Determined to improve safety and operational efficiency, the Tennessee Department of Transportation (TDOT) is eliminating loop ramps on a 1.6-mile section of Interstate 24 and creating a frontage road in southern Chattanooga to reduce congestion and support new development.

“There are a number of conflict points caused by loop ramps built in the mid-1960s as part of the interstate system,” says Billy Curtis, Project Manager for TDOT. “This project will get all of the traffic off at one point onto this frontage road and then put them back on at one place. This will move the traffic weaves off the interstate and onto the frontage, allowing for smoother traffic flow along I-24.”

I-24 serves as a western gateway to Chattanooga. Approximately 105,000 vehicles travel on this section of the interstate daily. The department began planning for this project in the early 2010s. The updated road will accommodate current and future traffic needs and support area redevelopment.

“This area is being revitalized, and we anticipate an increase in traffic,” says Rae Anne Bradley, Community Relations Officer with TDOT. “We expect this improvement project to help with that additional capacity.”

The interstate, built in the 1960s, passes by the former U.S. Pipe/Wheland Foundry, established in 1936 and closed in 2003, which produced cast iron products including automotive parts. The area has become blighted.

The foundry site is slated for a new 140-acre, $350 million development, according to local news reports. Plans call for multifamily housing, retail and restaurant spaces, offices and a $79.5 million baseball stadium. The city of Chattanooga and Hamilton County are helping to finance the stadium construction, but the majority of funds are coming from private industry.

“We strive to provide the transportation infrastructure that supports economic development,” says Joe Deering, Assistant Chief Engineer for TDOT. “This will improve the safety of the interstate and improve the network of how the system works.”

The new frontage road is being built parallel to I-24 and south of the interstate. In addition to I-24 East, it will connect with U.S. 27, and Broad, Williams, and Market streets with signalized intersections.

“We are eliminating the weave-merge by eliminating conflict points where someone could have an accident,” Curtis says.

Williams Street will become a two-way road, instead of one-way. Long Street will close permanently, with the creation of cul-de-sac to serve existing property owners on that street.

The project has two frontage road bridges, one over Chestnut Street and another over a CSX railroad and a riverwalk area at the old foundry property. The frontage road will have three exit ramps. The former loops pavement will be removed, fill brought in and the ground seeded for grass. I-24 West and U.S. 27 North will continue to be served by loops and ramps.

The project received funding from the state’s Improving Manufacturing, Public Roads and Opportunities for a Vibrant Economy Act.

Arcadis of Chattanooga serves as the department’s design consultant.

Wright Brothers Construction Co. of Charleston, Tennessee, founded in 1961, received the nearly $32 million contract. In addition to Tennessee, the company works in Alabama, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, and Virginia. Crews began construction on this project in October 2020. Utility relocations were needed for telephone and electrical lines.

Near the abandoned industrial site, TDOT developed a mitigation plan to address contaminated foundry sand, which crews removed and disposed of properly.

Wright Brothers brought in fill material to elevate an embankment for bridge abutments on the new frontage road, so it could pass over a railroad. They also built retaining walls.

One bridge is 214 feet long and founded on 14-inch steel pilings. The beams are 63-inch prestressed concrete bulb tee beams. The second bridge is 153 feet long and is founded on 12-inch steel pilings. The beams are 45-inch, type III prestressed concrete I-beams.

The bridges were completed during the project’s first phase and required extensive coordination with CSX. The department had to secure right-of-way over the rail tracks, and the railroad had to approve the lift plans, including how to set the beams. CSX provided a flagman.

Wright Brothers completed the bridges early, which helped to speed up the entire project by only switching traffic once, Curtis says. Crews built the ramp first, then the bridge and once the structure was completed, the department was able to open up the new exit.

Crews also installed more than a mile of storm drains. The pipe sizes range from 18-inch to 36-inch diameter. Crews jacked and bored two 30-inch pipes under I-24, avoiding closures to place the pipes.

The project has consumed more than 29,000 square yards of concrete pavement. Securing enough concrete proved challenging at times due to a nationwide shortage of cement. However, the team saved time on other aspects of the project to ensure the concrete issues did not affect the schedule. Wright Brothers used Topcon total stations during paving.

“Building the road is easy; the hard part is maintaining the flow of traffic during construction,” says Adam Casteel, regional operations engineer with TDOT. “Anytime you are working on an interstate, it’s a dangerous venture.”

Traffic management presented some challenges, particularly when constructing the exit ramps and installing the overhead signage. The department worked with the city to notify emergency responders and drivers in the area at least a week before the closures about what to expect. Most closures occurred at night, with occasional mid-day or weekend daylight closures.

The new I-24 exit ramp at Broad Street opened in October 2022. The project is scheduled for completion in August 2023.

“Once complete, the project will improve connectivity and make it much safer and easier for the regional traffic to access the area,” Deering concludes.