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Transportation Conformity Practices in Complex Areas

Multi-State Nonattainment and Maintenance Areas

There are 13 multi-State 1-hour ozone nonattainment or maintenance areas containing 37 MPOs, as shown in Attachment A. As part of multi-State areas, there are several unique challenges that these MPOs face in the conformity process. These challenges include:

SIP Issues:

Each State is responsible for developing its own SIP. Therefore, decisions are required between the States as to how motor vehicle emissions budgets will be developed for a multi-State nonattainment area. The States could choose 1) to develop SIPs for each State with a single common motor vehicle emissions budget for each pollutant/precursor for the entire multi-State area, or 2) to develop SIPs for each State with separate budgets for each State.

Following the first option, 3 multi-State areas decided to develop a single common budget for the entire multi-State area. In each of the MPOs within these three multi-State areas, conformity determinations are based on a regional emissions analysis done for the entire multi-State area and tested against the single budget. In other words, the motor vehicle emissions budget is not allocated among each State's portion of the nonattainment or maintenance area. Each State includes the same budget in its SIP for the entire nonattainment or maintenance area. These areas are also noted in Attachment A. Below is a more detailed example of one of these areas.

The Kansas City, MO-KS 1-hour ozone maintenance area encompasses three counties in Missouri and two counties in Kansas. The Mid-American Regional Council (MARC) is the MPO for this urbanized area, and its planning area includes all of the multi-State maintenance area. This area has been a maintenance area since 1992. The States have always included a single multi-State budget in their SIPs. Each time the MPO has determined conformity, a single regional emissions analysis has been conducted and tested against the single budget for the entire multi-State area. The most recent budget, the 2002 maintenance plan budget, was negotiated with all key stakeholders involved in the process. At the Mid-America Regional Council, the technical and policy members of the MPO represent both states and a very good working relationship exists between the States, the MPO, the FHWA Divisions offices in Missouri and Kansas, and the EPA Regional Office. (More about how the interagency consultation process works in this area)

In the other 10 of the multi-State areas, each State has separate budgets for its portion of the nonattainment or maintenance area. In other words, the States have negotiated allowable emissions for each State, and each SIP includes the motor vehicle emissions budget that applies to that State's portion of the nonattainment or maintenance area. MPO conformity determinations in these multi-State nonattainment and maintenance areas are based on separate regional emissions analyses for each State that are tested against the separate budgets for each State independently. Therefore, when each State has its own separate budgets, conformity for the portion of the multi-State nonattainment or maintenance area in one State does not depend on conformity in another State. Nonattainment and maintenance areas and States with separate motor vehicle emissions budgets are noted in Attachment A.

The St. Louis, MO-IL 1-hour ozone maintenance area encompasses five counties in Missouri and three counties in Illinois. The East-West Gateway Coordinating Council (EWGCC), the MPO for this urbanized area, covers the entire multi-State nonattainment area. The Illinois EPA and the Missouri Department of Natural Resources (DNR) developed separate motor vehicle emissions budgets for the portion of the maintenance area that falls within each State. EWGCC provides travel data to the Illinois EPA and Missouri DNR. For conformity, EWGCC conducts two separate regional emissions analyses using the Illinois budget and the Missouri budget, respectively. Then the EWGCC develops a table for inclusion in its conformity determination that shows the motor vehicle emissions budget for that portion of the area in each State. The Missouri DNR has been careful to work with EWGCC to ensure that the MPO is aware of and comfortable with the motor vehicle emissions budget for the Missouri portion of EWGCC's planning area. In previous years, a vehicle miles traveled (VMT) Workgroup was in place in Missouri to coordinate on the development of VMT estimates and projections. Further information on EWGCC's conformity determinations can be found at:

Institutional Arrangements:

The challenges of communication and coordination in multi-state nonattainment and maintenance areas increase due to the number of agencies and stakeholders involved in the transportation conformity process. Interagency consultation becomes critical in multi-State nonattainment and maintenance areas. This is especially true the first time through the SIP development and conformity processes when key decisions need to be made about motor vehicle emissions budgets and transportation-related control measures, and about how conformity determinations and regional emissions analyses are conducted.

