Final Section 9

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**SECTION 9 CONFORMITY**  **9.1 Purpose of Section**  This section establishes Transportation Conformity budgets for the on

- road mobile source sector for EMA and WMA in the 2008 RFP milestone y ear and in the 2009 attainment demonstration ye ar. The Transportatio n Conformity budgets set the levels of mobile source emissions that may not be exceeded in the each area in the budget ye ars. The budgets were developed using methods agreed upon b y staff of the Massachusetts Executive Office of Transportation and Public W orks, Office of Transportation and Planning (EOT), MassDEP, and EPA Region 1 through the conformity

consultation process. Technical data files related to the Mobile 6 model runs used to estimate mobile source emissions in the budget y ears are in the Append ix 9. **9.2 Background**  Transportation conformity is required b y section 176(c) of the CAA to ensure that transportation plans, programs and projects receiving federal funds are consistent with the SI P . Conformity to a SI P means that transportation activ ities will not produce new air quality violations, worsen existing violations, or delay timel y attainment of a NAAQS. EPA’s Phase 2 Implementation Rule provides that nonattainment areas establish motor vehicle emissions budgets for the RFP milestone y ear (2008) and for the attainment demonstration y ear (2009). The budgets are set at the level of emissions from the on

- road mobile sector projected for these y ears. Emissions of VOC and NOx from this sector may not exceed the budget levels. Emissions in year s for which no budget is set may not exceed the budget established for the most recent prior year. MassDEP established conformity budgets for EMA and WMA under the 1

- hour ozone standard. For WMA, MassDEP submitted to EPA a 1

- hour ozone standard attainmen t demonstration in 1998, which established budgets for the 2003 attainment y ear. EPA found the WMA budgets adequate for conformity

purposes on February

9, 1999. For EMA, MassDEP submitted to EPA a 1

- hour ozone standard attainment demonstration in Septembe r 2002, which established budgets for the 2007 attainment year. EPA found the EMA budget adequate for conformity purposes on December 6, 2002. (The 2003 WMA and 2007 EMA budgets are shown in Table 9.1) These 2008 and 2009 transportation conformity budg ets, once deemed adequate by EPA, will replace the conformity

budgets previously

submitted and approved. **9.3 Methodology**  Conformity

budgets are set through a conformity consultation process. The 2008 and 2009 budgets for EMA and WMA were developed us ing methods agreed upon by staff from the Office of Transportation Planning (EOT), MassDEP, and EPA Region 1 pursuant to the consultation process. EOT has summarized these methods as follows:Final Section 9

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• The latest version of the Massachusetts Statewide Travel Dem and model 1 was the primary source used to estimate travel speeds and vehicle miles of travel (VMT), based on the latest planning assumptions, socio

- economic data, and professional judgment about travel characteristics and growth. The statewide model was us ed for all areas in Massachusetts except for the Boston and Berkshire Metropolitan Planning Organization (MPO) areas (where regional models were used to be full y consistent with the latest planning assumptions). • The travel demand model reflects the highway network and has a “base year” of 2000, which has been initially

“calibrated” to replicate traffic patterns from that y ear, based on various information, including recorded traffic counts and 2000 U.S. Census data. • A 2008 RFP y ear and 2009 attainme nt y ear model were developed from the base y ear model, which contains the latest planning assumptions regarding growth projections, including socio

- economic changes and updating the roadway network in the model to incorporate regionally

significant highway projects reasonably expected to be completed by 2008 and b y 2009. • Emission rates (usually

in grams of pollutant per mile at given travel speeds) are applied to VMT and speed results from the model to estimate total vehicle emissions. The emission rate s were provided by

DEP and are based on EPA’s MOBILE 6.2 model. These rates

– developed specificall y for the years 2008 and 2009

– are based on a variety of assumptions about vehicle fleet mix and technology , fuel composition, and pollution control programs. Two sets of rates were used: One set for expressway travel and another for non

- expressway travel. (Emission rates are in Appendix 9A.) • Estimates of emissions from the model are factored to VMT data from the Highway Performance Monitoring Sy stem (HPM S), as federal regulations require HPMS VMT to be the primary

measure of VMT within a nonattainment area. These "HPMS factors" are calculated from the results of the base ye ar model; the factors are equal to the ratio of 2000 HPMS VMT to 2000 modeled VMT, and vary by MPO region. (See Appendix 9 B) • A seasonal adjustment factor is also applied to the statewide travel demand model and regional model results to replicate summertime conditions (when ozone concentrations are typicall y highest). Most travel mo dels represent spring or fall conditions, where certain input data (employ ment, schools) are more representative of y ear - round figures. The seasonal adjustment factor represents the ratio of summer traffic levels to annual average traffic. • Model VMT an d speed output were separated b y region, and further split into expressway vs. non - expressway

results. Then the appropriate emission rates were applied to produce the rough emission totals. These totals were then factored to HPMS data, and finally seasonal ly adjusted to produce the modeled emission totals.

1 While the Statewide Travel Demand Model is often updated, there are no specific dates or version numbers attached to the updates. The version used for the 2008 and 2009 conf ormity budgets was the latest update as of 10/17/07.Final Section 9

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• In EMA, net emission estimates from commuter rail, bus, and boat services are included in the totals, with most accounted for in the results for the Boston MPO region. The remaining "off

model" estimates

– covering several regions and categorized as “Other Eastern Massachusetts”

– were calculated by the Central Transportation Planning Staff (CTPS) of the Boston MPO, and include: 1) Additional net commuter rail emissions generated outside the Boston MPO region, and 2) Emission estimates of daily VMT savings realized from carpooling at various park and ride lots located in several regions. The off

- model estimates were added to the modeled emission totals to produce the final 2008 mobile source emission es timate totals used for the RFP budget development. (The “off

- road” estimates are described in Appendix 9 C.)

• Calibration of a travel demand model is often a continuing process in order to achieve results that are more accurate and to keep pace with chan ges in the latest planning assumptions and growth projections. As in the past with other model sets, future model output and HPMS adjustment factors can change as the statewide model and regional models are made more accurate and updated assumptions are in corporated. **9.4 Mobile Source Budgets**  Application of the methods described above results in projected emissions for the 2008 and 2009 ye ars for the EMA and WMA attainment y ears as shown in Table 9.1. These emissions represent the 8

- hour ozone standard budgets for EMA and WMA. 2
**Table TC 1 2008 and 2009 EMA and WMA Mobile Source Budgets** Tons per summer day **2008 2008**  **2009 2009**  **VOC NOx**  **VOC NOx**  **Eastern MA** 68.30 191.30 63.50 174.96 **Western MA** 11.80 31.30 10.73 27.73 Prior 1
- hour budge ts 2007 2007 EMA 86.70 226.36 WM A 2003 2003 23.77 49.11

2 Emissions estimated by Metropolitan Planning Organization Region are in Appendix 9 D.