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Modeling Airport Ground Transportation Emissions. Geoffrey D. Gosling National Center of Excellence for Aviation Operations Research University of California at Berkeley Presentation to the Airport Air Quality Symposium San Diego, California, March 1-2, 2001. Presentation Outline.
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ModelingAirport Ground Transportation Emissions Geoffrey D. Gosling National Center of Excellence for Aviation Operations Research University of California at Berkeley Presentation to the Airport Air Quality Symposium San Diego, California, March 1-2, 2001
Presentation Outline • Role of ground transportation in overall airport related emissions • Existing models and analysis techniques • Issues in modeling ground access vehicle emissions • Assessing the impacts of proposed mitigation measures • Modeling changes in ground access mode use
Ground Transportation Share of Total EmissionsLAX Unmitigated No Action/No Project (tons/year)
Role of Ground Transportation in Overall Airport Related Emissions • Share of total emissions expected to decline over time • Emission levels responsive to airport policies and programs • Aircraft emissions outside airport control • Local concentrations of pollutants • Curbfront areas; access roadway intersections • Potential for emission reduction credits
Existing Models and Analysis Techniques • Emissions and Dispersion Modeling System • Component models • Mobile5a • CALINE3 • General purpose transportation models • EMFAC, PART5, CAL3QHCR • Aggregate analysis • Ratios of emissions to VMT • California ARB cost-effectiveness analysis methods
Emissions and Dispersion Modeling System • Designed to model on-airport facilities • Roadway and curbfront segments • Segment location • User inputs traffic volume • Parking lot and similar facilities • Location, size and shape (rectangular components) • User inputs vehicle trips and average trip length • Vehicle fleet composition • Assumes a “typical” mix of vehicle types
Issues in ModelingGround Access Vehicle Emissions • Extent of trip to consider • On-airport vs. origin-destination • Effect of trip characteristics on hot soaks and cold starts • Drop-off/pick-up vs. park for duration of air trip • Effect of roadway and curbfront congestion • Impact of mitigation measures on fleet composition and trip characteristics
Assessing the Impacts ofProposed Mitigation Measures • Range of mitigation measures to consider • Nature of impact on emissions • Use of vehicles producing less emissions • Change in access/egress travel patterns • Need to predict behavioral response • Airport users • Ground transportation service providers • Cost-effectiveness considerations
Range of Potential Mitigation Measures • Convert vehicle fleets to alternative fuels • Shuttle buses, shared-ride vans, taxis, rental cars • Implement employee trip reduction programs • Improve links to transit facilities • Traffic engineering / management measures on adjacent roadways • Develop off-airport terminals (park-and-ride) • Airport access tolls; raise parking rates
Modeling Changes in Ground Access Mode Use • Choice of access mode and service providers determines effect of mitigation measures • Vehicle trips and traffic composition • Roadway segments and facilities used • Complex choice process • Multiple modes and services • Choices influenced by trip characteristics • User costs influence choice process and cost of implementing mitigation measures
Multinomial Logit Choice Model where Typical utility structure: U j = a0 + a1{travel time} + a2{wait time} + a3{cost}
Nested Logit Mode Choice Structure Auto Door-to-Door Scheduled Bus Public Transit Rental Car Shared-Ride Van Off-Airport Terminal Drop-off Taxi Access Park Limousine Drop-off Park Lot Taxi Short-Term Transit Long-Term Airport Bus Off-Airport Stop
Implementation Considerations • Absence of industry-standard models • Several regions have developed their own models • Models need to be configured and calibrated for each application • Very data intensive • Airport ground transportation services • Regional transportation system • Broad application to airport ground transportation planning
Conclusions • Procedures and models for estimating emissions and dispersion for a given traffic volume and characteristics well defined • Assessment of the likely effect of proposed mitigation measures not so well defined • Need ability to predict user response to changes • Emission reduction assumptions need to be based on behavioral choice modeling