AIR QUALITY IMPACTS OF TRANSPORTATION AND LAND USE POLICIES

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1. Full citation and abstract?
  • McDonald-Buller, E.C., A. Webb, K. M. Kockelman, and B. Zhou. Air Quality Impacts of Transportation and Land Use Policies: A Case Study
    in Austin, Texas. 89th Annual Meeting of Transportation Research Board, Washington D.C., January 2010.
  • Abstract: "The impacts of land use and transportation policies on emissions, ozone concentrations, and a metric for population exposure were examined for Austin, Texas. Three distinct transportation and land use scenarios were investigated using a gravity-based land use model and a standard travel demand model: a business-as-usual scenario, a road pricing policy that included a flat-rate carbon-based tax and congestion pricing of all Austin area freeways, and an urban growth boundary policy. Two scenarios, a business-as-usual scenario and a flat-rate carbon-based tax 2 and congestion pricing policy were also investigated using a novel, parcel-level land use change and land use intensity model and a standard travel demand model. Transportation and land use policies were predicted to have substantial impacts on travel and emissions of ozone precursors. Emissions of ozone precursors decreased markedly for all 2030 scenarios due to the implementation of more stringent federal motor vehicle emission control programs, but transportation and land use policies were predicted to lead to even greater reductions of emissions of both ozone precursors relative to the business as usual scenario. The impacts of such policies on ozone concentrations and population exposure suggested varying effects. Lower exposure was typically predicted for the road pricing scenarios, but a penalty appeared to exist with relatively higher values of exposure predicted for the urban growth boundary on some episode days. The results of this analysis indicate the potential complexity of planning for urban growth and equity and the need for integrated modeling and policy evaluation efforts."

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.
  • Elena C. McDonald-Buller: Research Associate Professor at the Center for Energy and Environmental Resources at University of Texas at Austin
  • Alba Webb: Research Associate at the Center for Energy and Environmental Resources at the University of Texas at Austin
  • Kara M. Kockelman: Professor in the Department of Civil, Architectural and Environmental Engineering at the University of Texas at Austin
  • Bin Zhou: Assistant Professor in the Department of Engineering at Central Connecticut State University
  • The same Authors plus several more had submitted a much longer report to the EPA for a project from 2004 to 2008 titled "Predicting the Relative Impacts of Urban Development Policies and On-Road Vehicle Technologies on Air Quality in the United States: Modeling and Analysis of a Case Study in Austin, Texas" (2). This study spends more time explaining the models used and the technical aspects an average person wouldn't understand, and the newer study attempts to build off this one. Because of this, I used this study as a reference for information to understand the newer study.
  • The report also frequently references "Impacts of Urbanization on Emissions and Air Quality: Comparison of Four Visions of Austin, Texas," (1) and builds off some of the information in that report. McDonald-Buller and Webb worked on this report. However, I could not find this report available online anywhere.
  • The report also builds off the transportation work of Zhou and Kockelman. (3 & 4)

    1. Song, J., B. Parmenter, A. Webb, D. Allen, and E. McDonald-Buller, Impacts of Urbanization on Emissions and Air Quality: Comparison of
    Four Visions of Austin, Texas. EnvironmentalScience and Technology, Vol. 42, No. 19, 2008, pp.7294-7300.

    2. Webb, A., J. Song, D. Allen, E. McDonald-Buller, B. Zhou, S. Gadda, J. Lemp, S. Tirumalachetty, K. Kockelman, and B. Parmenter.
    Predicting the relative impacts of urban development policies and on-road vehicle technologies on air quality in the United States: A
    case 18 study in Austin, Texas. Final report submitted to the U.S. EPA. (STAR Grant No. RD83183901), December 2008.

    3. Zhou, B., K. Kockelman, and J. Lemp. Transportation and Land Use Policy Analysis using Integrated Transport and Gravity-based Land Use
    Models. Forthcoming in Transportation Research Record, 2009.

    4. Zhou, B. and K. Kockelman. Lessons Learned in Developing and Applying Land Use Model Systems: A Parcel-based Example. Forthcoming
    in Transportation Research Record, 2009.

