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Project at a Glance

Title: Monitoring of personal driving habits and vehicle activity

Principal Investigator / Author(s): Arena, Alan

Contractor: Automotive Testing and Development Services

Contract Number: a132-175

Research Program Area: Emissions Monitoring & Control

Topic Areas: Behavioral Change, Mobile Sources & Fuels, Modeling


One important tool used by the California Air Resources Board (CARB) in planning and assessing new motor vehicle regulations is the California motor vehicle emissions inventory model. The emissions factors used to estimate the emissions inventory are obtained from laboratory testing of a subset of the on-road fleet. The vehicle activity data, however, are derived from widely dissimilar databases. An improvement in the motor vehicle emissions inventory can be realized by directly linking the laboratory measured emissions of vehicles to how those same vehicles are driven in the real world.

Seven late model vehicles were each equipped with a datalogging device to monitor their actual on- road usage. These vehicles were selected based on their high sales volume in California and were representative of current and projected future emissions control technologies. The vehicles were loaned to participants of CARB's In-Use Light Duty Vehicle Surveillance Project Series-12 for at least 7 days each. Data from approximately 5000 valid trip files were obtained. A trip database was created from statistical analysis of the collected data with the objective of improving CARB's capability for on-road motor vehicle emission inventory modeling.

Data analysis showed that the average trip was 7.6 miles in length. The average trip lasted 13.6 minutes and 31 % of all trips were one mile or less. About 400/0 of all starts were cold starts and 9% of all soak times were more than I day. The vehicles were driven an average of 49 miles per day and 7.2 trips per day were taken on average. The time spent in cruise, acceleration and deceleration modes varied from participant to participant. Seven significant mode transitions were identified: Idle to Acceleration, Cruise to Acceleration, Cruise to Deceleration, Acceleration to Cruise, Acceleration to Deceleration, Deceleration to Idle, and Deceleration to Cruise were identified. Heavy acceleration represented 1.3% of all vehicle operation and 4.6% of all acceleration modes. Findings in this study deviate from current estimates used in the motor vehicle emissions inventory model.


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

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