The A9-8 tables of the 1993 Handbook provide a
methodology and emission factors for calculating off-road mobile source
emissions from equipment such as loaders, tractors, dozers, graders, etc.
Using this methodology requires relatively detailed knowledge of the types
of equipment that may be used as part of a proposed project. The CEQA
practitioner may use the 1993 Handbook methodology to calculate off-road
mobile source emissions. Alternatively, to simplify calculating off-road
mobile source emissions the CEQA practitioner may use the composite
off-road emission factors from CARB's
Off-Road Model. The composite off road emission factors were derived
based on the equipment category (tractor, dozer, scraper, etc.), average
fleet make-up for each year through 2020, vehicle population (number) in
each equipment category by horsepower rating and load factor. Two types
of composite emission factors have been developed - composite and
horsepower-based composite factors. Composite emission factors have
horsepower rating and load factors already built into the emission
factors, so the CEQA practitioner does not necessarily need to know these
two parameters when calculating off-road mobile source emissions.
Horsepower-based composite factors have load factor ratings built into the
emission factors. The CEQA practitioner can choose the appropriate
equipment by horsepower rating, if this is known, to tailor the analysis
of the proposed project to more accurately estimate emissions.
Daily emissions are calculated as
E = n x H x EF
E = emission in pounds per day
n = number of pieces of equipment in a specified equipment category
H = hours per day of equipment operation
EF = the off-road mobile source emission factor by equipment category or
horsepower-based equipment category in pounds per hour (to access the
composite off-road emission factors, click on the "Off-road Mobile Source
Emission Factors (Scenario Years 2006 – 2020)" hypertext link below)
Please note, the following off-road emission factors include CO2
and CH4 emission factors.