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Title: Characterization of the off-road equipment population

Principal Investigator / Author(s): Baker, Rick

Contractor: Eastern Research Group

Contract Number: 04-315

Research Program Area: Emissions Monitoring & Control

Topic Areas: Agriculture, Mobile Sources & Fuels


Off-road equipment is a major contributor to pollution levels in California, generating ozone precursors, particulate matter, toxics, and carbon dioxide. These equipment are found in a wide variety of applications, including lawnmowers, bulldozers, aircraft support equipment, and portable generators, among other categories. Off-road equipment is used in essentially all types of businesses, as well as in residential applications. Given the large number of engines involved, and the highly diverse set of operators, off-road engines have proven more difficult to characterize and control than many other emission categories.

In order to develop a more comprehensive and consistent data set of engine characteristics and activity, ARB contracted with Eastern Research Group (ERG) to conduct a study of off-road engines less than 175 horsepower operating in the state. The study was conducted in two phases, with equipment operator surveys and equipment instrumentation techniques developed and tested under Phase I, and full scale data collection and analysis taking place under Phase II. The study results include detailed information on equipment characteristics and activity, including application type, horsepower, and hours per year of use. Surrogates were developed to extrapolate the survey data to statewide totals, as well as to allocate equipment populations to the county level. Instrumentation of data loggers was also performed to collect engine-on time, in-use RPM and exhaust gas temperature data for different types of construction equipment. Based on the study findings, recommendations are provided for updating the current OFFROAD emission factor model, as well as the list of federally preempted off-road equipment in California.


For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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