Nikolaou, M., Jesse L. Buffington, Angel Herrera, Jr., and Hwang Inkeuk, “Traffic Air Pollution Effects of Elevated, Depressed, and at-Grade Level Freeways in Texas,” FHWA/TX-97/1327-4, Texas Transportation Institute, The Texas A&M University System, College Station, Texas 77843-3135, 1997
This report is one part of a larger study that aims to identify on the environmental, social, and economic impacts of freeway grades (either elevated, depressed, or at-grade). This part specifically focuses on the impact on air pollution. (defn: elevated roadways run above the surrounding terrain, depressed run below, and at-grade the roadway is level with the terrain).
2. Where do the authors work, and what are their areas of expertise? Note any other publications by the authors with relevance to the 6 Cities project.
Michael Nikolaou is an Associate Professor of Chemical Engineering at Texas Transportation Institute. His other research is not relevant to this project, as his major focuses are oil and gas production systems, semiconductor manufacturing tools and processes, and effective development and use of antibiotics. This is important to note which reviewing the report that the main author does not usually work with air pollution, but does often work on solving real world problems.
Jesse L. Buffington is a Research Economist at Texas Transportation Institute. He is a coauthor of a report titled "Attitudes, opinions, and experiences of business and institutional relocatees displaced by highways under the 1970 relocation assistance program." While this study does not focus on air pollution, it shows the authors continued research in the the direct and indirect impacts of transportation decisions.
Angel Herrera, Jr.is a Graduate Research Assistant at Texas Transportation Institute.
Hwang Inkeuk is a Graduate Research Assistant at Texas Transportation Institute.
Little information could be found on the internet about the last three authors.
3. What are the main findings or arguments presented in the article or report?
Comparisons between model predictions and measurements suggest that there is no evident reduction in air quality near depressed freeways.
In agreement with previous studies, elevated freeways are associated with slightly lower concentrations of carbon monoxide.
Data was compared to the impact prediction models that were used by the Texas DOT in 1995, CALINE and TXLINE. The researchers found that the Texas DOT should continue to use CALINE, but with modifications to the model.
4. Describe at least three ways that the argument is supported.
The report begins by establishing the importance and the relevance of the study.
The DOT is constantly updating highway systems in the state, especially in urban and suburban areas.
These improvements are made at varying grade levels, with the current trend during the time of the study (1997) favoring elevated and depressed sections to create more lanes.
These improvements received public opposition (for example, the proposed elevated section of the Dallas North Central Expressway). A flooding prior to the study of a depressed highway in Houston amplified public concerns.
Argument is insufficiently supported in many ways. Appendix B there includes graph showing CALINE model predictions vs measured CO levels for each day and site, there is no compilation of data for the reader to see a visual comparison between depressed, elevated, and at-grade sites. There are not even values provided to compare average depressed and elevated levels, just general sentences summarizing the findings.There are also no tables included for the TXLINE model.
Furthermore, the "Implementation" section recommends that the Texas DOT continue to use CALINE model with modifications, without specifically mentioning what those modifications are. It is mentioned that this model assumes smooth terrain surrounding the roadway.
5. What three (or more) quotes capture the message of the article or report?
"A preliminary search of the literature reveals very few case studies that have measured many of the social, economic, and environmental impacts of depressed and elevated freeways, especially those in Texas. Therefore, the highway decision-makers have very little relevant impact data to include in environmental assessment statements as support and to present at public hearings for proposed elevated and depressed sections of existing or proposed freeway" (pg 1).
Introduces the problem of the state making decisions without sufficient data to justify the decisions to the public.
"While the evidence provided by our studies is strong, we feel that a more thorough study would provide even more conclusive evidence, as follows: Data should be simultaneously collected on elevated, depressed, and at-grade sections of the same freeway. Provided that these freeway sections are not far apart from each other (so that traffic, landscape, and wind patterns could be the same), any differences in CO levels in the vicinity of each section of the freeway would be attributed to its configuration as elevated, depressed, or at-grade. [...] This kind of simultaneous collection of data at three locations of a freeway would require additional equipment (10 additional CO sensors and two additional weather stations) and personnel (two additional workers)" (pg 55).
While the arguments of the study were not well presented, this quote identifies an overarching message of the report. Many procedures were modified due to financial restrictions. This includes changing monitoring times dependent on when personnel are available and a reduction in monitors used, resulting in less than ideal spatial resolution. This is important to the project because it shows how realities can impact the development of science, and therefor impact the quality of information import decisions, such as on infrastructure, are based on. This study was sponsored by the Texas Department of Transportation in cooperation with US Department of Transportation Federal Highway Administration, yet funds, materials, and manpower remained an issue.
"Any highway improvement, regardless of grade level, not only impacts users but also impacts abutting and nearby property owners, businesses, and residents in some manner. Even the whole city or community is impacted in some way during and after construction."
6. What were the methods, tools and/or data used to produce the claims or arguments made in the article or report?
A survey was sent to all Texas DOT districts to locate all elevated or depressed freeway sections at least half a mile long the were planned, under construction, or constructed in the last ten years. 30 freeways were identified to fit this description, and TTI researches conducted site inspections at all 30 candidate locations for the study. 11 study locations were selected in the state, chosen to have a large mix in the characteristics grade level, location, abutting land use, and age. Of the selected, 8 were completed highways and 3 were under construction.