3. What are the main findings or arguments presented in the article or report?
  • The conclusion of the report was that projections of vehicle miles traveled (VMT) in Austin in 2030 would be significantly reduced under road pricing and urban growth boundary policies, in comparison to a scenario in which there was no change in the current policies from now to 2030.
  • They also found that predicted reductions in emissions due to transportation and land use policies was even greater than the predicted reduction from the impending more stringent federal emission reduction programs from the EPA.
  • Affects of land and transportation policies had varying affects in regards to ozone concentrations and population exposure. The researchers concluded that this reflects the complexity required in urban planning for growth and the need for a better modeling and evaluation process.
  • VOC emissions remained similar to the 2007 base case and the 2030 scenario estimates.
  • Population exposure is lower for the road pricing scenario, but could be higher for the urban growth boundary scenario due to high population densities.

4. Describe at least three ways that the argument is supported.
  • Their arguments are supported statistically from their model results.
    • The business-as-usual scenario predicted by the models to have an 85 to 90% increase in vehicles miles traveled compared to a 2007 base case, while the increase was only 60% under road pricing and urban growth boundary policies.
    • The road pricing and urban growth boundary policies estimated to reduce emissions of ozone precursors by 15% more than under the business-as-usual scenario.
  • The model statistics only effectively support the report if the process for developing the models is justified. Each parameter included to the model is given a sufficient explanation to prove its a necessary component (and the same explanation is done for factors not included). For example:
    • Point source emissions can be assumed to be constant because they are comparatively small to other human sources of emissions.
    • Dry deposition is considered because it is the largest mechanism of air pollution loss for the area.
    • Note: well most explanations of variables seem legitimate with basic knowledge on air pollution, more specific justifications could be used. i.e. providing data to show that point source emissions are comparatively small.
  • By basing their models off previous studies with well received results, it helps to legitimize the points made in this report.

5. What three (or more) quotes capture the message of the article or report?
  • "Evaluating the impacts of urbanization on future emissions, air quality, and human exposure to pollution requires consideration of transportation, land use, and environmental policies, technological advances, and changes in demographics and human activity patterns" (pg 2).
  • "The results of this analysis indicate the potential complexity of planning for urban growth and equity and the need for integrated modeling and policy evaluation efforts" (pg 16).
  • "This project was conducted by a team with expertise spanning urban and regional planning, transportation and land use modeling, emission inventory development, air quality modeling and data analysis. [...] While expertise in these areas is not unique within the realm of many metropolitan planning organizations, departments of transportation, city governments, and state environmental agencies, there is a need for better collaboration between fields during community and regulatory decision-making processes to allow more comprehensive assessments of urbanization and its environmental impacts" (pg 16).
  • Beyond the search for correlations between pollutant concentrations and emissions and land use and transportation policies, these quotes show the more overarching goal of this report to expand and develop what's relevant when discussing air pollution.

