Roadway air dispersion is applied to highway segments

Roadway air dispersion modeling is the study of air pollutant transport from a roadway or other linear emitter. Computer models are required to conduct this analysis, because of the complex variables involved, including vehicle emissions, vehicle speed, meteorology, and terrain geometry. Line source dispersion has been studied since at least the 1960s, when the regulatory framework in the United States began requiring quantitative analysis of the air pollution consequences of major roadway and airport projects. By the early 1970s this subset of atmospheric dispersion models were being applied to real world cases of highway planning, even including some controversial court cases. Image File history File linksMetadata Download high resolution version (2432x1208, 298 KB) Summary i took this picture in mar 2006 and release all rights Licensing I, the creator of this work, hereby release it into the public domain. ... Image File history File linksMetadata Download high resolution version (2432x1208, 298 KB) Summary i took this picture in mar 2006 and release all rights Licensing I, the creator of this work, hereby release it into the public domain. ... This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ... A computer simulation or a computer model is a computer program which attempts to simulate an abstract model of a particular system. ... Vehicles are non-living means of transportation. ... The word emission generally means sending something out. ... Satellite image of Hurricane Hugo with a polar low visible at the top of the image. ... This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ... This page is related to transport; you may be looking for the 2002 Bollywood movie Road. ... Atmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. ... Highway in Pennsylvania, USA For other uses, see Highway (disambiguation). ...

How the model works

The basic concept of the roadway air dispersion model is to calculate air pollutant levels in the vicinity of highways and arterial roadways. The model takes into account source characteristics such as traffic volume, vehicle speeds, truck mix, and fleet emission controls; in addition, the roadway geometry, surrounding terrain and local meteorology are addressed. For example, many air quality standards require that certain near worst case meteorological conditions be applied. This page is related to transport; you may be looking for the 2002 Bollywood movie Road. ... This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ... Highway in Pennsylvania, USA For other uses, see Highway (disambiguation). ... Section of an artery An artery or arterial is also a class of highway. ... Interstate 80, a freeway in California with many lanes and heavy traffic. ... Vehicles are non-living means of transportation. ... The driver of this DAF tractor with an auto-transport semi-trailer prepares to offload Skoda Octavia cars in Cardiff, Wales For other meanings, see Truck (disambiguation). ... The word emission generally means sending something out. ... Satellite image of Hurricane Hugo with a polar low visible at the top of the image. ... The Air Quality Index (AQI) is a standardized index of the air quality in a given location, given in parts per billion. ...

The calculations are sufficiently complex that a computer model is essential to arrive at authoritative results, although workbook type manuals have been developed as screening techniques. In some cases where results must be refereed (such as legal cases), there may be updated validation of the model using field test data in the local setting; this step is not usually warranted, because the best models have been extensively validated over a wide spectrum of input data variables. A computer simulation or a computer model is a computer program which attempts to simulate an abstract model of a particular system. ...

