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Transportation Conformity Practices in Complex Areas

MPOs with Multiple Nonattainment or Maintenance Areas for the Same Pollutant

There are 21 MPOs in 15 States as shown in Attachment D that contain more than one nonattainment and/or maintenance area, or portions of such areas, for the same pollutant. MPOs may be in nonattainment for more than one pollutant (i.e., ozone and CO); however, this discussion does not focus on those areas. MPOs with multiple nonattainment or maintenance areas for the same pollutant face special challenges that include:

SIP Issues:

Different SIP requirements may apply to each nonattainment or maintenance area depending on the classification of the area. For example, higher classified ozone areas are subject to more stringent control measures such as enhanced inspection and maintenance programs and potential transportation control measures, while a lower classified area may not be subject to those measures. Different classifications can also complicate the conformity process several ways. For example, different SIP submission or revision schedules for each nonattainment or maintenance area may result in different conformity determination triggers that the MPO must comply with, as well as different attainment and/or milestone years. Also, the motor vehicle emissions budgets may be based on different versions of the MOBILE model for each nonattainment or maintenance area.

MPO regional emissions analyses must be consistent with the motor vehicle emissions budgets in SIPs. In many cases, each nonattainment and maintenance area may have its own budget. However, nonattainment and maintenance areas may contain sub-area budgets. In those cases, the regional emissions analyses must be consistent with the appropriate sub-area budgets.

Budgets for separate nonattainment/maintenance areas cannot be combined in the conformity process by the MPO. However, the State and local air agencies, in the development of the SIP, may choose to combine inventories within a metropolitan area for different nonattainment/maintenance areas and develop a single motor vehicle budget in the SIP for the MPO. In this case, where the SIP identifies a "combined" budget, the MPO may demonstrate conformity for this single budget. New Jersey utilizes this method:

There are 4 1-hour ozone nonattainment areas, or portions of such areas, within the State of New Jersey (a portion of the Allentown-Bethlehem-Easton, PA-NJ area, a portion of the New York-N. New Jersey-Long Island, NY-NJ-CT area, the Atlantic City, NJ area, and a portion of the Philadelphia-Wilmington-Trenton, PA-NJ-DE-MD area). However, instead of identifying emissions budgets along nonattainment area boundaries, the State's SIP instead allocated specific emissions budgets to each of the three MPOs, or portion of which, that are within the State (the Delaware Valley Regional Planning Commission, the North Jersey Transportation Planning Authority, Inc., and the South Jersey Transportation Planning Organization.)

Also, it should be noted that conformity for each nonattainment and maintenance area can be determined separately. For example, if an MPO contains multiple nonattainment areas, but cannot demonstrate conformity for one of the areas, it can still determine conformity for the other area(s).

In addition, 11 of the MPOs in this category only contain a portion, or portions, of a nonattainment or maintenance area or areas that encompass other MPOs as well. In other words, these 11 MPOs are also part of Multi-MPO Nonattainment and Maintenance Areas (see also Attachment B). Further more, 7 of these 11 MPOs are part of Multi-State Nonattainment and Maintenance Areas (see also Attachment A).

Another issue occurs when the nonattainment or maintenance areas is larger than the MPO planning area and therefore includes a donut area. 4 of the MPOs in this category are part of nonattainment or maintenance areas with donut areas. For more information, please see Nonattainment and Maintenance Areas with "Donut" Area(s) and Attachment C.

Institutional Arrangements:

Where multiple nonattainment or maintenance areas are within the planning boundaries of a single MPO, there may be multiple air agencies that must be part of the interagency consultation process. About half of the MPOs have monthly interagency consultation meetings in order to facilitate coordination. The other MPOs hold interagency consultation meetings as needed, with no fixed schedule. We found that the principle reason interagency consultation works in these areas is because it encourages ongoing communication among the key partners. The following are some examples of institutional arrangements and tools that assist in interagency consultation:

The El Paso MPO has a pre-analysis consensus plan which helps make the process work. This pre-analysis consensus plan is used in other areas of Texas, and we found it greatly assists in the planning activities of MPOs and helps them anticipate resource needs.

In Pennsylvania, an annual pre-conformity analysis meeting for all MPOs impacted by conformity is held to coordinate schedules and ensure roles and responsibilities are clear. This process has worked well for the State DOT and MPOs and has the added benefit of ensuring consistency in how all conformity determinations in the State are conducted.

Most of the MPOs with multiple nonattainment/maintenance areas are subject to conformity SIPs that include interagency consultation procedures. These include, for example:

In general, the States and MPOs in this category have not established formal synchronized planning clocks for transportation and air quality but the MPOs and State DOTs tend to work together to establish the schedules for transportation plan updates, TIP updates, and conformity determinations.

Analysis issues:

Decisions about which agency takes the lead on travel and demand modeling need to be made as well as coordination on schedules for updating assumptions. A key scheduling issue is keeping the timelines for conformity straight for each of the nonattainment or maintenance areas within the MPO area. SIP submittals should be coordinated through interagency consultation with the MPO so that conformity determination triggers can be anticipated and appropriately planned for.

As noted in Attachment D, in 11 of MPOs with multiple nonattainment and/or maintenance areas, the MPOs take the lead for both travel demand and emissions modeling. In 5 of these areas, the MPOs take the lead on travel demand modeling, and the State DOT takes the lead on emissions modeling. In 4 of these areas, the MPOs take the lead on travel demand modeling, and the State air agency takes the lead on emissions modeling. And finally, in 1 of these areas, the State DOT takes the lead on both travel demand and emissions modeling.

Updated: 07/06/2011
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