MDOT's SR 15 expansion project in Union County, Miss., is ahead of schedule. The 6-mile stretch is heavily traveled, serving factory workers in the furniture capital of America. Challenges include endangered species conservation, gas and transmission lines, rock excavation, and material management. The $59 million project, financed by federal and state funding, is being handled by Talbot Brothers Contracting Co. and is expected to be completed by fall 2025, a year and a half ahead of schedule.
Thompson Engineering photo
The primary element of the construction is the addition of two parallel lanes along 6 mi. of Highway 15 in Union County. Upon project completion, the existing highway will serve as the northbound lanes, while the additional roadwork will cater to southbound traffic.
In the spring of 2012, the Mississippi Department of Transportation (MDOT) scheduled a project in Union County in the northeastern part of the state.
However, two other projects came up that the state determined were more necessary. So, there was a lack of funding for the original project, and it stalled out. More than a decade later, the State Route 15 4-lane highway project was under way.
Road Is Highly-Traveled
The north/south State Route 15 runs the entire length of Mississippi and is more than 300 mi. long. The 6-mi. section runs in Union County between Pontotoc and New Albany, Miss., in just two lanes. A traffic count was conducted on a nearby section of SR 15 — the ADT was 14,000. That's the highest ADT for a two-lane route in the state.
"Many people travel on SR 15 for 30-40 miles to get to work," said Brandon Smithey, resident engineer of MDOT.
Smithey, who is overseeing the project, added that a significant portion of the traffic is factory workers. Northeast Mississippi is the self-proclaimed furniture capital of America. The area is home to more than 30 furniture factories.
The traffic patterns mean southbound experiences the lion's share of traffic during the morning commute, and northbound is jammed in the evenings.
"While there are relatively few accidents on the roadway, when they do happen, they wreak havoc," Smithey said. "It's hard to get around when an accident occurs, and drivers could be forced to take a multi-mile detour."
The other roads in the area are primarily rural, typically narrow, and not well-paved.
Two More Lanes
The primary element of the construction is the addition of two parallel lanes along 6 mi. of Highway 15 in Union County. Upon project completion, the existing highway will serve as the northbound lanes, while the additional roadwork will cater to southbound traffic.
Once the team completes the new lanes, MDOT will switch traffic to the new alignment and work on another project element. The existing lanes also are being repaved.
Less than 1 mi. of the current highway is being completely redone. The team is restabilizing the subgrade with cement and new lifts of asphalt due to the deterioration of the existing asphalt pavement. On the north end of the project, the team is creating a new alignment for the northbound traffic to cross the King Creek bridge.
The project will impact three existing bridges. One bridge is being widened to match the width of the larger highway. The team also is installing two new bridges (northbound and southbound). The 302-ft.-long and 82-ft.-wide bridge will cross 110-ft.-wide King Creek.
Note that the team had to redesign the first .5 mi. of the project from what it was in 2012. The original design was to have a divided 4-lane to cross King Creek, but there was a conflict with a natural gas pipeline valve station in the planned centerline for the southbound lanes.
The estimate for relocation of the valve station was $12 million, and the 2012 estimate for bridge, grade and drain for that 6-mi. section of road construction was $11 million. Due to that significant cost, MDOT went back and made the decision to extend the 5-lane out of the New Albany city limits and to cross King Creek to just past the pipeline. This allowed MDOT to proceed within existing ROW and construct the newly proposed alignment at a significant cost savings to the department.
King Creek is home to the Mississippi silvery minnow (note: it can be found in other states and waterways as well), which is considered an endangered species.
"Because we're dealing with an endangered species, we have to be extra cautious," Smithey said. The team made sure to be as efficient as possible. They also cleared and stabilized the creek bank. We were able to strip the banks, do some minor grade adjustments to banks, place geotextile and riprap, and place super silt fence to stabilize that in permanent position in just four days to minimize exposure."
Roadway Challenges
By all appearances, most of the stretch of highway sits in an idyllic location. There are trees and fields in the vicinity. However, there is more to the area than meets the eye.
Within the project limits is a TVA transmission line. The team had to be aware of the line while swinging the cranes. They put tension on the line to get it out of the way.
There's also a 30-in. natural gas transmission line.
"We were told if we hit the line, it would blow a hole 200 feet deep into the ground," Smithey said.
There's $1.5 million worth of natural gas in the line. At its closest point, the line is just 15 ft. from where the crew works.
The gas company insisted that MDOT and the team monitor the line to ensure the vibration was not at a level that would cause damage. Ultimately, the gas company paid to have an independent contractor measure the PPV vibration. Smithey noted they measure vibrations as the team drove piling. The team never ran into an issue related to the gas line.
While inputting borings for new road alignment, the team encountered an A4 type material. This is a type of sand that has lots of clay.
"When it's dry, it's fine to work with, but when it's wet, it's not suitable for usage as it becomes spongy," Smithey said. "It's a material that needs sunshine and wind as it takes twice the time to dry as regular dirt.
He noted that the material may be unusable depending on the weather at the time of use.
So, why work with the fickle material? It's cheaper than borrow dirt.
Another issue the team ran into was the level of rock excavation. Originally, they expected to remove 1,700 cu. yds. of rock. However, they encountered two veins of rock and had to remove 54,000 cu. yds. of rock. This led to a cost overrun of $2 million.
Team, Budget, Schedule
The construction budget for the widening of SR 15 is just below $59 million. The team is half a million over budget.
"We may end up a bit higher due to asphalt, which is running higher due to inflation and grade control," Smithey said.
The project is being financed via the traditional 80/20 split between the federal government and state government.
Talbot Brothers Contracting Co. Inc. serves as the project's general contractor. The company, headquartered in Nesbit, Miss., (northwest of the project location) has worked with MDOT many times, particularly in north Mississippi. Smithey has worked with Talbot on multiple occasions. He said they are reasonable to work with, responsible, responsive and they keep a project moving.
The SR 15 project began in August 2023. The contract allowed the contractor 595 working days and for the project to conclude in spring 2027. However, Smithey expects the contractor to complete the project in fall 2025.
How has Talbot advanced the project so they can complete it a year and a half early? Talbot brought in a second contractor to help with dirt work. Plus, there was a drought in the area in 2023.
While that has many harmful effects, it was good for construction.
"Talbot worked until Christmas 2023 and only had one or two rain days and, even then, they got work done," Smithey said. "They were ready to go as the project let as they had machines delivered to the area before the job began."
When the project is completed, those who travel the heavily trafficked route will enjoy quicker, more reliable travel times. The route also will also be safer. Finally, SR 15 will offer four lanes of traffic from Pontotoc to New Albany and connect 4-lane U.S. 278 to 4-lane I-22. CEG
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