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Transportation Conformity Practices in Complex Areas

Nonattainment and Maintenance Areas with

There are 32 nonattainment or maintenance areas where the nonattainment or maintenance area boundary is larger than the MPO(s) planning area, and therefore, contains a "donut area." Donut areas are geographic areas outside a metropolitan planning area boundary, but inside the boundary of a nonattainment or maintenance area that contains any part of a metropolitan area(s). These areas are not isolated rural nonattainment and maintenance areas.

These areas include 43 MPOs as shown in Attachment C. To demonstrate conformity of projects in the donut portion, such projects must have been included in the regional emissions analysis that supports the conformity determination of the MPO's plan and TIP. Challenges these areas face include:

SIP issues - such as how the motor vehicle emissions budgets are developed and whether sub-area budgets are utilized.

Institutional Arrangements - such as which agency takes the lead on analysis for the donut area portion of the nonattainment/maintenance area. Also, a non-MPO planning entity or municipality (i.e. regional planning council) often has planning responsibilities within the donut area. In such cases, the non-MPO planning entity should be engaged in an interagency consultation and/or participate in data collection and analysis.

Analysis issues - such as how the regional emissions analysis is conducted, and how the results can be combined if a separate analysis is conducted for the donut area.

SIP Issues:

In order to develop a motor vehicle emission budget for the SIP, emissions for the entire nonattainment or maintenance area, including any donut area, must be estimated. Areas must determine how to calculate vehicle activity and associated emissions in the donut area, where limited data may exist. Interagency consultation should be used to ensure that travel and emissions assumptions and calculations in the donut area are consistent with those in the metropolitan area.

In addition, States may wish to consider the use of sub-area budgets in these areas. If an area decides to create a sub-area budget for the donut area, the SIP would have to explicitly indicate that sub-area budgets have been created and would have to explicitly show the sub-area budgets for each portion of the nonattainment or maintenance area. Eight of these nonattainment and maintenance areas with donut areas are also Multi-MPO Nonattainment and Maintenance Areas (see also Attachment B):

Ten of these areas are also Multi-State Nonattainment and Maintenance Areas (see also Attachment A):

Institutional Arrangements:

The conformity rule requires that the interagency consultation process include specific procedures when the metropolitan planning area does not include the entire nonattainment or maintenance area. The process should engage the MPO and the State DOT in cooperative planning and analysis for purposes of determining conformity of all projects outside the metropolitan area, but within the nonattainment or maintenance area.

Regardless of which agency takes the lead, once the decision is made as to which agency will perform the emissions analysis for the donut area, an agreement must be developed to outline the roles and responsibilities of the MPO, the State DOT, and possibly others (e.g., the State air agency or the jurisdiction(s) that lie within the donut area). The agreement is intended to facilitate regional emissions analysis in these areas and to clearly state which agencies are involved in the analysis and their respective roles.

In 17 of these nonattainment/maintenance areas with donut areas, the MPO takes the lead in conducting the regional emissions analysis for the donut area (noted in Attachment C):

These MPOs typically represent larger metropolitan areas that have the staff capacity and resources to include the donut area in the regional emissions analysis.

For example, in the Atlanta, Georgia metropolitan area, the Atlanta Regional Council (ARC) conducts travel and air quality modeling for 1997 8-Hour Ozone for parts of counties outside the ARC planning area (portions of Spalding, Walton and Barrow Counties). Over time ARC expanded their travel model to encompass the donut areas. In the process they created a series of MOUs with the three counties they model for air quality stating that they would handle the technical analysis work for the nonattainment conformity demonstrations.  The state DOT and Air Agency have signed off on these MOUs. At every major milestone, representatives from the three counties participate in the development of the Regional Transportation Plan RTP and TIP.

The donut area associated with the Salt Lake City nonattainment area (2006 PM2.5) represents a transitional case due to a recent redefinition of the MPO’s boundary. In this case, the MPO, the Wasatch Front Regional Council (WFRC), has a former donut area in Brigham City/Box Elder that was designated as part of the MPO planning area in 2012. However, the area had not (as of May 2013) been incorporated into the WFRC travel model. In the interim, Utah DOT is preparing Vehicle Miles Traveled (VMT) estimates for Brigham City/Box Elder, and supplies these data to WFRC for input to MOVES. WFRC prepares the emissions estimates for the entire region, inclusive of Brigham City/Box Elder, using MOVES.