The product of the calculations is usually a set of isopleths (air pollution contour maps), either in plan view or cross sectional view. Typically these might be stated as concentrations of carbon monoxide, total reactive hydrocarbons, oxides of nitrogen, particulate or benzene. The air quality scientist can run the model successively to study techniques of reducing adverse air pollutant concentrations (for example, by redesigning roadway geometry, altering speed controls or limiting certain types of trucks). The model is frequently utilized in an Environmental Impact Statement involving a major new roadway or land use change which will induce new vehicular traffic. Contour map A contour line (also isopleth, level set, isogram or isarithm) for a function of two variables is a curve connecting points where the function has a particular value. ... This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ... Example of a topographic map with contour lines Topographic maps, also called contour maps, topo maps or topo quads (for quadrangles), are maps that show topography, or land contours, by means of contour lines. ... Archaeological plan In an archaeological excavation, a plan is a drawn record of features (and artefacts) in the horizontal plane. ... Cross section may refer to the following In geometry, Cross section is the intersection of a 3-dimensional body with a plane. ... Carbon monoxide, chemical formula CO, is a colorless, odorless, tasteless, flammable and highly toxic gas. ... In chemistry, a hydrocarbon is a cleaning solution consisting only of carbon (C) and hydrogen (H). ... The term nitrogen oxide is imprecise and can be used to refer to any of these oxides (oxygen compounds) of nitrogen, or to a mixture of them: Nitric oxide (NO), nitrogen(II) oxide Nitrogen dioxide (NO2) Dinitrogen monoxide (N2O) (Nitrous oxide) Dinitrogen trioxide (N2O3) Dinitrogen tetroxide (N2O4) Dinitrogen pentoxide (N2O5... http://visibleearth. ... Benzene, also known as C6H6, PhH, and benzol, is an organic chemical compound that is a colorless and flammable liquid with a pleasant, sweet smell. ... According to the National Environmental Policy Act (NEPA) whenever the U.S. Federal Government takes a major Federal action significantly affecting the quality of the human environment it must first consider the environmental impact in a document called an Environmental Impact Statement (EIS). ...

History

The logical building block for this theory was the use of the Gaussian air pollutant dispersion equation for point sources^[1]. One of the early point source air pollutant plume dispersion equations was derived by Bosanquet and Pearson^[2] in 1936. Their equation did not include the effect of ground reflection of the pollutant plume. Sir Graham Sutton derived a point source air pollutant plume dispersion equation in 1947^[3] which included the assumption of Gaussian distribution for the vertical and crosswind dispersion of the plume and also addressed the effect of ground reflection of the plume. Further advances were made by G. A. Briggs^[4] in model refinement and validation and by D.B. Turner^[5] for his user-friendly workbook that included screening calculations which do not require a computer. Generally, the word gaussian pertains to Carl Friedrich Gauss and his ideas. ... This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ... This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ...

In seeing the need to develop a line source model to approach the study of roadway air pollution, Michael Hogan and Richard Venti developed a closed form solution to integrating the point source equation in a series of publications^[6][7].

The source of virtually all roadway air pollution emissions is the exhaust

While the ESL mathematical model was completed for a line source by 1970, model refinement resulted in what they called a “strip source”, emulating the horizontal extent of the roadway surface. This theory would be the precursor of area source dispersion models. But their intent target was roadway simulation, so they proceeded rapidly with the development of a computer model by adding to the team Leda Patmore, a computer programmer in the field of atmospheric physics and satellite trajectory calculations. A working computer model was produced by late 1970; then the model was calibrated with carbon monoxide field measurements targeting from traffic on U.S. Route 101 in Sunnyvale, California. Image File history File linksMetadata Download high resolution version (2456x1808, 469 KB) Summary i took this photo and release all rights Licensing I, the creator of this work, hereby release it into the public domain. ... Image File history File linksMetadata Download high resolution version (2456x1808, 469 KB) Summary i took this photo and release all rights Licensing I, the creator of this work, hereby release it into the public domain. ... A mathematical model is an abstract model that uses mathematical language to describe the behaviour of a system. ... A computer simulation or a computer model is a computer program which attempts to simulate an abstract model of a particular system. ... U.S. Highway 101, or U.S. Route 101 (U.S. 101), is a north-south highway that is aligned along the Pacific West Coast of the United States. ... Nickname: Motto: Official website: http://www. ...

