Business can appreciate the look of a successful brief case.
The one Pittman Construction Co., Conyers, Ga., rolled out was perhaps as abbreviated as they come. Using about a dozen weekends, the prime contractor placed 1.3 miles of concrete in the belt buckle of an Atlanta suburban business district. The four-lane State Rte. 140, dubbed the Jimmy Carter Boulevard, carries about 50,000 vehicles on a typical weekday, which includes a significant amount of truck traffic.
The distance of the project might make it look routine, but activity reflected that of an amusement park on a Saturday afternoon. The 1.3 miles covered 29 commercial driveways, nine local street intersections, two state route intersections and a railroad crossing. Approximately 400 businesses were planted in the project limits.
To keep the lines moving, Pittman created new pages in company procedures in the areas of traffic management, public relations, project planning and speed paving.
Speed was the top concern. If crews did not have lanes open by 5 a.m. on Monday, a $5,000 fine was waiting in the company mailbox.
“They wanted to get the new road built as quickly as possible,” Lou Pittman, chairman of the board of Pittman Construction Co., which won an American Concrete Pavement Association award for the job, told ROADS & BRIDGES. “If you didn’t have the lanes reopened you were charged a substantial amount of money, so that got your attention.”
A low-grade base was a main culprit in the latest demise of Rte. 140. The asphalt pavement, which varied in depth from 3 to 8 in., was breaking down enough where the Georgia DOT felt it was necessary to step in.
“There were a lot of accidents in this section,” said Pittman. “The DOT had a lot of lawsuits and there were a lot of potholes developing in the road. They couldn’t keep it maintained.”
GDOT, however, was determined to keep a close watch on time with the next reconstruction job, which led to the stiff disincentive for lane closures. Pittman Construction knew it had to reach full speed right off the starting blocks. Utilities, however, were an immediate concern.
“In this part of the country people don’t know exactly where the utilities are,” explained Pittman. “Some were installed by developers, some by utilities companies. Utility repair crews are hard to get on weekends in the middle of the night, so we really couldn’t afford to hit a gas line and shut the road down.”
Pittman Construction decided to engage in some preliminary work to avoid such a disaster. Backhoes were used to dig down 20 in. alongside the back of curbs to try to get a feel for exactly where the utilities were located. “We located a lot of them that way,” said Pittman.
The prime contractor also found the time to communicate with businesses affected by the construction. A representative was sent into each one of the warehouses to notify managers of the upcoming schedule and to provide a point of contact at Pittman. With the help of the GDOT over 3,500 letters were mailed to businesses, local government agencies, residents and local officials. Releases also were sent to 25 media outlets, and over 20,000 fliers were mailed to locals in the surrounding area and distributed to truckers and motorists at truck stops, weigh stations and rest areas. Changeable message signs also put the public on alert.
“Everyone was very cooperative,” said Pittman. “We had zero trouble and the DOT had zero complaints.”
Trouble, however, has a way of appearing out of nowhere. Pittman Construction battled this phenomenon with a couple of critical backups. The ready-mix producer, Thomas Concrete, had two concrete plants in operation just a mile from the jobsite, and sometimes a third was ready in case of an emergency.
In addition, Pittman Construction took full advantage of its involvement in the asphalt paving industry. One of its own asphalt crews was on call Sunday evening in the event a lane could not open in time for the morning rush hour. Asphalt would serve as a temporary surface until crews could return to the sight the next weekend with the proper concrete.
“We came close one time, but we never had to go that route,” said Pittman.
Pittman Construction also made special arrangements with its quarry, which was operated by Vulcan Materials. The aggregate producer stayed open at night, and when it was closed Pittman Construction stockpiled the material nearby.
Zero was the number to hit when it came to work-zone incidents. Again, reinforcements were called in to handle the demand. The GDOT specified the use of flaggers at each business driveway, and two-way traffic and access to local streets had to be maintained at all times during construction. Pittman Construction used a traffic control coordinator to place and move flaggers during the weekend, and three police officers also monitored the motorists.
“It took a lot of coordinating and planning with this job, a lot more than most jobs,” said Pittman.
Further momentum was built every Thursday, when the prime contractor met with GDOT officials to plan the upcoming weekend activity.
Strong and smooth
A Roadtec milling machine came in to remove the existing pavement, and Pittman Construction used a geogrid reinforcement mat and 10 in. of graded aggregate base to improve the problematic subgrade. Prior to mat placement, a vibratory roller compacted the base.
The concrete mix was designed to reach 2,500 psi in 24 hours and 800 psi flex strength. Using a higher flexural strength reduced the required pavement thickness and limited the removal depth to avoid the utility problems. If the 24-hour strength requirement was not met then a three-day, 3,500 psi level was needed.
Tests were conducted at the ready-mix plants and the jobsite. The GDOT had certified technicians and laboratories at the plants. Additional testing was executed by the central lab’s concrete technical services engineer for the northeast Georgia area. The average flexural and compressive (24 hour) strengths achieved were 792 psi and 3,322 psi, respectively. The average air content was 3-5%, and slump tests came out to 2-2.4 in. Air and slump tests were performed when cylinders were made. A total of four cylinders were made for each day of placement.
As many as 20 ready-mix trucks lined the site during the pour. Pittman Construction used a Gomaco Commander III paver to place the 10-in.-thick pavement. Over 1,500 cu yd of concrete was placed each weekend, with the paver averaging 120 ft per hour. Dowel baskets were anchored into the aggregate base with 12-in.-long hook bars made from No. 4 rebar. Two lanes were closed at a time during the paving process.
According to Pittman, the concrete had a 6- to 8-hour cure period. The challenge of accelerating the process came when workers had to saw the joints to control the cracks.
“The people have to saw it quickly,” he said. “As soon as you could get on it you had to saw it.”
The DOT requirement on smoothness involved diamond grinding as the final surface finish. Pittman Construction had to achieve a ride of 900 mm/km HRI (65 in./mile IRI). A 730 mm/km (55 in./mile) rating was recorded.
“We achieved one of the best rides the state has ever had on concrete pavement,” claimed Pittman. “The more you plan with the owners and the people involved the better off you are.”