Completed traffic analysis, emissions modeling, and dispersion modeling for Federal Highway Administration (FHWA) Division Offices and State Departments of Transportation on several high-profile highway projects – many facing or in litigation. Two projects of note that involved refined hot-spot air dispersion modeling analysis were the Central 70 project in Denver, CO and the Centennial Corridor project in Bakersfield, CA. Other projects of note that involved quantitative mobile source air toxics (MSAT) analysis were the I-93 project in NH; the Intercounty Connector project in MD; the US 395 project in Spokane, WA; and the Northwest Corridor project in Atlanta, GA. Due to the critical nature of some of these projects, occasional briefings of senior-level management were required, plus interactions with legal staff. Work on several of these projects was recognized by receipt of individual and group FHWA awards.
Provided technical assistance to the FHWA Office on Natural Environment in modernizing FHWA’s Guidance on Mobile Source Air Toxic Analysis in National Environmental Policy Act (NEPA) Documents. Emissions modeling of MSAT compounds for representative project alternatives was completed to establish recommended thresholds for conducting quantitative analyses.
Led a work group to modernize the CAL3 series of highway air dispersion models (i.e., CALINE3, CAL3QHC, and CAL3QHCR). The effort resulted in the development of the FHWA Highway Air Dispersion (FHWA) model. The model underwent rigorous testing during development; subsequent statistical evaluation by comparing model predictions to tracer gas measurements; and application by example through a series of case studies based on actual projects. A Model Formulation and Evaluation document and Model User Guide were prepared.
Served on a collaborative work group with the U.S. Environmental Protection Agency (EPA) on developing particulate matter hot-spot guidance and developing and delivering training on implementing the guidance in Atlanta, GA; Sacramento, CA; Seattle, WA; and Phoenix, AZ.
Team member in a research project to develop a nationwide training course entitled “Fundamentals of Air Quality for Highway Planning and Development” for FHWA. Four course modules were authored, pertaining to air quality assessment using highway air dispersion modeling.
Performed an air quality assessment for the proposed upgrading of Georgia State Route 400 in Atlanta, GA. This highway is the main transportation corridor providing access from north Fulton County to Perimeter Center, Buckhead, and downtown Atlanta. Line source emissions and dispersion modeling was performed to predict carbon monoxide (CO) concentrations along the proposed project corridor and 3 signalized intersections associated with the project. A case analysis of historical meteorology and ambient monitoring data was carried out to characterize the dispersion conditions that occur on days when highest ambient CO concentrations were measured in the project area.
Investigated a dense fog event on a bridge across a lake in northeast Texas. The lake is used as a cooling lake by a nearby electric power plant to release waste heat into the atmosphere. As the waste heat is dissipated, some of the lake water evaporates. When the warm, moist air rises, it mixes with colder air above. Under certain meteorological conditions, the water vapor in the air can condense into tiny droplets causing “steam fog” on the lake. The cooling lake can initiate fog events or intensify natural fog events to cause restricted visibility on the bridge. Expert testimony was provided in two court cases pertaining to a serious automobile accident that occurred on the bridge.
Assessed the air quality impact of a major toll road in Atlanta. Compliance with air quality standards was determined based on a combination of ambient air monitoring and line source dispersion modeling for CO and lead emissions. At the time, the U.S. EPA guideline model was not applicable for predicting CO concentrations near signalized intersections operating at over-capacity conditions. Consequently, the Georgia Intersection Model was developed for that purpose. Model predictions were compared to ambient air quality measurements made at an intersection near the project corridor. The results of the analysis were presented to the U.S. EPA in Research Triangle Park (with the direct involvement of the Commissioner of the GA DOT and the FHWA GA Division) and the methodology was approved for use in the assessment. The results of the assessment were included as part of the Environmental Impact Statement to satisfy the requirements of NEPA.
Evaluated the ventilation requirements for a vehicular tunnel under the planned Atlanta Financial Center on the right-of-way of Georgia State Route 400. The primary design criterion was to maintain acceptable CO concentrations within the tunnel in the event of a major traffic stoppage. Secondly, the minimum ventilation required for fire protection was determined. The feasibility of natural ventilation in providing the design ventilation rate was examined. An emergency mechanical ventilation system was specified to provide the design ventilation rate in the event of an accidental spill of hazardous chemicals from a tanker truck in the tunnel.
Assessed the ambient air quality expected at a proposed transit station in the median of a major multilane highway in Atlanta, GA. The minimum ventilation rate for the station was specified based on predictions of maximum air pollutant concentrations resulting from the operation of motor vehicles on the adjacent highway. Furthermore, since air rights over the transit station could be sold, the minimum ventilation system requirements were computed assuming the station would be in a vehicular tunnel.
Managed an 18-month study to quantify the accuracy and precision of air dispersion models used nationally to predict CO emissions from automobiles and its subsequent dispersion in the ambient air near an urban freeway and an urban arterial signalized intersection. Two separate field experiments were designed and conducted over a 6-month period, operating 18 monitoring stations at 2 locations in Chicago, IL. Extensive CO, meteorology, traffic, and tracer release measurements were collected concurrently for use in the model predictions. Results of this study were presented at the Annual Meeting of the Transportation Research Board and published in Atmospheric Environment. Subsequently, the U.S. EPA used the field data to evaluate their CAL3QHC line source dispersion model and Caltrans used the field data in their development of the CALINE4 model.
Evaluated the air quality impact of a proposed 6-level parking deck providing 1530 parking spaces for state employees and visitors of the Capitol complex in Raleigh, NC. Mobile source emissions and air dispersion modeling was performed for receptors located near the parking deck; near two signed intersections to be constructed to provide access to the parking deck; and near two signalized intersections affected by the project.
Completed an air quality impact assessment of the proposed relocation of three major rail routes through Augusta, GA. Ambient (local plus background) concentrations of particulate matter, sulfur oxides, hydrocarbons, carbon monoxide, and nitrogen oxides were determined due to emissions from locomotives; switch engines in rail yards; and queuing automobiles at railroad/street grade crossings. Twelve rail system alternatives were evaluated for the build and no-build condition for three different time periods.
Assessed the potential for fog occurrences on the proposed Cooper River crossing of the Mark Clark Expressway in North Charleston, SC. An ambient air monitoring and dispersion modeling study was performed to assess the frequency and severity of foggy conditions near a proposed bridge adjacent to a kraft paper mill, which is a large industrial source of water vapor emissions. A computer model was developed to predict the likely number of hours per year of fogging and icing on the bridge. Model predictions were compared to on-site measurements. The study was performed in support of a court case.