Ashley-Phosphate Road Widening

"No excuses" clause enforced on $50 million South Carolina highway expansion

by Scott Judy

The South Carolina Department of Transportation made extensive use of incentive/disincentive pay and a "no-excuses" clause on its $50.6 million Ashley-Phosphate Road Widening project in the Charleston area.

Apparently, these tools were put to good use. With the contractor in the final stages and just months away from the original completion date, SCDOT officials are describing the work performed to date as "an A-plus job."

Part of the department's heralded "27-in-7" roadbuilding program - named for its goal of constructing 27 years of projects in just seven - the contract is aimed at relieving significant congestion and related safety problems in the Charleston area.

Ashley Phosphate Road serves as a connector road between Dorchester Road (South Carolina Highway 642), Interstate 26 and Rivers Avenue (U.S. Highway 52). It also serves commuters traveling to and from Summerville, Ladson, North Charleston and Charleston, connecting them to such area destinations as the Northwoods Mall, downtown and the Charleston Air Force Base.

The road also serves commercial and industrial development that lines the project corridor.

advertisement

Leland Colvin, program manager for SCDOT, said the most recent average daily traffic count for Ashley-Phosphate was 64,800, with a rate of 77,700 vehicles anticipated within 20 years. Traffic on Interstate 26, for which Ashley-Phosphate is a major interchange, was reported as 115,000 and is expected to escalate to 182,000 by 2025.

Timeline

Banks Construction Co. of Charleston Heights, S.C., a firm that specializes in asphalt paving, won the general contract in August 2002. Work started two months later with substantial completion set for this summer.

In between those milestones, there have been numerous others tied to incentive/disincentive pay under the project's "no-excuses" bonus provisions. First, the contractor team had 60 days from the time it received its Notice to Proceed to complete construction of Northside Drive. For every day this part of the contract was completed ahead of that 60-day schedule, Banks Construction would receive $6,500 per day in incentive payments.

The contractor had 45 days from the start date to construct substructures for the South Ashley Phosphate Road and U.S. Highway 52 Bridge, and a $20,000-per-day incentive to finish ahead of schedule.

Another section involving both bridge work and widening allowed 563 days and provided a potential $12,500-per-day incentive/disincentive. Widening yet another stretch of Ashley-Phosphate allowed a 623-day schedule and offered a potential bonus of $6,500 per day. Widening of the final section and total project completion was scheduled for 1,017 days, with a $10,000-per-day early completion incentive.

Colvin said Banks Construction earned incentive pay on all of the milestone sections.

Project Details

Colvin described the contract as "actually two projects in one." The first part was to widen approximately 4 mi. of Ashley-Phosphate from Dorchester Road to Rivers Avenue. The second was building the major interchange with I-26.

The interchange portion consists of replacing and widening two interstate overpasses, constructing an on/off ramp for I-26 East and adding "collector-distributor" lanes serving Ashley Phosphate and U.S. 52 for I-26 West.

The contract also called for replacing the U.S. 52 overpass with a new three-lane bridge and replacing the existing five-lane Ashley Phosphate overpass with a 10-lane structure.

The remainder consists of widening Ashley Phosphate Road. This widening effort was "pretty simple" because the existing road was already five lanes wide - two lanes in each direction with a median lane, Colvin said. In short, there was plenty of room to add two lanes and accommodate associated traffic shifts.

"We just reduced the lane size and went out and widened half of the road, shifted traffic back and then went back and widened the other half," he added. "With five lanes, that's not too difficult."

Banks started work at the I-26 interchange area, located at the eastern end of the project. Colvin said the team had to hustle through this section as quickly as possible. This section featured a $20,000-per-day incentive/disincentive.

The interchange area required significant soil stabilization, a situation that normally might have been addressed with a surcharge of soil material left on the area for an extended period of time. Due to the area's traffic volumes, the group simply couldn't wait that long.

"We put some heavy incentive/disincentive on that end of the project to where we could get the contractor in and out," Colvin said.

DOT and project designer Earth Tech Inc. of Raleigh, N.C., opted for a variety of ground modification techniques, including vibratory concrete columns and vibratory stone columns.

"We had 16,236 lin. ft. of vibratory concrete columns and 20,000 lin. ft. of vibratory stone columns," Colvin said. Installation of these substructures provided the necessary support for the new overpass structure.

The proximity of the interchange work to a popular shopping center actually caused unanticipated changes.

"We're close to the Northwoods Mall, and what we did not account for in our traffic-control plan was pedestrians as we phased the bridge," Colvin said. "We had to tweak the design to include a pedestrian path during the construction phasing on the bridge there at I-26."

Partnering and Progress

As this project nears completion, Colvin said everything has gone well. He praised the partnering initiative undertaken by the project team, which was led by Banks Construction and also the project's construction engineering and inspection firm, Davis & Floyd.

"The biggest thing was just the partnership," Colvin said. "We got together with the city, the county, fire department, police department, all of the utilities and our contractors and had periodic partnering sessions. So it's gone very well."

Project Team:

Owner: South Carolina Department of Transportation
General Contractor: Banks Construction Co., Charleston Heights, S.C.
Designer: Earth Tech Inc., Raleigh, N.C.
Construction Engineering and Inspection: Davis & Floyd

Useful Sources:
http://www.dot.state.sc.us/Projects/Ashley/default.shtml