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Project Status: complete

Report Published July 1985:

Title: Assessment of heavy-duty gasoline and diesel vehicles in California: population and use patterns.

Principal Investigator / Author(s): Yuji Horie

Contractor: Pacific Environmental Services, Inc.

Contract Number: A2-155-32

Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels


As emissions from light-duty vehicles come under more stringent control, heavy-duty vehicles (HDVS) will account for an ever larger share of total mobile source emissions. Accordingly, the Air Resources Board (ARB) wants improved estimates of air pollutant emissions, especially emissions of oxides of nitrogen and particulates, from HDVs.

To achieve that goal, ARB needs an improved methodology for estimating vehicle miles traveled (VMT) by HDVs in each of the 58 counties and 14 air basins in California. Therefore, in this study, Pacific Environmental Services, Inc. (PES) has developed a new estimation method, based on CALTRANS VMT data and other supplementary data, and has estimated truck VMT for various subregions of the state and for HDV subcategories.

The new methodology utilizes VMT data generated by two CALTRANS annual studies: Truck Program and Highway Performance Monitoring System (HPMS). To fill the gaps between the types of information extractable from the CALTRANS data and those needed by ARB, several types of auxiliary data have been acquired through literature search and two special surveys: a special truck traffic survey on 21 different routes selected from city and county roads; and a telephone questionnaire survey on vehicle usage of 622 randomly selected HDVs. Also, out-of-state truck activities in California have been estimated by analyzing data from the 1976 Interstate Commerce Commission Survey and the 1971 Institute of Transportation and Traffic Engineering Survey.

The CALTRANS data bases and the auxiliary data were merged in a computer program named "HDV", especially developed by PES, to compute truck VMT for many geographical subregions and for HDV subcategories. The results are presented in a tabular form in the report.


For questions regarding this research project, including available data and progress status, contact: Heather Choi at (916) 322-3893

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