The National Academies

ACRP 02-63 [Final]

Quantifying Airport Ground Access Vehicle Activity for Emissions Modeling

  Project Data
Funds: $299,874
Research Agency: KB Environmental Sciences
Principal Investigator: Michael Kenney
Effective Date: 6/1/2015
Completion Date: 4/28/2017

Airports conduct air quality assessments for various reasons, including inventories, conformity determination, NEPA studies, and health studies. Ground access vehicles (any vehicle licensed to operate on public roads and hereafter noted as “GAV”) may be a significant contributor to airport emissions. Yet there is no guidance for quantifying airport GAV activity for the purposes of emissions modeling. In many cases, vehicle counts are obtained from airport surveillance systems, toll booth records, traffic mechanisms, etc. In other cases, surveys count vehicles on airport roads and approximate speeds using speed guns, timers, and/or car-chasing. In addition, it is not clear how refined the simulated roadway network should be for an airport air quality assessment study. Depending on the type of study, roadways can be modeled just up to the airport property boundaries or further out. This is important since ground access vehicle emissions may exceed aircraft emissions at some airports. In addition, for those cases when GAV counts and speeds are surveyed, they must be scaled to represent the project year. This forecasting (as well as back-casting, depending on the study requirements) needs to be consistent to ensure airports can measure their progress on emissions reduction initiatives. Research is needed to provide guidance for consistently and accurately quantifying GAV activity for emissions modeling.
The objective of this research is to develop a guidebook of evidence-based best practices to help airport industry practitioners quantify GAV activity for emissions modeling. The guidebook should address, at a minimum, the following:
  • Definition and description of GAV and vehicle activity types (e.g., private vehicle and taxi pickup/drop off, commercial deliveries, airport operations and maintenance);
  • Establishing geographic boundaries based on the type of study (e.g., inventory, conformity, NEPA, health study, greenhouse gas reporting);
  • Inventorying GAV infrastructure (e.g., roadways, parking lots) including characteristics (e.g., number of lanes, speed) for modeling purposes;
  • Determining GAV activities to be included based on study objectives;
  • Determining GAV activity data requirements (e.g., spatial and temporal considerations) for emissions studies based on study objectives;
  • Evaluating available sources of GAV activity data (e.g., traffic studies);
  • Descriptions of methods to collect and estimate GAV activity data to address gaps (e.g., traffic counts, trip generation), including forecasting and back-casting; and
  • A process and/or tool (e.g., matrix, decision tree, flow chart) to help practitioners select the most appropriate approach for matching GAV activity data sources and data-gathering methods with study objectives and resource limitations.


Research is complete.  Results published in ACRP Research Report 180.

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