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Table A9-5 of the 1993 Handbook
provides a methodology for calculating on-road mobile source emissions
using EMFAC output files based on the year of interest, typical average
speeds, etc. When using this methodology, the most current version of
EMFAC should be used – DO NOT USE TABLES A9-5-J-1 THROUGH A9-5-J-10 OR
TABLES A9-5-K-1 THROUGH A9-5-K-10. This methodology requires relatively
detailed information about a project to be able to calculate on-road
mobile source emissions. To simplify calculating on-road mobile source
emissions, the SCAQMD has derived mobile source emission factors using
CARB’s EMFAC 2007 (v2.3) BURDEN model. The emission factors are derived
by dividing the total daily district-wide emissions by total daily vehicle
miles traveled to obtain emission factors in pounds per mile traveled. To
assist the CEQA practitioner, two sets of emission factors have been
developed as described below.
Please note, the on-road emission factors below include CO2 and
CH4 emission factors.
The following emission factors
have been derived by taking the weighted average of vehicle types and
simplifying them into two categories – passenger/light-duty and
medium-/heavy-duty vehicles (e.g., delivery trucks). These emission
factors should be used for typical land use projects where
passenger/light-duty vehicles generate the majority of the vehicle trips.
Heavy-Heavy-Duty Vehicles
The following emission factors
have been derived specifically for the heavy-heavy-duty truck (HHDT)
vehicle category. HHDTs have a vehicle weight ranging between 33,001 to
60,000 pounds. These emission factors should be used to calculate on-road
mobile source emissions for projects where HHDTs comprise a relatively
large percentage of the total vehicle trips from a project (approximately
10 percent of more). These emission factors should be used for projects
that generate a large number of HHDT trips per day, such as
warehouse/distribution facilities, landfills, etc. Since these types of
projects may also include passenger/light-duty vehicles, the emission
factors above should be used to calculate mobile source emissions for the
passenger/light-duty vehicles in conjunction with the following emission
factors to calculate total on-road mobile source emissions for a project.
The following HHDT factors (or the appropriate EMFAC 2007 emission
factors) should also be used when performing a mobile source toxics
analysis (see below).
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