Paper Details

TRB 90th Annual Meeting (January 23-27, 2011)

Event Number:	479
Event Title:	Current Environmental Issues in Transportation
Event Date:	Jan 25 2011 9:30AM- 12:00PM
Event Location:	Hilton, International Center
Event Description:
Event Agenda:

Motorists’ Exposure to Traffic-Related Air Pollution: Modeling the Effects of Traffic Characteristics (11-2931)

This paper proposes a road-user exposure model that is a function of fundamental traffic characteristics. The model is then applied to a 14-mile congested corridor in Portland, Oregon using real-world traffic data. The modeling results show a wide range of exposures through the corridor over the course of a day and suggest that traffic congestion increases motorists’ exposure to traffic-related pollution. Large peak-period trip exposures are primarily the result of increased exposure durations due to longer travel times. Roadway exposure concentrations (and temporal inhalation rates) also increase during peak periods due to heavy traffic flows and increased marginal emissions rates (though the direct effects of traffic speed on exposure concentrations were small for the case studied). Traffic-induced dispersion increases with higher flows – slightly offsetting the increased roadway emissions during heavy traffic flow. It should be noted that while travel time is the dominant factor in high peak-period exposure, long travel times are driven by traffic characteristics. From a roadway perspective, these results suggest that exposure mitigation should focus on reducing the time spent in the roadway and reducing the volume flow of vehicles on the roadway – while recognizing that these are intertwined travel behaviors. In particular, traveler delay time is less deleterious when spent on low-flow sections than high-flow sections. Finally, individual travelers can greatly reduce their roadway exposure by adjusting their departure time to less congested, lower volume periods.

Authors
     Bigazzi, Alexander York, Portland State University
     Figliozzi, Miguel , Portland State University
     Clifton, Kelly J., Portland State University