Research Projects

Project at a Glance

Project Status: complete

Title: Feasibility and demonstration of network simulation techniques for estimation of emissions in a large urban area.

Principal Investigator / Author(s): Skabardonis, Alex

Contractor: Deakin, Harvey, Skabardonis, Inc,

Contract Number: A132-166

Research Program Area: Emissions Monitoring & Control, Atmospheric Processes

Topic Areas: Mobile Sources & Fuels


Recent requirements for reducing air pollutant emissions set forth by the California and Federal Clean Air Acts require development of improved techniques for estimating emissions from motor vehicles, and assessing the effectiveness of emission control measures. A full understanding of the mobile source emissions burden requires a better representation of the driving modes that produce extraordinary levels of emissions, particularly accelerations, and there is great interest in predicting vehicle activity by mode of operation. The objective of the study described in this report was to develop an integrated modeling framework to produce detailed emission inventories for large urban areas.

Alternative approaches for an integrated model were developed, including ways for directly linking the traditional four-step planning models with microscopic network simulation models, and indirect sampling techniques consisting of relationships between vehicle activity and link characteristics. The alternative approaches were evaluated considering accuracy of predictions, input data and computational requirements, and the state-of-practice in regional modeling. The sampling approach had the highest cost-effectiveness for regional studies, and was selected for implementation.

Relationships were developed between the time spent in each driving mode and basic link characteristics based on simulations of selected real-world surface street networks and freeway sections using the TRAF-NETSIM and INTRAS models, supplemented by field data. These relationships were then incorporated in a specially written computer program as a post-processor to the widely used MINUTP planning model. The integrated model was applied to the entire 1120 zone MTC San Francisco Bay Area network to obtain the time-spent per driving mode. The analysis of the results demonstrated the applicability of the model to predict vehicle activity in regional studies. The report also provides recommendations for improving the modeling techniques for air quality analysis.


For questions regarding research reports, contact: Heather Choi at (916) 322-3893

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