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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Impacts of wind fields on the distribution patterns of traffic emitted particles in urban residential areas</title>
      <link>https://trid.trb.org/View/1594384</link>
      <description><![CDATA[Traffic emissions are a major contributor to urban atmospheric pollution. The wind fields also play an important role in the dispersion of air pollutants from the traffic emissions. However, the effects of different regional wind fields on the diffusion patterns of traffic-emitted fine particulate matter (PM₂.₅) in urban areas are still unclear and lack quantified measurements. To provide guidance to urban planning and design, as well as urban governance and management, it is especially important to identify the extent to which wind fields affect the diffusion of traffic-emitted particles. To understand the effect, field measurements and numerical simulations were conducted in this study. The field measurements mainly focused on collecting three-dimensional (3D) distributions of concentrations of traffic-emitted particles in a student dormitory zone at a university using instrumented unmanned aerial vehicles (UAVs). The collected PM₂.₅ measurements were used to verify and calibrate numerical models. Then, computational fluid dynamics (CFD) simulations were used to track the progress of pollutant dispersion and evaluate its relationship to urban forms. The effects of different wind directions (northwest and southeast) on the distribution and deposition of the traffic-emitted particles in the residential area were studied under different wind velocity conditions (1 m s−¹, 5 m s−¹ and 20 m s−¹). As efficient observation platforms, the UAVs employed in the study allowed the capture of the 3D variations in the distributions of atmospheric pollutants in urban areas. The result provides a better understanding of the dispersion of atmospheric pollutants in a specific urban built environment under different wind fields, which can support urban governance and planning and design practice leading to effective mitigation of traffic-induced air pollution in urban areas.]]></description>
      <pubDate>Fri, 29 Mar 2019 10:15:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/1594384</guid>
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    <item>
      <title>Research on CO dispersion of a vehicular exhaust plume using Lattice Boltzmann Method and Large Eddy Simulation</title>
      <link>https://trid.trb.org/View/1464724</link>
      <description><![CDATA[The exhaust gas dispersion from the vehicles has a direct impact on human health, particularly on vehicle drivers, passengers, and people nearby. Because of the numerical implementation simplicity and well captured solution for fluid dynamics around multiple bodies, Lattice Boltzmann Method (LBM) has been adopted in lots of domains during the last two decades. This paper combines LBM together with Large Eddy Simulation (LES) turbulence model to study exhaust gas emission and dispersion characteristics. Carbon monoxide (CO) relative concentration and velocity distribution from a vehicular exhaust plume in the near-wake region is investigated for low and high idling driving conditions under different ambient wind speeds. Validation has been made to test the performance of gas simulation of the LBM-LES method in XFlow, after which 3D simulation of exhaust gas dispersion is considered, and the time-averaged CO relative concentration and velocity are analyzed. Results indicate that flow wake by ambient wind can affect the dispersion of exhaust gas. The exhaust gas moves downstream and spread to a wider range under higher ambient wind speed. While, the flow field becomes complicated due to the interflow effect when the wind speed and exhaust gas velocity are close, which enhances the dispersion characteristics of exhaust gas to a certain extent.]]></description>
      <pubDate>Thu, 25 May 2017 13:56:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/1464724</guid>
    </item>
    <item>
      <title>Methods of air traffic management in the airport area including the environmental factor</title>
      <link>https://trid.trb.org/View/1442511</link>
      <description><![CDATA[In the modern approach to air traffic management (ATM), issues related to air quality and climate protection have led to the introduction of a growing number of new restrictions instead of having these issues be the objectives of actions taken. The aim of the study was to investigate whether it is possible to improve air quality while controlling pollution emission by introducing changes in the organization of air traffic control at the airport. For this purpose, mathematical models of emissions were created. These concern the movement of aircraft near the airport and emission of carbon dioxide and the spread of human health related substances emitted from a landing airplane's engine. The first case refers to the possibility of using different arrival procedures. The second case was to adapt the Pasquill formula by treating landing aircraft as a sequence of point-source emissions. As a result of applying the designed models and software tools, it was proven that both a change in the arrival trajectory and a change of the runway can contribute to a reduction of CO₂ emission into the atmosphere. The emission maps created for different aircraft approach profiles show the ability to control the local concentration of harmful emissions. The study clearly shows that the current approach of maximizing throughput is not beneficial to air quality. ATM services should consider the use of other variants of air traffic organization, particularly during periods of reduced traffic.]]