Several years ago, MDOT discovered that a scour hole had developed near a bridge pier. Over the years, the water continued to scour the hole around the bottom of the pier, which endangered the footing of the bridge. MDOT did remedial work to ensure the vitality of the bridge.
The bridge, along with the others that are being replaced, was built in the early 1960s. Besides suffering the typical wear and tear, the bridge has an older design and is narrow with a minimal shoulder. Therefore, anytime MDOT had to do work on the bridge or there was an incident, the driving public experienced major traffic delays.
To accommodate the new alignment, which is about 100 feet to the east, the team is constructing a 2-mile-long road on the northbound side of I-55.
“Before we decided to have a new alignment or a detour, we did a cost analysis,” says Tony Sheffield, a District Construction Engineer for MDOT. “A new alignment was chosen because the land outside of the existing right of way, which was needed for the new alignment, was owned by the Army Corps of Engineers, so we did not have to buy right of way.”
Along the new alignment, the finished grades were significantly higher, requiring the team to place large amounts of earthwork and asphalt.
Instead of tearing out 2 miles of concrete on the southbound lanes, the contractor – W.G. Yates & Son Construction Company of Fort Worth, Texas – performed a crack and seat operation. To do this, they used a piece of equipment from Impact Roller Technology, the Impactor 2000.
The machine is designed to be “…efficient at delivering, high-volume, deep-soil compaction, and various high-production pavement breaking functions.” The website adds that the machine has a 19,000-pound cam-shaped drum and can deliver an estimated 22,000 feet pounds of energy with each blow. Sheffield says, “The machine busts up the pavement, and then a roller pushes it back to form a rigid pavement.”
The new bridges will range from 694 to 802 feet in length. They will be 48 feet in width, while the previous bridges were just 28 feet in width. There was a minimal shoulder on the old bridges. Wide trucks would often hit the rails, leaving MDOT to make repairs. The average daily traffic count on this section of I-55 is 32,000 vehicles, with 22 percent of those being commercial trucks.
The new bridges will have full-width shoulders and wider lanes. “Widening the bridges will make them safer and easier to maintain,” Sheffield says.
Unlike the typical pile driving, which goes quickly, it was a lengthy process on this job. “When the team drove the piles to the initial elevation that the engineers advised, they didn’t achieve bearing,” says Kris Pierce of MDOT, who is serving as the Project Engineer. “The team had to keep going down and eventually left the pile at a deeper elevation for 30 days while the ground stabilized and the pile tightened up and provided to the needed bearing.”
Another challenge the contractor faced was site access. “The creek can swell especially when it rains, so getting equipment and materials from one side of the creek to the other is challenging,” says Mitchell Ward of MDOT, who served as the Project Manager. The contractor built a road, but it was washed away. The equipment was endangered, but not damaged.
“They have a very good ability to schedule their work and always follow through,” Sheffield says. He adds that they’re organized and keep the DOT well informed, which makes it easier to respond to the public.
Pierce seconded the notion, “They plan well and make it easy for inspectors to know what to look for.”
Not only are they excellent at planning, but they are also safety-oriented. “Safety is their number one priority, and one way this is clear is that everyone on the job has stop work authority,” Ward says.
W.G. Yates was selected based on their low bid. The project has a budget of $52.5 million. It’s slightly over budget due to the piling challenges. Funding for the project is being split 80/20 between the federal and state government.
The project began in June 2022 and is scheduled to be complete this fall. As of now, the team does expect to finish on time despite the issues with the piling. While the piling was an issue, the team shifted to other work. The contractor’s organization skills made the shift relatively seamless.
Soon, commuters along I-55 in Tate County will have wider safer bridges. For MDOT, they will have a bridge that requires little maintenance or rehab.