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The National Academies

NCHRP 08-36/Task 20 [Completed]

Conformity Problems Caused by the Mismatch in SIP / Transportation Plan Timeframe
[ NCHRP 08-36 (Research for the AASHTO Standing Committee on Planning) ]

  Project Data
Funds: 50000
Research Agency: Gary Hawthorn & Associates, Ltd.
Principal Investigator: Gary Hawthorn
Effective Date: 5/9/2001
Completion Date: 11/9/2002
Comments: Completed---Final report sent to AASHTO; $25K from Project 20-7/Task 141


Conformity must be demonstrated for the entire 20-year timeframe of the transportation plan, which extends well beyond the typical 10-year (or shorter) timeframe of SIPs or maintenance plans. Demonstrating conformity for the "outyears" of the transportation becomes increasing difficult because, over the longer term, VMT and emissions will continue increasing beyond the levels reflected in the vehicle emission budgets contained in the last year of the shorter term SIP / maintenance plan.

No adopted control measures are available, beyond those in the SIP or maintenance plan, to offset VMT / emission increases occurring in the outyears of the transportation plan. Also, MPOs generally lack the authority to adopt and enforce control measures. Therefore, the increased emissions associated with long-term growth must be offset solely by the transportation sector, mainly by the MPO, through the conformity process and changes to the transportation plan, rather than through the SIP or maintenance plan.

The proposed research will, through actual examples in specific areas, define and update the extent and severity of problems in demonstrating conformity due to the timeframe mismatch. The research will involve consultation (iterative discussions with all key stakeholders) that aims for a consensus on problems / causes / consequences. The research will then, through iterative consultation, aim for a consensus on different short and long term solutions (e.g., statutory provisions, amended regulations, and / or guidance.)

Sub tasks are the following:
  • Define conformity problems / causes / consequences due to the timeframe mismatch in varying ways and degrees of detail, using actual experiences in different areas, to effectively communicate these complicated issues to different officials, professionals, and stakeholders.
  • Discuss timeframe mismatch problems / causes / consequences with key conformity stakeholders and determine if a consensus can be reached. Identify areas of agreement and disagreement. Attempt, through iterative discussions, to narrow differences and achieve a consensus.
  • Identify and describe real life examples of ways in which timeframe mismatch problems have been addressed (e.g., the role played by different types of control measures). Assess the effectiveness of these measures and others. Identify and develop other options, both on the transportation and air quality side, including both different short and long term solutions (e.g., statutory provisions, amended regulations, and / or guidance).
  • Discuss possible timeframe mismatch solutions with key conformity stakeholders and determine if a consensus can be reached on a preferred solution(s). Identify areas of agreement and disagreement. Attempt to narrow differences and achieve a consensus on possible solutions through iterative discussions.

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