Implications of using MVEI 7f and MVEI 7g for carbon monoxide (CO) conformity determination
- Univ. of California, Davis, CA (United States)
The California Air Resources Board (CARB) develops updated versions of their motor vehicle emissions inventory (MVEI) models to more accurately predict impacts on air quality due to motor vehicle emissions. Output from EMFAC is used by the California Department of Transportation (CALTRANS) in conjunction with DTIM or BURDEN to calculate microscale emissions inventories and determine whether proposed transportation plans meet the conformity requirement or exceed a particular county`s emissions budget. The recent changes made to CARB`s MVEI programs in moving from EMFAC 7f to EMFAC 7g have significant impacts on modeled emissions of air pollutants. An analysis of the impacts of those changes is presented. The changes having the greatest impact on modeled carbon monoxide (CO) emissions are the following: (1) EMFAC 7g continuous start methodology, (2) EMFAC 7g cycle correction factor (CCF), and (3) EMFAC 7g high emitter correction factor (HECF). With respect to CO emissions, the vehicle class most affected by the changes from MVEI 7f to MVEI 7g, is light-duty autos (LDAs). Implications of using MVEI 7g on the microscale level include the following: (1) regional emissions predicted by MVEI 7g are much higher than those predicted by MVEI 7f, (2) California county budgets were set with MVEI 7f and conformity will be difficult to achieve using MVEI 7g, (3) the new definition of a 100s start decreases modeled CO emissions, (4) CCFs significantly increase modeled CO emissions, (5) CCFs are regional correction factors, intended to represent emissions in the South Coast Air Basin (SCAB) not captured by the Federal Test Procedure (FTP) drive cycle, and may or may not be applicable on a given link, (6) BURDEN 7g or DTIM may incorrectly predict CO emissions when used on the microscale level because CCFs are applied in EMFAC, and (7) HECFs significantly increase modeled CO emissions.
- OSTI ID:
- 351695
- Report Number(s):
- CONF-970677--
- Country of Publication:
- United States
- Language:
- English
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