Low Country, South Carolina — Charleston County Public Works is responsible for a variety of tasks on a daily basis, including the maintenance of Lowcountry roadways. And in recent years, they have gone above and above to protect our roads while also providing environmental advantages to those who travel on them every day.
Residents drive on the roads every day, and each vehicle adds to the wear and tear. MacKenzie Kelley is concerned about this.
“At Charleston County, we’re unique in that we manage not only county-owned roads, but also all 16 municipalities across the county, as well as state secondary roads,” said Kelley, engineering manager for Charleston County Public Works. “So essentially that’s every public paved road in the county except for the interstate system.”
That’s 1400 kilometers of road to maintain.
“We have a pavement preservation program using a product called rejuvenation,” Kelley told me. “So it’s basically like a Thompson Seal coat for your hardwood deck. It will assist preserve and protect the road from the sun and water.”
In recent years, they have begun utilizing an updated product called Plus TI on some roadways. It works as a photocatalytic rejuvenator.
“When the sun hits it, the electrons start getting excited and they’re grabbing that pollution that goes over, and knocking it down into a nitrate turned into a fertilizer on the side of the road, essentially, is a way to think of it,” Kelley told me.
So far, about 50 miles have been covered with this so-called road sunscreen.
“Our first pilot project we did down in the Rosemont in the neck area, that’s an identified heat island,” Kelley told me. “And, being just next to the freeway, we believed this product would be a huge asset to that neighborhood. We’ve also driven Mikkell Drive on James Island.”
Next up are International Boulevard and South Aviation near the airport, but treatment will be added to an additional seven to ten miles over the next year.
The project data demonstrates that Plus TI is working, with their pilot project successfully extending the life of the road by five years, reducing harmful vehicle pollution by about 40%, and eradicating almost all microplastics on the road.
“If we could get right at the source, especially before it gets to the waterways, that that’d be huge and great environmental benefit,” Kelley claimed.
The modified roadways also shed four times more heat than the untreated ones.
“We’ve identified large heat islands along roadways is a main source, so we can go ahead and get that heat out of here and help with the cooling in Charleston, especially in that summer heat,” according to Kelley.
With temperatures rising swiftly in the summer, any relief is welcome. Kelley and her team collaborated with people from SC Sea Grant, The Citadel, MUSC, and many other organizations on this study, however they were unable to obtain some of the data they desired.
“I think there’s just too many variables with the heat moving or the wind moving,” Kelley told me. “It’s not as controlled as a lab setting, at its foundation. So we’re hoping to see anything in the field, but it’s difficult when you only treat one route in a huge area.”
Even without this data, the benefits exist, but they come at a price.
To give you a sense of price, basic rejuvenator costs roughly $1 per square yard, whereas Plus T-I costs between $2 and $2.50 per square yard. Products like these are covered by the transportation sales tax and the county transportation committee, which together generate approximately $10 million per year.
“I have to remember as a pavement manager, our goal first is to preserve the roads,” Kelley told me. “So I can’t go out and treat everything with this substance, so I want to be responsible with taxpayer money, so conserving roads is our first priority. And then the second purpose is to see whether we can incorporate these environmental benefits.”
Fortunately, the Charleston County Council has made this a priority.
“Last year county council adopted in their strategic plan that we would continue to improve or increase by 5% every year of the photo catalytic rejuvenator,” Kelley recalled.
Their mission is to help build roads that not only get us where we need to go, but also improve the environment.
