Design-build, a method of construction used by the ancient Greeks on buildings such as the Parthenon, is relatively new in American construction practices. Abandoned by modern architects and builders, the process is resurfacing in projects throughout the county.
The design-build process is playing an important role in the widening of I-85 in North Carolina. As an extremely efficient process, in which engineers prepare the design while construction is under way, design-build eliminates bidding periods and redesign. This generally reduces construction times, lessening the impact on traffic.
Blythe Construction Inc., headquartered in Charlotte, NC, along with its design partners, LPA Group and KCI Associates, both located in North Carolina, obtained the contract for the I-85 project, which extends south of the U.S. 29/NC 49 connector in Mecklenburg County, NC, to the Speedway/Concord Mills Boulevard in Cabarrus County, NC.
The I-85 design incorporates an accelerated schedule and several important innovations. According to Brian Webb, Blythe project manager, the design-build process allows contractors a platform for incorporating innovative ideas into the construction process, allowing managers more input to improve the projects as they progress.
Ronald Graham, resident engineer for North Carolina Department of Transportation (NCDOT), noted the capacity of I-85 no longer met the needs of the community and needed to be widened.
“For this project, NCDOT choose the design-build method because it offered to get the product back to the public quicker, and at a lesser cost,” Graham said.
“During the design-build process on I-85, Blythe suggested building one bridge on the U.S. 29/49 connector to carry traffic over the interstate. The original traffic plan, presented by the state, showed U.S. 29/49 traffic merging onto I-85 from under the interstate. This meant that two bridges would need to be built on I-85 to go over U.S. 29/49,” explained Webb. “This design-build process reduced the bridge schedule by six months. Additionally, traffic on I-85 and on the U.S. 29/49 connector was not disrupted, accelerating the construction process. Traditional construction would not have allowed such a change in plans.”
“By building a bridge on U.S. 29/49, the state will save money by eliminating the need to widen the proposed I-85 interstate bridges at a later date,” continued Webb. “The maintenance costs for bridges over the interstate is considerably less than bridges on an interstate.”
The Blythe Construction bridge plans also allowed for a controlled demolition of the existing northbound bridge without risking traffic safety and environmental contamination.
The project is divided into three sections: northern, middle and southern. Construction began in February of 2003, with May 2004 as an anticipated date of completion for the northern section. Completion of the middle and southern sections is slated for December 2004.
The project involves widening approximately 8.3 mi. (13.4 km) of I-85 from south of the U.S. 29/NC 49 connector in Mecklenburg County to the Speedway/Concord Mills Boulevard in Cabarrus County. I-85 south of the U.S. 29/NC 49 connector to I-485 will be widened to eight lanes with a 22-ft. (6.7 m) median with a concrete barrier. I-85 from I-485 to the Speedway/Concord Mills Blvd. will be widened to three lanes northbound and four lanes southbound.
In the future, designers are planning the widening of all of I-85 to eight or more lanes. These proposed additional lanes would be added to the median of I-85. One auxiliary lane per direction — for a total of 10 lanes — will be added to the outside of I-85 between several interchanges within the project limits. In addition to the proposed widening of I-85, the existing U.S. 29/NC 49 connector entrance ramp onto southbound I-85 will be reconfigured from a left-hand entrance ramp to a right-hand entrance ramp. Cameras, fiber-optic cable, vehicle detection systems and overhead dynamic message signs, which will be connected with the Metrolina Regional Transportation Center, also will be installed along I-85.
Blythe Construction handled all milling, grading and paving for the project, and the company owns all the equipment being used for these processes.
Milling was done using a Roadtec RX 50 milling machine. According Phil Addison, Blythe asphalt operations manager, all the milled material was hauled to the Blythe asphalt plant, located in Concord, NC, where it was processed to be recycled back into new paving projects.
Excavators used for grading include a John Deere 330, a Komatsu PC3400, several Caterpillar 322s, and a Caterpillar D5 and D6. A Komatsu D65 bulldozer, several Caterpillar and Ingersoll-Rand vibratory rollers and two Caterpillar IT24 loaders also were employed. Crews also used three motorgraders, including two Caterpillar 14 Gs fitted with global position satellites (GPS), which automatically computes the position of the blade in relation to the grade from the satellite input.
“Utilization of the GPS equipped graders, greatly speeds up the grading process,” Webb said.
Grading required approximately 450,000 cu, yds. (344,000 cu m) of dirt to be moved. According to Webb, the widening of the highway to the inside reduced earthwork by 70,000 cu. yds. (53,500 cu m).
“Because we limited construction to about the same footprint as the old roadway,” said Webb, “we were able to reduce the amount of grading needed and minimize the environmental impact to the area, including 404 feet of stream.”
During paving, crews used a Blaw-Knox 5510 track machine with a 10 to 20 ft. (3 to 6 m) screed. Addison estimated that between 350,000 to 360,000 tons (317,500 to 326,600 t) of asphalt would be used before the job is complete.
The Lane Construction Corporation, a heavy-highway contractor headquartered in Meriden, CT, was hired to furnish and place the concrete over the top of the permeable asphalt drainage layer (PADL). According to Thomas Malchak, Lane superintendent, crews will place 185,000 cu. yds. (141,000 cu m) of concrete, with a depth of 14 in. (35.6 cm), using two paving spreads — 12 ft. (3.6 m) high by 24-ft. (7.3 m) wide — over the top of the 4 in. (10.2 cm) of PADL on the roadway.
“The PADL improves drainage under the pavement,” Malchak said. “It is essential to prevent joint failure over the life of the concrete paving.”
The placing of the concrete began in late July and will take approximately 13 months to complete.
For more information, visit www.i85widening.org.