></description>
      <pubDate>Mon, 27 Mar 2017 09:34:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/1442511</guid>
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    <item>
      <title>Modeling Dispersion from Toxic Gas Released After a Train Collision in Graniteville, SC</title>
      <link>https://trid.trb.org/View/814481</link>
      <description><![CDATA[After two Norfolk Southern freight trains collided in January 2005, state and local agencies were provided with meteorological and atmospheric modeling and consequence assessment support through the Savannah River National Laboratory (SRNL) Weather Information and Display System. Several toxic chemicals, including chlorine, were released into the environment as a result of the collision. Nine fatalities and more than 500 injuries resulted from the dense and highly toxic chlorine gas cloud that formed in the accident's vicinity. Shortly after SRNL received an assistance request, emergency managers in the county's Unified Command Center had ongoing release forecast path depictions through transport model results made available to them. Over the ensuing two days of active response, support continued. Savannah River Site (SRS) dispatched hazard material  teams, and responders from Department of Energy headquarters, SRS Emergency Operations Center, and the South Carolina Department of Health and Environmental Control, were also provided transport/consequence assessment model results and weather briefings by SRNL. During the accident response, there was provision, at 2-km horizontal grid spacing, of operational model-generated forecast winds used, during the incident, in consequence assessments. To examine local topography's potential influences on plume migration in greater detail, high-resolution Regional Atmospheric Modeling System (RAMS, version 4.3.0) simulation was later performed. Using multiple grids with an innermost 125 m grid spacing, meteorology was determined using the detailed RAMS simulation. Two simulation results show that there is general agreement with meteorological observations at the time; area wind was not significantly affected by local topography as a consequence. Agreement with immediate area fatalities and visible vegetation damage was indicated by localized plume behavior simulation through a dense gas dispersion model using higher resolution winds.]]></description>
      <pubDate>Thu, 23 Aug 2007 13:00:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/814481</guid>
    </item>
    <item>
      <title>Atmospheric Effects in ISO 9613-2</title>
      <link>https://trid.trb.org/View/813721</link>
      <description><![CDATA[This paper describes how refraction by wind, temperature, and humidity gradients in the atmosphere can dramatically impact sound propagation and therefore play an important role in determining annoyance from noise emissions. When refraction is upward, lower annoyance is expected because the sound energy is directed away from ground-based receivers. Downward-refracting conditions, on the other hand, tend to raise near ground sound levels and therefore potentially lead to higher annoyance. Besides refraction, the atmosphere produces other important effects on sound propagation, such as temperature and humidity dependent absorption, scattering of sound energy into refractively and topographically formed shadow regions, and random variations in received sound levels. Although the basic physical mechanisms affecting sound propagation in the atmosphere are thought to be well understood, it has proven difficult to develop and agree upon comprehensive, workable engineering approaches to quantify the propagation effects. Among the many reasons for this state of affairs, perhaps the following are most important: (1) many complex interacting phenomena affect the propagation, and it is exceedingly difficult to develop good models for these phenomena working in conjunction. For example, although good theoretical solutions exist for sound diffraction over a barrier in a homogeneous atmosphere, in practice these solutions have limited applicability because of interaction of the atmospheric flow with the barrier, varying ground surfaces in the vicinity of the barrier, etc; (2) for all but very simple scenarios, the physical equations governing the propagation cannot be practically solved across a broad range of frequencies, even with modern computational capabilities; (3) the structure of the real-world environment (atmosphere, terrain, and man-made objects) is quite complicated and cannot typically be characterized with the resolution necessary to predict propagation accurately; and (4) the atmosphere varies over time scales from seconds to seasons (and longer), and therefore it is difficult to extrapolate or generalize the results of a few calculations]]></description>
