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Road pavement is a known contributor to the urban heat island effect. Several vendors are providing engineered pavements coatings—known as “cool pavement”—to reflect light and, therefore, reflect heat to reduce the thermal load of roads. Few of these cool pavements have been evaluated outside lab conditions, where they tend to rely heavily on surface temperature measurements with the assumption that lower surface temperatures result in lower ambient air temperatures in real-world practice. Further, while heat is detrimental to the pedestrian and cyclist experience and health, almost no research exists documenting the experience of the cool pavement on active travelers, including their perception of heat. The City of Tucson conducted a pilot application of the PlusTi asphalt rejuvenator, a cool pavement product, in 2021 as a part of its Parks and Connections Bond work. We conducted a before-after, case-control quasi-experimental design to evaluate the impacts of the cool pavement product on heat metrics, including surface temperatures (TS) of the pavement, ambient air temperatures (TA) of the area, and thermal comfort as measured by wet bulb globe temperature (WBGT). The study design did not allow us to test for before-and-after treatment differences in TS, as other factors likely contributed to observed differences. Once autocorrelation is accounted for, we estimated the PlusTi pavement rejuvenator resulted in 0.3°F less TA observed and no statistical difference measured in WBGT.


This is a final report, NITC-RR-1483, from the NITC program of TREC at Portland State University, and can be found online at:



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Appendix A - Working Paper Literature Review.docx (124 kB)
.doc file - Literature Review

Appendix B - Kestrel Summary Statistics.csv (36 kB)
.csv file - HourlySumStats_AprOct_Long

Appendix C - 12_05_Kestrel_Cleaning_ONLY.R (38 kB)
.R file -Scripts to Process and Summarize Kestrel Data (

Appendix C - Kestrel_AprOct_Cleaned_File_v5_Fixing_Kestrel.R (82 kB)
.R File -Scripts to Process and Summarize Kestrel Data_Cleaned_File