The method for this study involved was to conduct and before and after construction period analysis, supplemented with a cross sectional analysis at one point in time. The before and after study was to determine any affects caused by the freeway in air pollution, noise pollution, business activity, neighborhood cohesion. The point in time cross sectional reference is to compare metrics for these impact elements for elevated and depressed freeway grade levels.
Data to estimate the effects of different impact elements came from literature from previous studies, a national survey, the United States Census Bureau, the Texas State Comptroller and Employment Commission, TxDOT, Environmental Impact Statements (EIS) of each of the study sections, city criss-cross directories, site surveys of businesses and residents, traffic volumes and composition, air and noise levels, and drainage, erosion, and other environmental conditions.
The study looks at CO emissions on a microscale, over linear distances up to 100 m from the freeway.
Data was collected through continuous monitoring at one-minute intervals for at least three days at each study area. There were a minimum of 5 CO monitors put in a straight line along each highway being monitored.
Carbon monoxide levels were recorded as well as the following variables: wind speed and direction (horizontal and vertical components), temperature, barometric pressure, relative humidity, solar radiation, traffic vehicle count, traffic mix (cars, trucks, buses, light- vs. heavy-duty), and average vehicle speed.These variables were required to use an inputs to compare the measured data to existing model predictions.
The proposed sampling period for monitoring was 10 hours per day from 8 am to 6 pm. From the day 1 data, the times of day resulting in peak CO levels were determined to see if the window needed to start any earlier or later. Sampling was only done on weekdays to properly account for commuter emissions.
Data was then compared to CALINE and TXLINE models.
7. How (if at all) are health disparities or other equity issues addressed in the article or report?
Health is not directly mentioned in the report, but the general premise is highly related to equity issues. The introduction of the problem examined in the study discusses public backlash at transportation decisions, and then the larger overarching study investigates the economic, environmental, and social impacts these decisions made by the government impact the surrounding area and its inhabitants.
The results of the study imply that when investigating grade modifications of a highway, their is no decrease in air quality for depressed areas for nearby residents and slightly better CO levels on elevated highways, both compared to at-grade highways.
This study considered nearby land use, and the study could have been improved by collecting data for areas with similar land use and no highway, rather than only using an at-grade highway as the control.
8. Where has this article or report been referenced or discussed? (In some journals, you can see this in a sidebar.)
I was only able to found one other report that cited this study, California Environmental Protection's Air Resources Board report, "Status of Research on Potential Mitigation Concepts to Reduce Exposure to Nearby Traffic Pollution" in 2012.
This quote related to the elevation/ depression of roadways:"Studies of elevated and below-grade roadways and freeway caps (also called freeway decks, lids or covers), which are covers over a sunken roadway that produce a road tunnel, also were reviewed, but studies were limited and results variable, and these measures are not feasible or are impractical for most new housing developments" (pg 4). This indicates that this study did not have a substantial impact on the transportation field.
9. Can you learn anything from the article or report’s bibliography that tells us something about how the article or report was produced?
Various studies are cited and referenced as literature on previous studious on elevated and depressed freeways and experimental databases for modeling pollutant dispersion. For databases, they determined that the only one with sufficient results to determine equipment error was conducted by Bullin, et al, for Texas A&M. Monitor placement for the study was also based upon results of Bullin and colleagues, and 3 different reports by Bullin are cited which were all TTI. This shows that the study was strongly developed as a continuation of TTI research while dismissing the results of most other related reports.
10. What three points, details or references from the text did you follow up on to advance your understanding of how air pollution science has been produced and used in governance and education in different settings?
This report was only one part of multiple reports on the affects of elevated and depressed highways, so I reviewed the other reports. The other three reports focused on traffic noise affects, land value and land use effects, and social and economic effects.Conducting separate reports on different impact aspects is a fairly unique approach to research, and could lead to a more holistic view of air pollution.
The CALINE model was developed by the California state transportation agency. Its popularity in government agencies is often contributed its user friendly nature, despite the fact that there are more complex and accurate models available.
The Sierra Club recently sued the Nevada Department of Transportation due to a failure to assess the impact of route 95 expansion in Las Vegas, and availability of modeling tools, specifically CALINE, was used as an argument against the defendants.
2. Where do the authors work, and what are their areas of expertise? Note any other publications by the authors with relevance to the 6 Cities project.
3. What are the main findings or arguments presented in the article or report?
4. Describe at least three ways that the argument is supported.
5. What three (or more) quotes capture the message of the article or report?
6. What were the methods, tools and/or data used to produce the claims or arguments made in the article or report?
7. How (if at all) are health disparities or other equity issues addressed in the article or report?
8. Where has this article or report been referenced or discussed? (In some journals, you can see this in a sidebar.)
9. Can you learn anything from the article or report’s bibliography that tells us something about how the article or report was produced?
10. What three points, details or references from the text did you follow up on to advance your understanding of how air pollution science has been produced and used in governance and education in different settings?