepa/ccenepa.htm

FHWA Guidance

FHWA, “Questions and Answers Regarding the Consideration of Indirect and Cumulative Impacts in the NEPA Process” (2003)
http://www.environment.fhwa.dot.gov/strmlng/newsletters/may03nl.asp

NCHRP Reports

NCHRP Report 403, “Guidance for Estimating the Indirect Effects of Proposed Transportation Projects” (1998)
http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=742

NCHRP Report 466, “Desk Reference for Estimating the Indirect Effects of Proposed Transportation Projects” (2002)
http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=741

NCHRP 25-25 Task 43, “Legal Sufficiency Criteria for Adequate Indirect Effects and Cumulative Impacts Analysis as Related to NEPA Documents” (2008)
http://144.171.11.40/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=761

State DOT Guidance Documents

California DOT, “Guidance for Preparers of Cumulative Impact Analysis” (2005)
http://www.dot.ca.gov/ser/cumulative_guidance/approach.htm

California DOT, “Guidance for Preparers of Growth-related, Indirect Impact Analyses” (2006)
http://www.dot.ca.gov/ser/Growth-related_IndirectImpactAnalysis/gri_gu
idance.htm

Florida DOT, “Cumulative Effects Evaluation – Quick Guide” (Dec. 2012)
http://www.dot.state.fl.us/emo/pubs/CEE/CEE-QuickGuide-2012-1218.pdf

Maryland State Highway Administration, “Indirect and Cumulative Effects Analysis Guidelines (2007)
http://www.sha.state.md.us/OPPEN/ICE-Introduction.pdf

Montana DOT, “Assessing the Extent and Determinates of Induced Growth” (2013)
http://www.mdt.mt.gov/research/projects/planning/growth.shtml

Ohio DOT, “Guidance on Indirect Effects and Cumulative Impacts Analyses” (2014)
https://www.dot.state.oh.us/Divisions/Planning/Environment/NEPA_policy
_issues/Documents/ODOT%20ICE%20Guidance%20(FINAL%20version).pdf

Pennsylvania DOT, “Indirect and Cumulative Effects Guidance (2008)
http://www.dot.state.pa.us/public/PubsForms/Publications/PUB%20640.pdf

Texas DOT, “Environmental Handbook Indirect and Cumulative Impacts” (2014)
http://www.txdot.gov/inside-txdot/division/environmental/compliance-to
olkits/impacts.html

Washington State DOT, “Guidance on Preparing Cumulative Impact Analyses” (2008)
http://www.wsdot.wa.gov/Environment/Compliance/techguidance.htm#Cumulative

Wisconsin DOT, “Guidance for Conducting an Indirect Effects Analysis” (2007)
http://www.dot.wisconsin.gov/localgov/land/effects.htm