The ESL model received endorsement from the U.S. Environmental Protection Agency (EPA) in the form of a major grant to validate the model using actual roadway tests of tracer gas sulfur hexaflouride dispersion. That gas was chosen since it does not occur naturally or in vehicular emissions and provides a unique tracer for such dispersion studies. Part of the Environmental Protection Agency’s motives may have been to bring the model into public domain. After a successful validation through the EPA research, the model was soon put to use in a variety of settings to forecast air pollution levels in the vicinity of roadways. The ESL group applied the model to the U.S. Route 101 bypass project in Cloverdale, California, the extension of Interstate 66 through Arlington, Virginia, the widening of the New Jersey Turnpike through Raritan and East Brunswick, New Jersey, and several transportation projects in Boston for the Boston Transportation Planning Review. EPA redirects here. ... EPA redirects here. ... The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ... EPA redirects here. ... U.S. Highway 101, or U.S. Route 101 (U.S. 101), is a north-south highway that is aligned along the Pacific West Coast of the United States. ... Cloverdale is a city located in Sonoma County, California. ... Interstate 66 is an interstate highway in the eastern United States. ... Arlington County is a county located in the U.S. state of Virginia (which calls itself a commonwealth), directly across the Potomac River from Washington, DC. By an act of Congress July 9, 1846, the area south of the Potomac was returned to Virginia effective in 1847 As of 2000... The New Jersey Turnpike is a toll road in New Jersey and is one of the most heavily traveled highways in the United States. ... The Raritan people were a tribe of Lenape Indians who inhabited the areas around the present Raritan Bay in northern New Jersey and Staten Island, New York. ... East Brunswick is an suburban township located in Middlesex County, New Jersey. ... Boston is a town and small port c. ...

By the early 1970s at least two other research groups were known to be actively developing some type to roadway air dispersion model: the Environmental Research and Technology group of Lexington, Massachusetts and CalTrans headquarters in Sacramento, California. The Caline model of Caltrans borrowed some of the technology from the ESL Inc. group, since CalTrans funded some of the early model application work in Cloverdale and other locations and was given rights to use parts of their model. Minute Man statue on Lexington Green, by H. H. Kitson. ... Caltrans logo The soaring ramps in the stack interchanges favored by Caltrans often provide stunning views. ... Nickname: City of Trees Official website: http://www. ... Cloverdale can refer to: Cloverdale, California Cloverdale, Indiana Cloverdale, Ohio Cloverdale, Oregon Cloverdale, Virginia Cloverdale, Western Australia This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

The theory

The resulting solution for an infinite line source is:

where x is the distance from the observer to the roadway, y is the height of the observer, u is the mean wind speed, α is the angle of tilt of the line source relative to the reference frame, and c and d are the standard deviation of horizontal and vertical wind directions (measured in radians) respectively. This equation was integrated into a closed form solution using the error function (erf), and variations in geometry can be performed to include the full infinite line, line segment, elevated line, or arc made from segments. In any case one can calculate three dimensional contours of resulting air pollutant concentrations and use the mathematical model to study alternative roadway designs, various assumptions of worst case meteorology or varying traffic conditons (for example, variations in truck mix, fleet emission controls, or vehicle speed. A mathematical model is an abstract model that uses mathematical language to describe the behaviour of a system. ...

The ESL research group also extended their model by introducing the area source concept of a vertical strip to simulate the mixing zone on the highway produced by vehicle turbulence. This model too was validated in 1971 and showed good correlation with field test data. In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic, stochastic property changes. ...