      <pubDate>Fri, 27 Jul 2007 07:06:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/813721</guid>
    </item>
    <item>
      <title>The Pecularities of Fine Particles Dispersion over the Roadside</title>
      <link>https://trid.trb.org/View/809399</link>
      <description><![CDATA[A physical model of ground-level mathematical distribution was developed for determining pollutant dispersion peculiarities on freeways. Correlation of Lithuanian and foreign studies of ultrafine particles and transition metal measurements data was used for model reasoning. It was defined that the deposition rate of fine particles and aerosols, which are transporting metals, is the same: approximately 2 cm/sec within 60 m of the road. This means that ultrafine particles due to the moisture, precipitation, wind, and coagulation in the natural geographic environment, have about 100 times higher deposition rate than expected based on their diameter. Considering the peculiarities of the model applied, pollutant concentration above the ground surface in the aforementioned distance from the road could be decreased by the same means as in the vicinity of the freeway: planting high impervious belts of trees and bushes.]]></description>
      <pubDate>Wed, 30 May 2007 15:05:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/809399</guid>
    </item>
    <item>
      <title>Atmospheric Dispersion Study of Deicing Salt Applied to Roads: Part II Final Report for Period July, 2002 to June, 2004</title>
      <link>https://trid.trb.org/View/782488</link>
      <description><![CDATA[This report describes results from a project to characterize the atmospheric emission and deposition of deicing road salt composed mainly of sodium chloride (NaCl).  The focus of the effort has been to determine the airborne concentrations and deposition of road salt aerosol due to the proposed construction of a roadway, FAP 340, which would join Interstate 55 (I-55) and Interstate 80 (I-80) southwest of Chicago.  Five monitoring sites were established to characterize the road salt deposition.  The report gives an overview of the sampling sites, presents data from the different instruments deployed at the sampling sites, and describes a model developed for the study to simulate salt deposition.  The road salt model is the combination of an emissions model and a deposition model.  The deposition parameterization is based on measurements following several snow events of salt collected in snow samples at different distances along I-55, which show the salt deposition to essentially vary inversely with the distance from the roadway.  The emissions model is based on an assumed exponential decay with time of emissions from a roadway for which the start time and decay rate of emissions were determined from wind-directed measurements of the salt deposition at the different sampling sites.  The initial emission rate is determined by applying the emission model and recorded wind direction measurements with time for the periods following the snow events after which the snow samples were collected.  Finally, the annual deposition in the road salt model is computed as the average deposition pattern from different snow events using the above parameterization and recorded measurements of the wind direction with time scaled to the annual number of snow events.  Results of the model are compared to measurements of deposition at the five sampling sites and the model is applied to simulate the deposition patterns following construction of FAP 340.]]></description>
      <pubDate>Thu, 25 May 2006 18:18:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/782488</guid>
    </item>
    <item>
      <title>Improvement of Ash Cloud Information by Tokyo VAAC</title>
      <link>https://trid.trb.org/View/757196</link>
      <description><![CDATA[The Tokyo Volcanic Ash Advisory Center (VAAC), operated by the Japan Meteorological Agency (JMA), monitors satellite imagery and obtains foreign and domestic reports on volcanic activities.  The Tokyo VAAC issues volcanic ash advisories (VAAs) if volcanic ash is likely to affect any air routes in Asia or the Western Pacific area.  These VAAs contain information on the present status and forecasts of future dispersion of the volcanic ash clouds.  The information is in the graphical and text format used by civil aviation authorities and by Meteorological Watch Offices.  The paper discusses the automatic issuance of VAAs for volcanoes in Japan, improvement of the forecast precision of volcanic ash cloud dispersion, and the Tokyo VAAC website that is now open to the public.]]></description>
