February 24, 2023

Lisa Aultman-Hall, Professor and Chair of Systems Design Engineering at the University of Waterloo


Estimating Aviation vs Passenger Vehicle Greenhouse Gas Emissions for Surveyed Intercity Trips


1:40pm - 3:00pm


1605 Tilia, Room 1103, West Village


Transportation is a large contributor to greenhouse gas emissions (GHG). Within transportation planning the focus of modeling is usually local daily trips within one’s home community.  However, the proportion of passenger distance for long-distance, intercity travel is estimated to be 30% of the total for air, on-road passenger vehicle, rail, and other modes. Methods for estimating and mitigating these emissions have received limited focus in travel modeling to assess the potential reductions possible through modal shift, vehicle occupancy, or long-distance destination choice.

The focus of this research was the design and implementation of a carbon calculator to estimate CO2 emissions for passenger aviation options for surveyed real-world trips. This model facilitated assessment of when it is more efficient to drive or fly in one’s personal context. The calculator increased the accuracy of trip mode-based emissions for long-distance trips by accounting for airport operations, ground side equipment, airport access/egress, and routing which embodies different numbers of take-offs, landings, and taxiing operations. The calculator was applied to 2,112 surveyed one-way trips in the continental US over 250-miles reported by 697 people.  The results showed that the additional variables introduced to the carbon calculator for access and egress travel and airport operations, accounted for about half of the total emissions of an individual trip using air. This demonstrates that the current air travel carbon calculators are missing a significant proportion of emissions from these sources and that non-primary mode travel, airport operations and air routing should be accounted for.

A large portion of the variability evident in the model output was attributable to actual variation in the aviation system and services: routing, plane type, and airplane passenger load.  These are elements outside the control of the traveler and point to the need for system-wide analysis and modeling to address balance of modes between air and ground for intercity trips.

Biographical Sketch

Dr. Lisa Aultman-Hall is Professor and Chair of Systems Design Engineering at the University of Waterloo in Ontario Canada.  Dr. Aultman-Hall focuses on transportation systems, especially methods to collect unique databases for modeling and analysis of long-distance travel, transportation sector emissions, network resiliency, streetscape design, and non-motorized transportation.  Until recently, as Professor of Civil Engineering, she served several leadership roles at the interdisciplinary University of Vermont Transportation Research Center.  This included serving as Associate Director of the National Center for Sustainable Transportation led by UC Davis ITS.  In this role, Dr. Aultman-Hall enjoyed 8 semesters as a visiting scholar at Davis ITS over the last decade. 

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