Example applications of the model

Roadway air dispersion modeling is also done for curved roadways

There were several early applications of the model in somewhat dramatic cases. In 1971 the Arlington Coalition on Transportation (ACT) was the plaintiff in an action against the Virginia Highway Commission over the extension of Interstate 66 through Arlington, Virginia , having filed a suit in the U.S. District Court. The ESL model was used to produce calculations of air quality in the vicinity of the proposed highway. ACT won this case after a decision by the U.S. Fourth Circuit Court of Appeals. The court paid special attention to the plaintiff's expert calculations and testimony projecting that air quality levels would violate Federal ambient air quality standards as set forth in the Clean Air Act. Image File history File linksMetadata Download high resolution version (2592x1944, 1124 KB) Summary North-South Expressway towards Kuala Lumpur, South section, Melaka, Malaysia Copyright © 2006 mailer_diablo Licensing File links The following pages link to this file: Transportation in Malaysia Highway North-South Expressway Malaysian expressway system User:Mailer diablo/Gallery... Image File history File linksMetadata Download high resolution version (2592x1944, 1124 KB) Summary North-South Expressway towards Kuala Lumpur, South section, Melaka, Malaysia Copyright © 2006 mailer_diablo Licensing File links The following pages link to this file: Transportation in Malaysia Highway North-South Expressway Malaysian expressway system User:Mailer diablo/Gallery... The Arlington Coalition on Transportation (ACT) is a citizens group formed to oppose the construction of Interstate 66 through Arlington, Virginia. ... A plaintiff, also known as a claimant or complainant, is the party who initiates a lawsuit (also known as an action) before a court. ... Interstate 66 is an interstate highway in the eastern United States. ... Arlington County is a county located in the U.S. state of Virginia (which calls itself a commonwealth), directly across the Potomac River from Washington, DC. By an act of Congress July 9, 1846, the area south of the Potomac was returned to Virginia effective in 1847 As of 2000... District courts are a category of courts which exists in several nations. ... It has been suggested that Clean Air Act (1970) and Clean Air Act (1990) be merged into this article or section. ...

A second contentious case took place in East Brunswick, New Jersey where the New Jersey Turnpike Authority planned a major widening of the Turnpike. Again the roadway air dispersion model was employed to predict levels of air pollution for residences, schools and parks near the Turnpike. After an initial hearing in Superior Court where the ESL model results were set forth, the judge ordered the Turnpike Authority to negotiate with the plaintiff, Concerned Citizens of East Brunswick and develop air quality mitigation for the adverse effects. The Turnpke Authority hired ERT as its expert, and the two research teams negotiated a settlement to this case using the newly created roadway air dispersion models. East Brunswick is an suburban township located in Middlesex County, New Jersey. ... The New Jersey Turnpike is a toll road in New Jersey and is one of the most heavily traveled highways in the United States. ... This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ...

More recent model refinements

The CALINE3 model is a steady-state Gaussian dispersion model designed to determine air pollution concentrations at receptor locations downwind of highways located in relatively uncomplicated terrain. CALINE3 is incorporated into the more elaborate CAL3QHC and CAL3QHCR models. CALINE3 is in widespread use due to its user friendly nature and promotion in governmental circles, but it falls short of analyzing the complexity of cases addressed by the original Hogan-Venti model . CAL3QHC and CAL3QHCR models are available in Microsoft fortran and are limited to carbon monoxide: they do, however, include an embedded traffic model to better assess dynamic features such as stalling traffic. The above models are described in more detail on this website. Microsoft Corporation (NASDAQ: MSFT, SEHK: 4338) is an international computer technology corporation with 2005 global annual sales of close to $40 billion USD and about 64,000 employees in 85 countries and regions which develops, manufactures, licenses, and supports a wide range of software products for computing devices. ... Fortran (also FORTRAN) is a computer programming language originally developed in the 1950s; it is still used for scientific computing and numerical computation half a century later. ... Carbon monoxide, chemical formula CO, is a colorless, odorless, tasteless, flammable and highly toxic gas. ...

In addition, several new models have been developed that employ non-steady state Gaussian puff algorithms. The HYROAD dispersion model has been developed with National Cooperative Highway Research Program funding, incorporating ROADWAY-2 model puff and steady-state plume algorithms (Rao et al., 2002), in addition to the Federal Highways Administration's NETSIM traffic microsimulation model. Unfortunately, due to changes in the Windows operating system, the platform upon which HYROAD was developed, the NETSIM component of HYROAD can only operate on Windows 98 (or earlier) operating systems. The problem stems from the loss of the original model code for NETSIM by its developers, preventing it from being compiled on other operating systems. EPA contends that HYROAD is appropriate for modeling ambient concentrations of carbon monoxide, particulate matter, and air toxics. This power plant in New Mexico releases sulfur dioxide and particulate matter into the air. ...

