APAC Puts New Surfacing Techniques Through Their Paces on DOT Project

The Georgia Department of Transportation is killing two birds with one stone by completing a much needed roadway rehab project on 19.3 meters (12 mi.) of Interstate 20 through downtown Atlanta while trying out a couple of new products manufactured for more efficient roadway resurfacing.

According to DOT Project Engineer Vincent Ogboi, the road was in need of rehabilitation and the DOT wanted to try out these new mixes that promise better durability and drainage, so they began the project in May of 1999. In what the DOT calls a milling and inlay project, the work crews remove the existing asphalt materials and replace it with the first of the new mixes called SMA or stone matrix asphalt. It is then topped with the second of the new materials, PEM or porous European mix. Used together these materials hold the roadway together better, provide for better drainage of liquids off the roadway and reduce rut resistance. The project also includes the resurfacing of the entrance and exit ramps at six intersections along these miles of roadway. APAC and Southeast Bridge Systems have been completing the work for the DOT after a competitive bid process. DOT inspectors are on the scene to ensure the work meets project specifications. According to workers on the project. so far all indications show these new products are going to work well for Georgia’s roadways. “Water runs down through the PEM which is the porous top layer and then runs out through the sides at the second layer [the SMA],” said Dan Krisman, project manager with APAC Georgia’s Chattahoochee Flint Division. “This improved drainage system reduces splash back from other cars on the road and creates more surface contact with the roadway.” The crews are resurfacing both eastbound and westbound lanes of roadway that lies between H.E. Holmes and Windsor Street. The cost of the project totals about $5 million. Because of the heavily-traveled roads in the metro Atlanta area most of the roadwork is taking place during the nights and weekends. As of mid-March, the crews had completed about 60 percent of the project while they face a scheduled completion date of July 2000. By closing two lanes at a time every evening, the crews are given a maximum of 10 straight hours a night to complete the work. Since they are pulling up portions of the roadways, they have to finish the resurfacing before they can reopen the roadway before morning rush hour at 6 a.m. This means a tight schedule and a fast-paced night shift for the workers. “It is a pretty tight timetable,” Ogboi said. “But, so far, we have been able to work with it.” Krisman said they are utilizing additional traffic control devices to try to encourage the public to slow down and they have enacted work zone speed limits of 40 miles an hour. It helps, Ogboi added, that they are able to close two lanes for the entire weekend, starting on Friday evening and reopening them by 5 a.m. Monday morning. But the advantage with this approach is reduced by the fact that there are more travelers on the Atlanta roadways on weekend days. The crews have even had to call off operations on weekend days when major events, such as the World Series, have caused heavier than normal traffic in Atlanta. Another problem facing the DOT crews is Interstate 20 has only four-foot shoulders, which is about six feet narrower than most interstate shoulders, providing little room for crews to move around in and that has been an exceptional challenge to overcome. “There is some tight maneuvering so we are trying to work hard now to finish the project and free up the roads for the public,” Ogboi said. To help the crews better utilize the available roadway space they have been using an Omni 3 screed from Blaw-Knox. This Extend-a-Mat screed gives the crew flexibility to pave wide widths. A cylinder on the machine moves in and out enabling the wider paving. According to Krisman, this piece of equipment is not usually allowed on Georgia roadwork projects, but because of the tight conditions on Interstate 20, the state gave permission to use the machine. The traffic has caused the DOT to be extra cautious with traffic control and better to guide drivers through the construction. “We have had to develop an elaborate traffic control system to shift the traffic to the remaining open lanes,” Ogboi said. Of the 10 hours crews have each night to complete the work about two hours are used for lane closures. “That cuts into our work time considerably,” Krisman said. Besides the narrow shoulders adding an unsafe element to the project the curves of the road create a lot of blind spots so the crews have to use a crash cushion behind them as they work. A police patrol vehicle with flashing lights alerts the public to the work. APAC, which operates in 14 states under several regional offices, has been handling the resurfacing portion of the project and Southeast Bridge Systems has been in charge of changing the joints on the bridges in the area, a portion of the project that equals $1 million. Because the SMA and PEM road materials can not be used in temperatures below 50 degrees, resurfacing had to be put on hold from November to February. During that time, Southeast Bridge Systems stepped in to begin the bridge joint replacement portion of the contract. Besides that scheduled delay, the crews have been fortunate to report excellent weather with very few delays due to cold spells or rain. “We have been pretty lucky,” Krisman said. “We had some great weather last summer to work with.”
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