A Multilayered Evaluation of Reflective Pavement: Insights from a Pilot Study in Austin, Texas

The urban heat island (UHI) phenomenon occurs when cities are hotter than their surrounding rural areas due to an increase in man-made materials such as concrete and asphalt. These surfaces alter the surface energy balance and result in a positive thermal balance in the urban environment because of the increased heat gains like the high absorption of solar radiation and anthropogenic heat, and the decreased thermal losses. This increase in urban heat can lead to a myriad of negative effects ranging from increased energy costs, to an increase in deaths from overheating. Thus, many cities have begun attempting to mitigate extreme heat within their municipalities. One novel approach has been the installation of reflective pavements. These pavements alter the albedo of the surface in order to reflect more shortwave radiation back into the atmosphere thereby limiting the amount of radiation that can be absorbed and released as longwave radiation. Most evaluations of these reflective pavements have been done within a controlled environment examining surface temperature. Those studies that have undertaken field analyses have shown inconclusive results on the pavement’s effects on air temperature and no study has examined human’s ability to sense a thermal difference on these pavements.

This presentation details a multilayered evaluation of a reflective pavement pilot in Austin, Texas. The City of Austin laid down 6.4 lane miles in a neighborhood in southeast Austin in June, 2024. To evaluate the efficacy of the pavement In Situ temperature air temperature and humidity sensors were installed for continuous monitoring within the treated neighborhood and a reference neighborhood directly south of the treated neighborhood. Daily surface temperature profiles were also taken.

The presentation will also show a novel social science approach to understand the efficacy of these pavements on human’s thermal experiences. Specifically, two social science methods were explored. The first is a standard survey methodology to determine the opinions of residents currently living in the treated and untreated neighborhoods on reflective pavement and how it has effected their lives. The second approach is blind study where individuals who did not reside in either the reference or treated neighborhood will walk on and around these pavements and were asked questions to derive if there is in fact a “sensible” difference between the two treatments. This is an ongoing study that will be completed with continued monitoring through the summer of 2025.