Rising waters during the past year have forced a delay in the McCain Creek Bridge replacement project in Shreveport, La. Originally scheduled for completion in April, the project is now expected to take until mid-June.
“Anytime you’re working in the bottom of a creek there’s a possibility of flooding,” explained Project Engineer Michael Murphy, Louisiana Department of Transportation & Development. “The job called for demolishing two existing bridges and replacing them with one 15 by15 by 420 ft. (4.5 by 4.5 by 128 m) quadruple barrel box culvert.”
The overall bid for the project was approximately $16.3 million, with a project bid cost of $12.3 million. More than 9,000 cu. yds. (6,880 cu m) of concrete had to be used for the new construction, which is backfilled with 80,000 cu. yds. (61,164 cu m) of embankment material. Each box quadrant was built individually, using a cofferdam/dewatering system.
Completed in 1979 as part of the I-220 bypass, the structures have seen their share of wear and tear. The average daily traffic for I-220 is approximately 28,000 vehicles. The McCain Creek bridges are located within the limits of the future I-49/I-220 interchange ramps.The eastbound bridge was approximately 42 ft. 9 in. (13 m) wide by 352 ft. (107 m) long and the westbound bridge was approximately 42 ft. 9 in. wide by 320 ft. (97.5 m) long.
“They required modifications to accommodate future ramp traffic and because the bridge required a considerable amount of maintenance, it was decided that it was more cost effective to replace it with a four barrel 15 by 15 ft. reinforced box culvert. Another advantage to the box culvert verses a bridge was an overall lower maintenance cost,” Murphy said.
“This project is set up in four stages — the southwest corner, southeast corner, northeast corner and, finally, the northwest corner,” Murphy continued. “The contractor chose the option of building a cofferdam to work in. The sheet pile wall in the middle of the creek was incorporated into the box culvert structure. Due to the limited space of construction and the fact that the contractor couldn’t work on too many items at once, we primarily had one inspector at all times. During periods of concrete pours, major earthwork and asphalt operations, we would increase the number of inspectors to four or five. Even though the contractor provides his own quality control, we provide oversight over the contract, specs and plans and also perform acceptance testing in the field.”
“Our inspectors, no matter what job, always have to be mindful of safety issues” added Murphy. “The biggest concern was how motorists would handle the traffic configuration for the project.”
Diverting Traffic Safely
The project is on a four-lane divided highway. For the first two stages of the project, the entire eastbound roadway was shut down and the eastbound traffic was swapped to the inside lane of the westbound roadway, while westbound traffic was moved to the outside lane of the westbound roadway. For the last two stages, the entire westbound roadway will be shut down and both eastbound and westbound traffic will travel on the eastbound side. So far, traffic has reportedly handled the shift well.
Approximately 700 ft. (213 m) of drainage pipe ranging between 36 and 72 in. (91.4 and 182.8 cm) has been installed as part of the replacement. Once that task was finished, paving, striping, drainage and erosion control issues had to be addressed.
Danny Gosserand, a supervisor for LaMay Group LLC, Livonia, La., explained, “We planted grass, using about 1,200 pounds of seed and 5,000 pounds of fertilizer, and went through about nine tons of hay which was distributed on the slopes.”
“When you have that much runoff coming off the edge of the road, you take great pains to keep the slope at a certain grade,” Gosserand continued. “We used a Ford tractor for seeding and fertilizing, then blew rounded bales of hay using a John Deere four-wheel drive with a haybuster attached to the back of the larger tractor. The ’teeth’ shredded the hay and formed a blanket of it that was distributed on the slopes. A hydro-sealer was also used to prevent hay loss during periods of rain.”
Other subcontractors on the project included Protection Service Inc., Southern Synergy, Thomas Grinding Inc. and Benton & Brown L.L.C., a producer of hot mix asphaltic concrete.
“We furnished and installed the sub-grade layer, class II base course — in this case, crushed stone base from a quarry in Arkansas — as well as cold planing and superpave asphalt paving on this project,” explained Benton & Brown estimator Alvin Miller. “We performed the initial asphalt paving and cold planing for the initial traffic shift approximately one year ago. The first permanent roadway pavement that replaced the removed bridge occurred this year when we began and completed the installation of the 12-inch deep sub-grade layer, which consisted of cement-treated dirt material back in February. The equipment used included a Cat RM500 recycler, a vibratory pad foot compactor, a pneumatic rubber tired roller, a Cat 140M motor grader and water trucks.
Crews began the class II base course in early March. It took more compaction effort to get density on this stone than usual, but requirements were met.
“We used a Cat PM201 milling machine to remove the old asphalt on the existing shoulders that we were to resurface adjacent to the existing portland cement concrete pavement,” Miller said. “As far as the superpave asphaltic concrete installation, we milled up and re-laid about 66 tons of asphalt mix at the west tie-in, to provide a smoother tie-in between the new and existing pavements. The main paving equipment used was a Cat asphalt paver, along with a Roadtec material transfer device (MTV) and smooth drum vibratory compactors. The MTV is used to keep the mix from segregating during the dumping process.
“The biggest challenge for our company on this phase was the tie-in of the new asphalt surface to the existing roadway surface. Tie-ins are always a bit difficult, and this project was no different. ”
He added, “The weather has been one of the biggest challenges on the whole project, because unfavorable conditions prohibit construction operations. However, between the end of February and mid-March, we only lost two days to rain. That was really a blessing, considering the entire month of January and early February were so wet and cold.”
The general contractor for the McCain Creek Bridge replacement is Eutaw Construction Company Inc., Jackson, Miss.
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