Cool Pavement Program
*NEW* 2024 ASU Study
The City of Phoenix Street Transportation Department partnered with the Rob and Melani Walton Sustainability Solutions Service at ASU to evaluate the effectiveness, performance, and potential co-benefits of the new CoolSeal 2.0 pavement coating. In Oct. 2024, City and ASU officials gathered at Burton Barr Central Library to present the results of the research to community members.
Key research findings include:
Cool pavement effectively reduces summer surface temperatures, up to 12°F, compared to conventional aged pavement during the day.
Cool pavement may ultimately reduce long-term road maintenance needs and costs, which could yield substantive economic and environmental benefits.
Cool pavement impacts on air temperature thus far appear to be small but beneficial.
2021 ASU Study
The Phoenix Street Transportation Department and Office of Sustainability announced during a virtual presentation and panel discussion on September 14, 2021 the results of the first year of its Cool Pavement Pilot Program. The program and analysis of the cool pavement process is being conducted in partnership with Arizona State University (ASU).
Year one of the study done by scientists at ASU's Global Institute of Sustainability and Innovation, Healthy Urban Environments, and the Urban Climate Research Center revealed that reflective pavement surface temperatures are considerably lower than traditional roadway pavement.
Cool pavement reflects a higher portion of the sunlight that hits it, hence absorbing less heat. Because of this higher reflection, the coating has the potential to offset rising nighttime temperatures in the region.
The pilot ended in 2021 and cool pavement is now a permanent part of the Street Transportation Department's street maintenance program.
Findings from year one of the study include:
- Cool pavement revealed lower surface temperatures at all times of the day versus traditional asphalt.
- Cool pavement had an average surface temperature 10.5 to 12 degrees Fahrenheit lower than traditional asphalt at noon and during the afternoon hours. Surface temperatures at sunrise averaged 2.4 degrees Fahrenheit lower.
- Sub-surface temperatures averaged 4.8 degrees Fahrenheit lower in areas treated with cool pavement.
- Nighttime air temperature at six feet of height was on average 0.5 degrees Fahrenheit lower over cool pavement than on the non-treated surfaces.
- The human experience of heat exposure at noon and the afternoon hours was 5.5 degrees Fahrenheit higher due to surface reflectivity, but similar to walking on a typical concrete sidewalk.
- Surface solar reflectivity declined over 10 months from a range of 33 to 38 percent to a range of 19 to 30 percent across all eight neighborhoods. Untreated asphalt has a reflectivity of only 12 percent.
About the Program
In 2020, the city selected portions of eight neighborhoods, one in each City Council district and part of the parking lot in Esteban Park, to receive cool pavement treatment. The asphalt coating was applied to areas already in need of pavement preservation. The city then partnered with ASU researchers to conduct scientific tests of the cool paved areas, studying how it performed and how it might be used to mitigate the urban heat island effect.
Scientific data collection during year one of the study included thermal imaging through helicopter flyovers, temperature sensors embedded in the pavement surface, and other advanced instruments to conduct testing across various heat metrics. ASU researchers also developed MaRTy (derived from 'Mean Radiant Temperature'), a specially designed mobile weather station that evaluates the human experience of heat by measuring 3D mean radiant temperature, air temperature, relative humidity, and wind speed and direction. Additionally, a vehicle equipped with air and surface temperature sensors traveled over the treated areas to gather data during four times of the day.
What is cool pavement?
It is a water-based asphalt treatment that is applied on top of the existing asphalt pavement. It's made with asphalt, water, an emulsifying agent (soap), mineral fillers, polymers and recycled materials. It contains no harmful chemicals and is compatible with traditional asphalt.
2024 Cool Pavement Program Locations:
District 5 - McDowell Rd. to Encanto Blvd. from 67th Ave. to 63rd Ave. (QS 13-13)
District 8 - Roeser Rd. to Broadway Rd. from 20th St. to 24th St. (QS 4-32)
2023 Cool Pavement Program Locations:
District 1 - Cactus Rd. to Sweetwater Ave. from 35th Ave. to 31st Ave. (QS 31-21) Moved to 2024
District 2 - Thunderbird Rd. to Acoma Dr. from 44th St. to 48th St. (QS 33-38) Moved to 2024
District 3 - Coral Gables Dr. to Paradise Ln. from 7th St. to 12th St. (QS 35-29) Moved to 2024
District 4 - Oak St. to Thomas Rd. from 16th St. to 20th St. (QS 14-31)
District 4 - Campbell Ave. to Camelback Ave. from 19th Ave. to 15th Ave. (QS 18-25) Moved to 2024
District 5 - Bethany Home Rd. to Maryland Ave. from 31st Ave. to 27th Ave. (QS 21-22)
District 5 - Bethany Home Rd. to Maryland Ave. from 35th Ave. to 31st Ave. (QS 21-21)
District 6 - Indian School Rd. to Campbell Ave. from 40th St. to 44th St. (QS 17-37)
District 6 - Campbell Ave. to Arizona Canal from 40th St. to 44th St. (QS 18-37) Moved to 2024
District 7 - Lower Buckeye Rd. to Durango St. from 83rd Ave. to 79th Ave. (QS 7-9)
District 8 - McDowell Rd. to Oak St. from 32nd St. to 36th St. (QS 13-35)
District 8 - Roeser Rd. to Broadway Rd. from 20th St. to 24th St. (QS 4-32) Moved to 2024
2022 Cool Pavement Program Locations:
District 1 - Yorkshire Dr. to Beardsley Rd. from 51st to 47th Ave. (QS 40-17)
District 2 - Bell Rd. to Grovers Ave. from 40th to 44th St. (QS 37-37)
District 3 - Grovers Ave. to Union Hills Dr. from 16th to 20th St. (QS 38-31)
District 4 - McDowell Rd. to Encanto Blvd. from 19th to 15th Ave. (QS 13-25)
District 5 - Indian School Rd. to Campbell Ave. from 51st to 47th Ave. (QS 17-17)
District 6 - Thomas Rd. to Osborn Rd. from 48th to 52nd St. (QS 15-39)
District 7 - Thomas Rd. to Osborn Rd. from 67th to 63rd Ave. (QS 15-13)
District 8 - Southern Ave. to Roeser Rd. from 19th to 23rd Ave. (QS 3-24)
2021 Cool Pavement Program Location:
District 7 - Roeser Rd. to Broadway Rd. from 19th to 15th Ave. (QS 4-25)
2020 Cool Pavement Pilot Program Locations:
Mayor - Van Buren St. to Roosevelt St. from 12th to 16th St. (QS 11-30)
District 1 - Thunderbird Rd. to Acoma Dr. from 47th to 43rd Ave. (QS 33-18)
District 2 - Carefree Hwy. to Languid Ln. from open space to 27th Ln. (QS 59-23)
District 3 - Shea Blvd. to Cholla St. from 40th to 44th St. (QS 29-37)
District 4 - Van Buren St. to Roosevelt St. from 31st to 27th Ave. (QS 11-22)
District 5 - Campbell Ave. to Camelback Rd. from 55th to 51st Ave. (QS 18-16)
District 6 - Las Palmaritas Dr. to Dunlap Ave. from Central Ave. to 7th St. (QS 26-28)
District 7 - Vineyard Rd. to Southern Ave. from 43rd to 39th Ave. (QS 2-19)
District 8 - Esteban Park: 3345 E. Roeser Rd. - Parking Lot
Contact Information:
Project Hotline: 623-825-3444
pavement@phoenix.gov