In both the rural and urban areas of the U.S., roadway potholes are a fact of life. In Cabarrus County, N.C., the Rosco RA-300 spray patcher helps put an end to potholes while stretching the county’s highway department budget.
Cabarrus County is growing rapidly and its county and state highways are heavily traveled. The county has a population of 150,000 within its 364-sq-mile area, and the state maintains approximately 1,000 miles of road. The county is located just northeast of Charlotte, N.C., along the I-85 corridor.
“We began by renting the pothole patching unit in September 2004,” said Janice Hampton, county engineer with the state DOT Cabarrus Maintenance Unit. “We quickly found that the patches were long-lasting, filled more quickly and the process was more economical.” Cabarrus County maintains its patching crew for larger potholes when subgrade problems may exist, as well as areas where paving is the correct method of repair.
The county later purchased an RA-300 spray patcher , and today operator Clyde McManus patches approximately 40 potholes each day. “When we receive calls from the public about a pothole or our crew leaders notice them during their travels, the potholes go on a list and we do our best to patch it the next day,” McManus said. “When we know where the potholes are, it takes no time at all to put the patches in place.”
The four-step spray injection process begins with the pothole being cleaned of rock, debris and moisture using a high-volume blower. Next, a tack coat of hot emulsion is applied to the area in need of repair. Third, a mixture of aggregate and hot emulsion is blown into the hole to fill the depression. Lastly, a top layer of dry aggregate is applied and traffic is able to flow immediately.
McManus performs this process without ever leaving the safety and comfort of the cab in his climate-controlled RA-300 . A state-of-the-art joystick permits him to control all the patching functions with fingertip ease.
“I was familiar with the old method of pothole patching,” McManus said. “The Union County state maintenance unit was having success with spray-injection patching. I trained under them and it only took me a few months to really become proficient with the patcher. Now, it’s second nature to drive down the road monitoring road conditions and stopping along the way to repair a pothole quickly and move on.”
The Rosco RA-300 patcher has a 17,900-lb operating weight with a 400-gal capacity heated emulsion tank and a 5-cu-yd aggregate storage capacity. The front-mounted articulating boom makes positioning over the area to be repaired easy via the in-cab joystick control. Amber strobe lights make drivers aware of the unit, and a large rear-mounted arrow board directs traffic movement while patching.
Spray-injection patching is one of the fastest and most economical methods of pothole repair, according to the Strategic Highway Research Program. The 1992 research also found it to be one of the most effective and long-lasting repair techniques.
Safety is one of the greatest benefits, according to Hampton. “Our primary concern is the safety of our employees and travelers. The spray-patching truck provides us with a safe method to address potholes in high-traffic, safety-sensitive areas.”
According to Hampton, the quick and economical spray-injection patching process has worked well for Cabarrus County.