The qualitative hot spot analysis for the Corridor X / I-65 project indicates:
VISTAS and ASIP modeling indicates that the Clean Air Interstate Rule along with national mobile source controls will result in about a 1ug/m3 reduction in the background concentration in the Birmingham area by 2010. The Jefferson County Department of Health and ADEM are also developing a State Implementation Plan to bring the area into attainment beginning in 2010, prior to the open-to-traffic date of 2012.
The emissions from the on-road mobile sources will decline and are projected to remain below 2002 base year levels through 2030, which is the last year of the current transportation plan. The newest regulations requiring Ultra Low Sulfur Diesel (ULSD) fuel began in 2007. The effect of ULSD is realized only through the use of new technology diesel engines that when operated with ULSD produce 90% less PM emissions than current diesel engines. Information from industry sources indicates that new vehicles comprise approximately 6% of the fleet vehicles each year11. By opening year of this project the makeup of the diesel fleet utilizing new technology engines will be approximately 30% of the fleet.
By the year 2010 all highway diesel fuel must be ULSD. Owners of 2007 and later model year diesel-powered highway vehicles must refuel only with ULSD fuel. Owners of 2006 and earlier model year diesel-powered highway engines and vehicles may use ULSD or Low Sulfur Diesel fuel during the transition period. Only ULSD fuel will be available for highway use starting on December 1, 2010. This date is two years prior to the opening of the project.
The "Particulate Matter Sources in Birmingham, Alabama" study indicates that a larger region, including more rural portions of Jefferson County, have annual-average PM2.5 concentrations of 12 to 14 ug/m3, approaching the ambient air quality standard of 15 ug/m3. Superimposed on these high regional levels is an urban concentration increment of approximately 2 ug/m3. In the case of NBHM, an additional highly localized increment of 3 to 4 ug/m3 is also present. It is observed that at the Hoover and Leeds sites with comparable traffic volumes and truck percentages there were no violations through 2004, providing support for the observation that the problems at the NBHM and Wylam monitors are principally from local sources other than on road motor vehicles.
It is observed that the Hoover and Leeds monitors have not been in violation of the PM2.5 standards through the period represented by the "Particulate Matter Sources in Birmingham, Alabama" study. The Hoover site has higher traffic numbers than either North Birmingham or the Wylam monitor but does not have the local industrial contributions of the other two sites. The Leeds site also lies in a similar valley situation as the North Birmingham monitors and has a higher percentage of truck traffic than either of the exceeding monitors. The common thread appears to be the presence or lack thereof of the industrial contributions to local air quality.
Although the travel demand models and historical growth patterns show an increase in traffic volumes and VMT, current regional conformity modeling demonstrates that vehicular emission contribution to PM2.5 will remain below the 2002 levels through 2030, which is the last year of the current transportation plan. Emissions are expected to be reduced in the project area as demonstrated by projected reductions in the regional emissions as compared to 2002 and 2009 levels, as well as by national projections by the EPA reflecting the impacts of national emission control programs, such as the 2007 Heavy-Duty Diesel Rule.
Regional travel demand modeling demonstrates that on-road emissions of PM2.5 drop by 29% through 2009 and drop an additional 13% by 2015 for a total reduction of 42% through 2015. The improvements to the transportation network as demonstrated in the select link analysis will significantly improve the operational characteristics of the network and LOS in the project area will improve from LOC F to LOS C, moving traffic into and through the area more efficiently.
Based on the qualitative analysis, it is determined that the Corridor X and I-65 project meet all of the project-level conformity requirements, and that the improvements associated with the project will not will not cause or contribute to a new violation of the PM2.5 NAAQS or increase the frequency or severity of a violation. This qualitative evaluation points to a pattern linking PM mass concentrations more closely with local industrial sources than with transportation sources. The improvements in engine technology, the lowering of sulfur content in the diesel fuel, the improved operational efficiency of the transportation network, and the turnover in the vehicle fleet will offset the increase in traffic associated with the project and support the conclusion that the project will not will not cause or contribute to a new violation of the PM2.5 NAAQS, or increase the frequency or severity of a violation.