I-75, I-24 Interchange Modifications

In 2019, the Tennessee Department of Transportation (TDOT) selected Thompson Engineering to provide construction engineering and inspection (CEI) services for the I-75 and I-24 interchange modification in Chattanooga, Hamilton County, Tennessee. The existing I-75 and I-24 corridor is heavily traveled and serves Tennessee and Georgia. Both I-75 and I-24 provide a direct connection to downtown Chattanooga, Lookout Mountain, and other area attractions; I-24 also serves as a direct link between I-75 and I-59.


Within the study area, I-24 is primarily a six-lane, controlled-access facility that is separated by a concrete barrier wall and has a right-of-way width of approximately 500 ft. The area of I-75 within the study area is primarily an eight-lane, controlled-access facility that is separated by a concrete barrier wall and the right-of-way varies from approximately 300 to 600 feet in width.


The project consists of the modification and reconstruction of the I-75 interchange at I-24. The roadway improvements begin at the Georgia state line and extend on I-75 to a point approximately 455 feet south of the existing I-75 bridge over the CSX railroad, and to a point just west of the I-24/Spring Creek Road bridges. The project includes the widening of the I-75 roadway to include an additional lane in each direction, widening of all interstate-to-interstate ramps to three lanes, modifications to I-24 ramps to enter and exit I-75 from the right side, and modifications to the Ringgold Road and Welcome Center traffic pattern. Individual features include 13 bridge replacements and/or widenings, 22 retaining walls including one noise wall along with associated grade, drain, base, paving, roadway lighting and ITS activities. Other special features include numerous environmental commitments that are ecology, noise, hazardous material, etc. related. In addition, a Traffic Management Plan minimizes impacts to the I-75 Welcome Center as well as sets specific limitations on lane closures and total closures.


The project was awarded to the Design Build Team of Barge Design Solutions and C.W. Matthews in the amount of $132.6 million with an estimated completion date of June 1, 2021.







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