      <pubDate>Thu, 30 Jun 2005 10:56:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/757196</guid>
    </item>
    <item>
      <title>Volcanic Cloud Conceptual Models for Volcanic Ash Advisory Centre Operations</title>
      <link>https://trid.trb.org/View/756968</link>
      <description><![CDATA[A basic approach to factual uncertainty in operational meteorology is to develop conceptual models and related procedures that encourage fast diagnosis of the nature of an event, the degree of risk, and the action required.  Volcanic Ash Advisory Centre operations are hindered by imperfect remote sensing, few reliable direct observations, and limited ground-based monitoring.  The concentration of maximum ash, cloud evolution, height of rise of a volcanic cloud, detectability of the cloud, and the rate of ash deposition are all greatly dependent on the meteorological environment.  This paper uses aircraft and ground based video observations from the Philippines and Japan, and remote sensing of the Pinatubo volcano's volcanic thunderstorms.  Particle radius measurement techniques and results from the Active Tracer High Resolution Atmospheric Model are described and relative particle concentrations, modes of volcanic convection and plume dispersal are discussed.]]></description>
      <pubDate>Fri, 24 Jun 2005 13:55:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/756968</guid>
    </item>
    <item>
      <title>NOAA's NWS Volcanic Ash Program: Current Status and Plans for the Future</title>
      <link>https://trid.trb.org/View/756688</link>
      <description><![CDATA[The National Oceanic and Atmospheric Administration (NOAA) operates four Meteorological Watch Offices (MWO) and two of the world's nine Volcanic Ash Advisory Centres (VAACs), and as such, plays an important role in the worldwide volcanic ash network.  The International Civil Aviation Organization (ICAO) defines the operational responsibilities of the two VAACs.  The National Weather Service's (NWS) Alaska Aviation Weather Unit manages the Anchorage VAAC.  The NWS's National Centers for Environmental Prediction (NCEP), the National Environmental Satellite, and the Data and Information Service (NESDIS) Satellite Analysis Branch jointly manage the Washington VAAC.  All of these centers together are responsible for providing ash dispersion forecasts and volcanic ash advisories for an area that ranges widely from the Pacific Ocean eastward over the United States and much of the Atlantic Ocean.  This presentation explores NOAA's Volcanic Ash Program.  It discusses future plans and the current status in the areas of research and development, operations, and policy development.]]></description>
      <pubDate>Mon, 20 Jun 2005 09:44:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/756688</guid>
    </item>
    <item>
      <title>FALL3D: A Numerical Model for Volcanic Ash Dispersion in the Atmosphere (Abstract Only)</title>
      <link>https://trid.trb.org/View/756502</link>
      <description><![CDATA[Reliable computational models are necessary to figure out how a particular volcanic ash cloud will disperse, and thus possibly come into contact with an aircraft in flight.  Engine failure can be the outcome when airplanes encounter an unexpected volcanic ash cloud.  This paper presents a new Eulerian model to simulate the dispersion and depositing of volcanic ash.  The model is called FALL3D.  The model is based on the solution of an advection-diffusion-settling equation, together with a Limited Area Model (LAM) for the wind field, and a parameterization of the turbulent diffusivity tensor based on the K-theory.  The model inputs are the meteorological field data provided by the LAM, the topography, the settling velocity distribution of volcanic ash, and the mass eruption rate.]]></description>
      <pubDate>Tue, 14 Jun 2005 12:52:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/756502</guid>
    </item>
    <item>
      <title>Volcanic Ash Dispersion Modeling Research at NOAA Air Resources Laboratory</title>
      <link>https://trid.trb.org/View/756623</link>
      <description><![CDATA[This paper discusses research on the Hybrid-Single Particle Lagrangian Integrated Trajectories (HYSPLIT) model that the National Oceanic and Atmospheric Administration (NOAA) is conducting, to improve guidance for volcanic ash forecasting.  Preliminary results of one project suggest an archive of dispersion forecast patterns and trajectory forecasts from hypothetical analysis dispersion patterns and corresponding hypothetical eruptions can be used to predict the reliability of subsequent forecasts.  Ensemble meteorology is utilized in another project to create a prototype of a product of probabilistic forecasting.]]></description>
      <pubDate>Tue, 14 Jun 2005 12:52:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/756623</guid>
    </item>