The Columbus, OH 8-hour ozone nonattainment area contains portions of Knox and Madison Counties, which are outside both MPO planning areas. This nonattainment area is also a multi-MPO area, involving the Mid-Ohio Regional Planning Commission (MORPC) and the Licking County Area Transportation Study (LCATS). For this nonattainment area MORPC provides information for the MORPC planning area and for the donut areas to Ohio EPA, which is the lead agency for coordinating the development of the State Implementation Plan (SIP). Whenever there are issues that might affect multiple MPOs, a larger group may be convened. In addition to Ohio EPA other participants include the Ohio Department of Transportation, Ohio Environmental Protection Agency, the US Environmental Protection Agency, the Federal Highway Administration, and the affected MPOs. MORPC and the Licking County Area Transportation Study (LCATS) have an MOU with Ohio EPA and ODOT that establishes the roles and process in conducting a conformity analysis.

In fifteen nonattainment and maintenance areas with donut areas, the State DOT takes the lead for regional emissions analysis for the area that falls outside of the MPO planning area. This is also noted in Attachment C. An example of this is in the State of North Carolina, which contains the Charlotte-Rock Hill, NC-SC nonattainment area for 8-hour ozone (2008 standard).

This nonattainment area is a particularly interesting multijurisdictional area representing a multi-state (NC, SC) and a multi-MPO, with a donut area. The MPOs involved are:

For this nonattainment area a process has been developed between the State DOT and each of the four MPOs on how the analysis should be completed. In short, the MPOs, with assistance from the State DOT, take the lead on regional emissions analysis for the metropolitan portion of the areas, and the State DOT conducts the regional emissions analysis on the donut portions. The emissions from the MPO and State DOT analyses are then summed to determine conformity. The MPOs' conformity determinations on transportation plans and TIPs are then based on this result, as are any project-level conformity determinations in the donut area.

In several cases, the DOT will prepare VMT estimates for the donut area and the MPO will use these estimates in emissions modeling. Other variations on analytical approaches occur when a state air agency, such as an Air Quality Management District in California, will conduct the emissions analysis for the donut area. An example of this case is the Tuscan Buttes 8-hour ozone (2008 standard) nonattainment area. For this case, the California Air Resources Board works with the Tehama County Air Pollution Control District to prepare the travel and emissions.

Analysis issues:

Close coordination should occur between the MPO and the State DOT and/or jurisdictions within the donut area adjacent to the MPO. Many MPOs with donut areas use the interagency consultation process as the forum to develop agreement on planning assumptions used in the conformity process. Some areas do not have a formal schedule in place for updating planning assumptions. Typically there is an ongoing interagency consultation process conducted on an as-needed basis, often through emails or phone calls. An example of the latter is the Atlanta Regional Commission which updates planning assumptions on an ongoing basis and conducts a conformity analysis once per year, on average. In other cases MPOs update planning assumptions every 3 to 5 years.

Typically, motor vehicle emissions budgets are calculated for the entire Nonattainment area, inclusive of the donut areas. The arrangement with ARC conducting the analysis for the donut areas has been in place for several years and, as stated previously, ARC’s travel model has been incrementally expanded to include the donut areas. However, there is one donut area for the PM 2.5 1997 annual standard where ARC staff conducts an off-model calculation, obtaining traffic activity inputs from the State DOT for running MOVES.

Another common arrangement is for one agency, the MPO or State DOT, to prepare the travel activity data as input to the emissions analysis conducted by the other agency. An example of this arrangement is for the Columbus, OH 8-hour ozone (2008 standard) donut area. For this case the MORPC takes the lead on the travel demand analysis using HPMS data to establish base year VMT. VMT growth is established with Ohio DOT. ODOT runs MOVES and provides emission factors by facility type and speed. Other technical issues to be ironed out include analysis years, interim years, changes in fuel requirements, as well as changes involving the use of MOVES. The alternative approach is illustrated by the St. Louis, MO-IL 8-hour ozone (2008 standard) nonattainment area. For the donut area in Illinois, the Illinois DOT provides VMT estimates to the East-West Gateway Council of Governments who in turn conducts the emissions analysis.

Updated: 10/20/2015
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