In addition, 9 of these 13 multi-State nonattainment or maintenance areas also contain multiple MPOs. Attachment A also lists each MPO that is encompassed by each multi-State nonattainment and maintenance area. For the MPOs in particular, that have the final responsibility to make conformity determinations, coordination between the other MPOs and States is vital to a smoothly running process. This is aided by the fact that the majority of these areas have monthly interagency consultation meetings. The majority of these MPOs use the interagency consultation process to set the schedule for conformity determinations in each respective MPO area. However, most of these MPOs indicated that they do not have formally established schedules for conformity or planning document updates (i.e. TIPs/Plans) throughout the entire nonattainment area. This is because of the use of separate budgets for each State in these areas, which enable the MPOs within different States to remain independent in making conformity determinations.

The Portland -Vancouver AQMA, OR-WA 1-hour ozone maintenance area boundaries include both the Portland area MPO (Metro) in Oregon and the Southwest Washington Regional Transportation Council (RTC) MPO in Washington. Emissions assumed to originate within the Oregon and Washington portions of the area are independently calculated. Metro and RTC coordinate in development of the population, employment and VMT assumptions. (Memorandum of Understanding between Metro and RTC)

However, agreements are not common between the MPOs and States in entire multi-State areas, most of the MPOs have a formal agreement in place on how to make conformity determinations within their own planning area.

Analysis issues:

Planning assumptions - We also assessed multi-State area issues related to planning assumptions. We found that about half of the MPOs in these areas have a formal schedule for updating planning assumptions. We also found that there are several different approaches to updating planning assumptions in these areas.

Concurrence on planning assumptions is critical to a smooth, well-coordinated conformity process. In these multi-State areas, we found that 23 MPOs use the interagency consultation process as the forum where concurrence on planning assumptions occurs. Of these 23 MPOs, 8 MPOs require written concurrence, and 10 MPOs require oral concurrence.

An example of a formal process for approving planning assumptions is the Mid-America Regional Council in Kansas City, Kansas. The Mid-America Regional Council adopted a policy that requires the approval of planning assumptions by their Technical Forecast Committee and the Mid-America Regional Council Board prior to use in the long-range transportation plan. In addition, forecasts are available for public review and comment prior to presentation to the Regional Council Board for approval.

Travel demand and emissions modeling - We found that most MPOs in multi-State areas take the lead on travel demand and emissions modeling. However, there are variations to this approach. For example, six MPOs indicated that the State DOT takes the lead on travel demand modeling. Likewise, while the majority of MPOs take the lead on emissions modeling, ten MPOs indicated that the State DOT takes the lead on emissions modeling, and in one case, the local air agency takes the lead.

MOBILE6 - We also assessed whether MPOs in multi-State nonattainment and maintenance were using MOBILE6 for conformity purposes even though, at the time of the study, use of MOBILE6 was not yet required in all areas.

15 MPOs were already using MOBILE6 for conformity and 1 MPO said they are using both MOBILE5b and MOBILE6. This MPO, the Mid-America Regional Council, indicated that it was using both MOBILE5 and MOBILE6 to determine conformity to ensure that the Long Range Plan and TIP conform both to the not-yet-approved budget (MOBILE6-based) and the old budget (MOBILE5- based.)

15 MPOs were not yet using MOBILE6 for conformity at the time of the study.

Our assessment also indicated that 13 MPOs would transition to MOBILE6 by January 2004, the end of the grace period for the use of MOBILE6, and that another 5 MPOs would have difficulties, but they would be able to use MOBILE6 for their next conformity determination.

We also asked whether the motor vehicle emissions budgets, in the SIP were being updated using MOBILE6. 23 MPOs utilize motor vehicle emissions budgets that were being updated with MOBILE6 and several areas would update the budgets with MOBILE6 once the 8-hour ozone standard is implemented.

Updated: 07/06/2011
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