Johnson Creek Bridge, Roadway Job Proves ’Not Run-of-the-Mill’

Fri September 03, 2004 - Southeast Edition
Brenda Ruggiero

Visitors to Fripp and Hunting Islands near Beaufort, SC, will find their destination a little easier to reach next year when a bridge replacement project is completed.

The South Carolina Department of Transportation (SCDOT) awarded the contract to replace the U.S. 21 bridge that crosses Johnson Creek with a wider one capable of meeting current traffic needs and those of the future.

The prime contractor for the $5-million project is Republic Contracting Corp., under the direction of project manager John W. Brodie. The notice to proceed was given on Oct. 27, 2003, and completion is set for Sept. 30, 2005. Most of the funding is provided by the federal government.

Republic’s Antonio Ragos said that as of July 16, the project was within 7 percent of work versus time, which is considered to be within schedule.

The bridge and the roadway are to be constructed in two stages to maintain existing traffic, which presents a bit of a challenge. The new bridge will be 648 ft. (197.5 m) long and 44 ft. (13.4 m) wide and will replace the narrow bridge built in 1939.

Ragos noted that the quality review for this project was held on June 10 by the SCDOT Quality Management Team in Columbia. The rating achieved was 2.92 of a possible 3 score.

Greg Cook is the regional manager of subcontractor U.S. Group Inc., which is handling the approaches to the bridge.

He explained, “For safety reasons, they wanted to decrease the radius around the curve going to Fripp Island, and they wanted to widen it for traffic. Republic is building the physical bridge, but we’re doing … all the traffic control, the erosion control and all the earthwork. It’s not your run-of-the-mill roadway where you just go and pave.”

Cook added that one of the most interesting and challenging aspects of this particular job has been the mechanically stabilized earth wall.

“It’s actually something relatively new to the DOT,” he said. “They use a wire mesh basket and geogrid. The geogrid holds the earth in place, and then you come up in lifts and bring the wall up. The weight of the dirt is holding down the geogrid, and that’s holding the wall up –– sort of supporting itself as opposed to driving sheet pile or something like that.”

This type of work was a new experience for U.S. Group, according to Cook.

“We subcontracted that kind of work out in the past, and we did it in-house this time, so that was a challenge –– a learning curve.

“We also had a very specific earth work spec on that for granular soils,” he said. “We had to travel a pretty long ways to find the dirt, and we ended up value engineering that job with the DOT and having it a little bit redesigned by my own consultant in order to change the spec on that earthwork and to build the wall.”

As with many projects in this area of South Carolina, weather conditions factor into the challenges.

“We’ve had a lot of challenges with keeping the erosion control measures in place, because the wind is fierce through there, and it actually blows the silt fence down,” said Cook, noting that the group has worked very closely with the geotechnical department to overcome some of the unusual processes and challenges.

Currently, approximately 3,000 cu. yds. (2,293.6 cu m) of earth have been moved, with 1,300 cu. yds. (993.9 cu m) of unclassified excavation. Approximately 115 cu. yds. (87.9 cu m) of concrete has been used, along with 18,000 lbs. (8,164.7 kg) of reinforcing steel. Approximately 2,609 lineal ft. (795.2 m) of prestressed concrete piles and 1,051 lineal ft. (320.3 m) of prestressed concrete beams have been used as well.

According to Ragos, there are currently seven people assigned to the job, including one supervisor, one surveyor, one foreman, one crane operator and three laborers.

Major equipment used on the project includes a Manitowoc 4000W crane with a 150 ton capacity, a Caterpillar D3 6 dozer, an ICE 1070 pile hammer and a Caterpillar backhoe.