The TRAQSIM model [1], developed with funding from the U.S. Department of Transportation's Volpe National Transportation Systems Center's Air Quality Facility also incorporates dynamic vehicle behavior with a non-steady state Gaussian puff algorithm. The United States Department of Transportation (DOT) is a Cabinet department of the United States government concerned with transport. ...

Recent Contentions Over Model Use

Recent health literature indicating that residents near major roads face elevated rates of several adverse health outcomes has prompted legal dispute over the responsibility of transportation agencies to use roadway air dispersion models to characterize the impacts of new and expanded roadways, bus terminals, truck stops, and other sources.

Recently, the Sierra Club of Nevada sued the Nevada Department of Transportation and the Federal Highways Administration over its their failure to assess the impact of the expansion of US-95 in Las Vegas on neighborhood air quality.[2] The Sierra Club asserted that a supplemental Environmental Impact Statement should be issued to address emissions of hazardous air pollutants and particulate matter from new motor vehicle traffic. The plaintiffs asserted that modeling tools were available, including the Environmental Protection Agency's MOBILE6.2 model, the CALINE3 dispersion model, and other relevant models. The defendants won in the U.S. District Court under Judge Philip Pro, who ruled that the transportation agencies had acted in a manner that was not "arbitrary and capricious," despite the agencies' technical arguments regarding the lack of available modeling tools being contradicted by a number of peer-reviewed studies published in scientific journals (e.g. Korenstein and Piazza, Journal of Environmental Health, 2002). On appeal to the 9th Federal Circuit Court, the court stayed new construction on the highway pending the court's final decision. The Sierra Club and the defendants settled out of court, setting up a research program on the air quality impacts of US-95 on nearby schools. According to the National Environmental Policy Act (NEPA) whenever the U.S. Federal Government takes a major Federal action significantly affecting the quality of the human environment it must first consider the environmental impact in a document called an Environmental Impact Statement (EIS). ... Particulates, alternately referred to as Particulate Matter (PM) , aerosols or fine particles are tiny particles of solid or liquid suspended in the air. ... EPA redirects here. ...

A number of other high-profile cases have prompted environmental groups to call for dispersion modeling to be used to assess the air quality impacts of new transportation projects on nearby communities, but to date the Federal Highways Administration has claimed that no tools are available, despite models and guidance available through EPA's Support Center for Regulatory Air Models (SCRAM).[3]

Among the more contentious of cases the Detroit Intermodal Freight Terminal and Detroit River International Crossing (Michigan, USA), and the expansion of Interstate 70 East in Denver (Colorado , USA).

In all of these cases, community-based organizations have asserted that modeling tools are available, but transportation planning agencies have asserted that too much uncertainty exits in all of the steps. A major concern for community-based organizations has been transportation agencies' unwillingness to define the level of uncertainty that they are willing to tolerate in air quality analyses, how that compares to the Environmental Protection Agency's guideline on air quality models, which addresses uncertainty and accuracy in model use.[4] EPA redirects here. ...

References

See also

• Atmospheric dispersion modeling
• Compilation of atmospheric dispersion models
• Air pollution dispersion modeling books

Atmospheric dispersion modeling is performed with computer programs that use mathematical equations and algorithms to simulate how pollutants in the ambient atmosphere disperse in the atmosphere. ... Atmospheric dispersion models are computer programs that use mathematical algorithms to simulate how pollutants in the ambient atmosphere disperse and, in some cases, how they react in the atmosphere. ... The information listed below for each of the air pollution dispersion modeling books includes the author(s), the publication date, the title, the edition, by whom published, and the ISBN or ISSN where available. ...

External links

• EPA Support Center for Regulatory Atmospheric Modeling
• EPA Preferred/Recommended Models
• EPA's Air Quality Modeling Group (AQMG)
• The Open Directory Project air dispersion modeling information.
• EPA's Air Toxics Risk Assessment (ATRA) Reference Library