    <item>
      <title>Predicting Regions Susceptible to High Concentrations of Airborne Volcanic Ash in the North Pacific Region (Abstract Only)</title>
      <link>https://trid.trb.org/View/756582</link>
      <description><![CDATA[Volcanic ash clouds from 22 of the 100 historically most active volcanoes in the North Pacific (NOPAC) region have been simulated in order to generate airborne ash probability distribution (AAPD) maps to display the distribution of airborne volcanic ash in the region.  The PUFF ash-dispersion model was executed daily utilizing archived wind field data between 1994-1995 and 1997-2001 for high and low aircraft flight levels.  The AAPD maps suggest that volcanic eruptions that originate from the Kamchatkan Peninsula would travel due east into the NOPAC air traffic routes during the summer.  Wind directions over the Kamchatkan Peninsula are more variable during the winter, which results in a bimodal ash distribution.  On the other hand, AAPD maps indicate that volcanic eruptions that originate from the Alaskan Peninsula and the Aleutians are more likely to travel east-northeast during the winter and southeast during the summer.  The upper atmospheric region that is generally centered over the heavy air traffic flight corridor of the NOPAC, and is most likely to contain airborne ash, is located off the eastern coast of the Kamchatkan Peninsula.]]></description>
      <pubDate>Tue, 14 Jun 2005 12:52:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/756582</guid>
    </item>
    <item>
      <title>USING A DISPERSION MODEL TO ESTIMATE EMISSION RATES OF PARTICULATE MATTER FROM PAVED ROADS</title>
      <link>https://trid.trb.org/View/667694</link>
      <description><![CDATA[This paper reports on a series of measurements carried out from January 1996 to June 1997 to estimate emissions of PM sub(10) from paved roads in Riverside County, California. The program involved the measurement of upwind/downwind vertical profiles of PM sub(10), in addition to meteorological variables such as wind speed and vertical turbulence. This data was analyzed using a new dispersion model that incorporates current understanding of micrometeorology and dispersion. The emission rate was inferred by fitting model predictions to measurements. Inferred emission factors ranged from 0.2 g VKT sup(-1) for freeways, to about 3 g VKT sup(-1) for city roads. The uncertainty for these factors is estimated to be approximately a factor of 2. At this stage, the best estimate of emission factor lies between 0.1 and 10 g VKT sup(-1). Measured silt loadings were found to be poor predictors of emission factors. Measured emission factors imply that paved road emissions may contribute about 30% to total PM sub(10) emissions from a high traffic area such as Los Angeles. This suggests that it is necessary to develop methods more reliable than the upwind-downwind concentration difference technique.]]></description>
      <pubDate>Thu, 21 Sep 2000 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/667694</guid>
    </item>
    <item>
      <title>ASSESSING THE REPRESENTATIVENESS OF MONITORING DATA FROM AN URBAN INTERSECTION SITE IN CENTRAL LONDON, UK</title>
      <link>https://trid.trb.org/View/667696</link>
      <description><![CDATA[The wind flow field around urban street-building configurations has an important influence on the microscale pollutant dispersion from road traffic, affecting overall dilution and creating localized spatial variations of pollutant concentrations. As a result, air quality measurements made at different urban monitoring sites can be strongly dependent on the interaction between the local wind flow field with the street-building geometry surrounding the monitor. This study is an initial attempt to develop a method for appraising the significance of air quality measurements from urban monitoring sites, using a general application computational fluid dynamics (CFD) code to simulate small-scale flow and dispersion patterns around urban building configurations. The aim of the work was to evaluate routine CO monitoring data collection by a municipal entity at an intersection of street canyons in central London. With the use of simple CFD simulations and the analysis of available monitoring data, it was possible to gain insights into the effect of wind direction on the small-scale dispersion patterns at the chosen intersection, and how that can influence the data captured by a monitor. It was found that a change in wind direction could result in an increase or decrease of monitored CO concentration of up to 80%, for a given level of traffic emissions and meteorological conditions. Understanding and de-coupling the local effect of wind direction from monitoring data using the methods presented in this work could prove to be a useful new tool for urban monitoring data interpretation.]]></description>
      <pubDate>Thu, 21 Sep 2000 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/667696</guid>
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