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AIR QUALITY TEAM

Project Level Conformity Hot-Spot Analysis (Highways)




Criteria for Evaluating Project
Pollutants
Comments
CO
PM (PM10 and PM2.5)
 
Regulatory Basis
Transportation Conformity Rule
Transportation Conformity Rule
40 CFR 93.116 and 93.123
Applicable Guidance
EPA Guideline for Modeling CO
EPA/FHWA Qualitative PM Hot-spot Guidance
Criteria defining analysis approach
Some level of analysis required for all projects
Analysis only required for projects of air quality concern
Interagency consultation should be used to ensure proper level of analysis
1. Type of projects that require analysis
Projects affecting one or more of the top three intersections with highest traffic volumes and projects affecting one or more of the top three intersections with the worst level of service
New highways with a significant number of diesel vehicles and expanded highway with a significant increase in diesel vehicles
CO: Top intersections defined in SIP
PM: Includes highway improvements that connect to a major freight, bus or intermodal terminal
AADT Volume
Top three highest traffic volumes; top three worst level of service
New highway: Greater than 125, 000 (example)
Expanded highway: Not applicable
PM: Explained in 71 FR 12491
Percent Diesel Traffic
Not applicable
New highway: 8% or more (example)
Expanded highway: Significant increase (not defined)
PM: Explained in 71 FR 12491
Significant increase: Discuss through interagency consultation
2. Type of projects that require analysis
Projects affecting intersections that are at Level-of-Service D, E, or F or that will change to Level-of-Service D, E, or F.
Projects affecting intersections that are at Level-of-Service D, E, or F with a significant number of diesel vehicles or that will change to Level-of-Service D, E, or F.
PM: Focused on intersections with a significant number of diesel vehicles
AADT Volume
Defined by Level-of-Service
Defined by Level-of-Service
Percent Diesel Traffic
Not applicable
Not defined
3. Type of projects that require analysis
Projects in or affecting locations, areas, or categories of sites which are identified in the applicable implementation plan
Projects in or affecting locations, areas, or categories of sites which are identified in the PM10 or PM2.5 applicable implementation plan
AADT Volume
May be defined in SIP
May be defined in SIP
Percent Diesel Traffic
May be defined in SIP
May be defined in SIP
Receptor Sensitivity
At least 3 m from the edge of the travel lane
Not defined
CO: Per EPA’s modeling guidance
Other Considerations
Urban Background Concentration
Discussed in EPA Guidance and FHWA Memo; generally ranges between 2.5 and 5 ppm
Considered through the use of existing monitors in the nonattainment or maintenance area
Discuss through interagency consultation; should reflect local condition
Definition of Project Boundary
The area substantially affected by the project.
The area substantially affected by the project.
Explained in 58 FR 62212
Analysis Methods
Quantitative if meet above requirements, otherwise, analysis may be qualitative
Qualitative, until EPA release modeling guidance in the Federal Register
Analysis Year
Year(s) of peak emissions during the time frame of the transportation plan
Year(s) of peak emissions during the time frame of the transportation plan
Explained in 69 FR 40056
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