6. What were the methods, tools and/or data used to produce the claims or arguments made in the article or report?
  • Travel conditions and household and employment distributions for 2030 for the Austin area were estimated using two integrated transportation-land use models (ITLUMs) that had been developed in the reports 3 & 4 above. Typical urban land use models
  • The first ITLUM utilizes gravity based land use model (G-LUM) and a travel demand model (TDM). The interactions between the these models are shown in the figure A below. EMPLOC is the employment allocation model, RESLOC is the residential allocation model, and LUDENSITY is the land use density model. EMPLOC outputs employment by category and zone, which serves as import for RESLOC. This then outputs predicted housing and employment levels by category, and inputs that into LUDENSITY. After allocating households, jobs, and estimating land consumption levels, the TDM is applied. This model predicts the spatial distribution of different household types and employment levels.
    gblum.pngluclui.png
  • The second ITLUM is land use change and land use intensity (LUC-LUI) model which is applied over the 5 county area, see figure B above. The LUC looks at small parcels of land, and determines how these individual parcels will evolve. It determines if they will break up into smaller parcels over time (the Subdivision model), the size of these parcels (Parcel Size model), and what land use types will emerge on each parcel (the Land Development model). Land use intensity levels are measured by household and employment counts, which the LUI outputs by type. The LUI sorts by travel analysis zones (TAZ) to provide input for the TDM.
  • These ITLUMs were performed in 5 year intervals to 2030, and three different transportation and land use scenarios were simulated. These 3 scenarios had previously been determined and research in source 2
  • Scenario 1: business-as-usual scenario (BAU), in which there is assumed to be no change in attitude or approach, and that current development trends would continue without any new policies imposed.
  • Scenario 2: congestion pricing-plus-carbon tax scenario (CPCT), includes a road pricing policy that included a flat-rate carbon-based tax and congestion pricing of all Austin area freeways
  • Scenario 3: urban growth boundary (UGB) scenario. This restricted new development to zones centered around existing population centers. Lands outside of these boundaries were not allowed to have residential, commercial, or any kind of development.
  • The first 2 scenarios were run through the G-LUM and the LUC-LUI. The third scenario was applied to the G-LUM and could not be applied to the LUC-LUI, because that economic and mathematical models were not adaptable to be set to specific zones.
  • The effects of urbanization patterns and the related vegetatative cover on an area's emissions were also considered. Global Biogenic Emissions and Interactions System (GloBEIS) version 3.1 was used to model vegetative cover.
    • parameters for GloBEIS include temperature, photosynthetically active radiation, wind speed, and humidity.
  • Dry deposition (acid rain) is the most prominent loss mechanism of air pollution in Texas, calling for the inclusion of a dry deposition algorithm.
  • Sources of point emissions have been small compared to other forms of emissions caused by humans in the region, so point emissions were assumed to be constant through 2030.

7. How (if at all) are health disparities or other equity issues addressed in the article or report?
  • "The five-county Austin – Round Rock Metropolitan Statistical Area (MSA) [...] is representative of many rapidly growing urban areas in the United States that are challenged with improving air quality that is on the cusp of attainment with the National Ambient Air Quality Standard for ozone while considering the spatial patterns and equity of future growth" (pg 3).
  • This addresses that population growth can magnify inequalities and should not just be viewed as an absolute economic benefit.

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?
  • The bibliography mostly includes articles with many authors that include some of the authors of this report, and attempts to tie together information from all 4 reports discussed in question 2.
  • The report was the final product of several reports produced primarily by professors and researchers University of Texas at Austin.
  • This report, as well as sources 1 and 2 received funding from the EPA (Source 2 received $650,000 in federal funding, couldn't find fund amount for this report or source 1).
  • The project period of source 2 began in 2004, and the final presentation of this report was in 2010.
  • This all indicates that this was a long term research project with federal funding, and done primarily within one group at University of Texas at Austin.

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?
  • Of the four sources I found that cited this article, two of them (1+4) were presented at Annual Meetings of the Transportation Research Board in the couple years following this report's presentation at the same annual meeting. This indicates that this meeting is an important event in the exchange of information and practices pertaining to the science in the transportation research community, and that attendees often work and produce off the work of others who attend and present.
  • When reading one of the earlier reports done by a group comprising of many of the same authors, (source 2 from question 2), it gave me important insight into how the different scenarios can be selected. This studies claims to use two approaches to evaluating urban growth scenarios, mathematical modeling and "visioning." Visioning is a process that is inclusive to the community and business owners to define transportation and urban goals. The urban growth scenarios evaluated in this previous study resulted from the visioning initiative with the Envision Central Texas in 2004.
    • "The ECT process engaged state and local government, business, environmental, and community development organizations, and elected leaders from the five counties. Based on information discussed in public workshops, the ECT process projected a set of four possible growth scenarios" (pg 3).
    • All scenarios were based on the population doubling in 20 to 40 years from 2001, but each assumed different spatial patterns of development.
    • If the same group of people used visioning for this study- why did they not use the same process for determining the transportation scenarios in this study? The study claims that all scenarios were reasonable for the area if they were pursued by community stakeholders, but give no information on what community stakeholders currently want to pursue.
  • (Reference quote used in question 8) The specific use of this study in the Canadian study interest me. The lack of definite results for some parameters after such a long research period for this topic and group originally seemed like a failure (i.e. variable results for different scenarios for ozone concentrations when ozone is the only NAAQS pollutant that does not meet standard in Texas). However, this study uses this to justify a need for more research, rather than a dismissal of the research already done.