00193364

Component

http://onlinepubs.trb.org...s/trr/1978/670/670-007.pdf

http://scholar.google.com...hock&publication_year=1978

The General Motors sulfate dispersion experiment was conducted in October 1975 at the General Motors Milford Proving Ground. The experiment simulated a four-lane freeway; 352 catalyst-equipped automobiles were driven at 80 km/h, resulting in a traffic volume of 5462 vehicles/h. The runs were conducted in the morning to obtain the most adverse conditions for pollutant dispersion. The maximum catalyst sulfate exposure near the roadway averaged 8 ug/cu m for sixty-six o.5-h runs. The average sulfate emission rate for each vehicle was 0.023 g/km. Near the roadway, mechanical mixing due to the traffic dominated the mixing caused by the ambient turbulence. At low cross-road winds, plume rise becomes important. The U.S. Environmental Protection Agency's HIWAY model was found to overestimate the concentrations at the pedestriat level under stable conditions. These overestimates become worse as the wind speed decreases, as the wind direction approaches parallel to the road, and as the distance from the road increases. A simple line-source model was constructed to remedy many of the limitations low cross-road winds. It also avoids a cumbersome numerical integration required in the HIWAY model. An advection-diffusion model was also constructed in which the eddy diffusivity was determined from dynamic considerations. The influence of traffic was approximated by an additive component in the diffusivity tensor. Good agreements with observations were found, even when the off-diagonal terms of the diffusivity tensor were neglected. It is also expected that when the vehicle velocity is reduced, the extent of pollutant dispersion would also be reduced. /Author/

Sponsored by Committee on Transportation and Air Quality Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.

01411509

pp 36-43

1978

Transportation Research Record

Digital/other

Figures (9) ; Photos (2) ; References (13)

Air pollution; Freeways; Motor vehicles; Pollutants; Simulation; Speed; Sulfates; Traffic speed; Traffic volume; Velocity; Wind

General Motors Co

Environment; Highways; Operations and Traffic Management; Vehicles and Equipment

TRIS, TRB

May 26 1979 12:00AM

• AIR QUALITY CONSIDERATIONS IN TRANSPORTATION PLANNING
• ATMOSPHERIC AND WIND TUNNEL STUDIES OF AIR POLLUTION DISPERSION NEAR HIGHWAYS
• DEVELOPMENT OF A METHOD TO RELATE 8-HOUR TRIP GENERATION TO EMISSIONS CHARACTERISTICS
• EXPERIENCE WITH CONSISTENCY REVIEWS IN FOUR METROPOLITAN AREAS
• INTEGRATED PLANNING AND MANAGEMENT OF TRANSPORTATION AND AIR QUALITY
• INTEGRATING AIR QUALITY CONSIDERATIONS AND THE TRANSPORTATION PLANNING PROCESS: EXPERIENCE IN THE WASHINGTON AREA
• MONITORING AND MODELING OF RESUSPENDED ROADWAY DUST NEAR URBAN ARTERIALS
• OVERVIEW OF THE NEW YORK STATE LONG ISLAND EXPRESSWAY DISPERSION EXPERIMENT
• OXIDANT MODEL APPLICATIONS: DENVER
• OXIDANT MODELING STATUS
• PHOTOCHEMICAL OXIDANTS IN PHOENIX
• REGIONAL AIR QUALITY MODELING IN LOS ANGELES
• REVIEW OF U.S. ENVIRONMENTAL PROTECTION AGENCY GUIDELINES FOR EVALUATING INDIRECT SOURCES AND CARBON MONOXIDE HOT SPOTS
• ROLE OF THE FEDERAL HIGHWAY ADMINISTRATION UNDER THE CLEAN AIR ACT AMENDMENTS OF 1977