Assessment of Urban Heat Island in the Phoenix Metropolitan Region

Urban heat island (UHI) is a phenomenon resulting from urbanization. Urbanization describes the process of transforming the natural landscape into one suited for human habitation and secondly the increase in the proportion of the people living in densely populated areas. These changes to the landscape result in a difference in the equivalent temperatures of the city and the surrounding natural (non-urbanized) area. Similar to other areas experiencing the impact of UHI, the City of Phoenix and its surrounding communities have experienced extensive economic growth and land use development in the last several decades. Natural landscapes have been replaced by roadways, buildings, and other new infrastructure. In the Phoenix region, UHI can cause temperatures to be much warmer than those in surrounding areas. According to the Environmental Protection Agency (EPA), a review of research studies and data found that on average in the United States, the UHI effect results in daytime temperatures in urban areas about 1–7°F higher than temperatures in outlying areas and nighttime urban temperatures about 2–5°F higher in outlying areas. In comparison, Phoenix nighttime low temperatures can be 10 to 15 degrees warmer than surrounding rural areas. ADOT and the MAG are considering how to maintain their existing freeway pavements and the influence of different pavement surfaces on the UHI is of interest. Specifically, the region must decide whether to continue the use of rubberized asphalt or replace it with an alternative treatment. One of those alternatives is to remove the existing rubber asphalt and convert the underlying concrete to the travel surface. The exposed surface will then have a diamond grind treatment. A number of efforts beyond just the UHI influence have been initiated to further inform this decision including: The Freeway Pavement Noise Reduction Analysis Study Freeway Noise Analysis Study Benefits and Cost Savings of DG vs. ARAC-FC Freeway Life Cycle Cost Analysis Freeway Surface Treatment – Peer Review The MAG Regional Council approved three projects for a diamond grind pilot program, developed by MAG and ADOT, in June 2020. As part of the pilot program, the projects will utilize a concrete-based diamond grind surface treatment instead of the rubberized asphalt overlay that has been used on the region’s freeway system for the last two decades. A current ADOT-MAG research project is analyzing the impacts of the diamond-grind surface treatment on air quality in the MAG region to enable informed decision-making. The agencies are now interested in research to better understand the relationships between roadway surface treatments and UHI. Research Objectives: Roadway pavements most likely play a large role in the UHI effect. Furthermore, different pavement types (i.e., concrete or asphalt) have different contributions to the UHI effect, Given the complexity of the issue with many unique variables, MAG and ADOT are interested in initiating a study to compare concrete pavements with the asphalt pavements on the UHI effect in the MAG Region. At a minimum, the research will: Observe the impact of urbanization and UHI under different urban and suburban land use types and at different geographic areas in the MAG planning region Quantify statistical relationships between UHI magnitude and land cover, specific to roadway surface treatments existing with the MAG planning region


    • English


    • Status: Active
    • Funding: $350,000
    • Contract Numbers:


    • Sponsor Organizations:

      Arizona Department of Transportation Research Center

      206 S. 17th Avenue
      ADOT Research Center
      Phoenix, AZ  United States  85007
    • Project Managers:

      Proffitt, David

    • Performing Organizations:

      Arizona State University

      660 S. College Ave
      PO Box 873005
      Tempe, Arizona  United States  85287
    • Principal Investigators:

      Neithalath, Narayanan

    • Start Date: 20220610
    • Expected Completion Date: 20251217
    • Actual Completion Date: 0

    Subject/Index Terms

    Filing Info

    • Accession Number: 01850659
    • Record Type: Research project
    • Source Agency: Arizona Department of Transportation
    • Contract Numbers: SPR-786
    • Files: RIP, STATEDOT
    • Created Date: Jun 29 2022 4:24PM