In December 2000, Eagle Construction Co. Inc. of Newberry, SC, began widening 5 mi. (8 km) of Ladson Road (between U.S. 78 and Dorchester Road) in Charleston and Dorchester counties, SC.
Expected to be completed sometime later this month, the road will have an additional three lanes as well as a new bridge crossing Eagle Creek. The new road is expected to enhance safety and accommodate the increasing traffic in the area.
“The old two-lane road was narrow with roadside line ditch sections for drainage,” said Mike Kamis, project engineer of Eagle Construction, the primary contractor on the job. “The new five-lane road has a center left-hand turning lane with bike paths and sidewalks on both sides and underground storm drainage.”
Kamis noted that in 1996 the average daily traffic on Ladson Road was 24,600 vehicles per day. The 25-year projection is 38,000 vehicles per day with about 10 percent of that being three-axel trucks and larger.
The state Department of Transportation (SCDOT) designed and is administering the contract for the Ladson Road project. As the prime contractor, Eagle Construction is handling the grading, storm drainage and traffic control of the project.
Sanders Brother’s Construction of Charleston is the paving subcontractor and Cape Romain Contractors Inc., also of Charleston, is the bridge subcontractor. The estimated cost for this state and federally funded project is $18.8 million.
According to Steve Morgan, resident construction engineer of SCDOT, road construction in the Low Country areas of South Carolina often is complicated by drainage concerns because of the extensive wet and swampy conditions.
To alleviate this, SCDOT implemented the soil cement stabilization method in preparation for laying the road.
“This process involved mixing 80 pounds of cement per square yard of service area into the top 16 inches for the final sub grade elevation,” explained Morgan. “This creates a concrete mat for the road to go on. This method is preferred because it avoids digging up all the unsuitable material at the job site, and it also eliminates underdrain in the road.”
According to Morgan, crews laid the nearly 125,000 tons (113,398 t) of asphalt with a 9.5-in. (24 cm) depth in three layers.
“The first layer is AABC –– asphalt aggregate base course. The second layer is a binder course to give the road strength, and the third layer is a service source that seals the road to ensure no water will get though,” Morgan explained. “When there is a lot of subservice water, as is the case in the Charleston area, it is crucial to eliminate under drain in the road.”
Much of the asphalt work was done at night to reduce traffic problems, improve safety during construction and avoid the hot daytime temperatures and high humidity.
Approximately 250,000 cu. yds. (191,138 cu m) of borrowed excavation and 130,000 cu. yds. (99,400 cu m) of excavation were required during the grading process.
Reconstruction of the Eagle Creek Bridge was done in two phases. First, crews constructed half of the new bridge while traffic was shifted to half of the old bridge. After the first half was complete, traffic was shifted onto the new span, and the second half of new bridge was constructed.
The new 90-ft. (27 m) slab bridge has five lanes with sidewalks on both sides. The bridge has 18-in. (45.7 cm) precast concrete piles with poured-in-place concrete pile capes. Because temperature restrictions require that the concrete for the deck be poured under cool conditions, it was done in the early morning hours. After the deck was poured, crews placed the barrier walls, side walks, and 30-ft. (9.1 m) concrete approach slabs.
The excessive amount of water flow in the Low Country area required the installation of five cross lines underneath Ladson Road at various locations. This included two 6- by 4-ft. (1.8 by 1.3 m) precast box culverts.
A third precast box culvert, which crosses Blue House Swamp, measures 12 ft. (3.7 m) wide and 5 ft. (1.5 m) deep. It is one of the largest precast culverts of its kind. Each section of this large culvert required the use of a 175-ton (159 t) crane to set it into place.
The two other cross lines are double 30 in. (76.2 cm) and double 42 in. (10.7 cm) reinforced concrete pipes.
On the job, crews have used a John Deere 862 scraper, a Komatsu D37 dozer, Cat D4 and Cat D5 M dozers, a New Holland (Ford) backhoe, a Komatsu 300 excavator, a Hitachi 300 excavator, Cat 12G and 12 H motorgraders, a Cat 563 s/f roller compactor and a Cat 936 loader.
Eagle Construction has more than 50 employees on the job site daily working up to seven days a week, when the weather permits. When subcontractors are called in, more than 90 workers can be found on the job.