I-24 CM/GC Bridge Replacement Over S. Germantown Road

The Challenge

With as many as 100,000 vehicles driving along I-24 each day, heavy traffic was no surprise to travelers in the Chattanooga, Tennessee, area. Traffic had doubled over the past 40 years, contributing to the need for two bridge replacements – the I-24 bridge over Germantown Road and the Belvoir Avenue bridge over I-24.

The Solution

Working closely with the Tennessee Department of Transportation (TDOT), Barge Design Solutions created a plan to encourage a more seamless approach to design and construction, shortening project timelines. The team applied two key approaches to meet the need: the alternative delivery method of the Construction Manager/General Contractor (CM/GC, CMGC) and Accelerated Bridge Construction (ABC) techniques.

The CM/GC process allowed the construction manager to participate in both bridge design processes before completion, paving the way for more accurate cost estimates, constructability assessments, and scheduling. ABC methods were also applied to the S. Germantown bridge design to improve safety and limit traffic disruptions through accelerated scheduling and multitasking.

To support the S. Germantown bridge design, 172 micropiles were drilled more than 160 feet deep into the foundation to resist compressive, uplift/tension, and lateral loads. This method was chosen due to the site's complex karst geology of clay-like soils, small boulders, and complete voids in soil, which were found during geotechnical exploration.

The Result

ABC techniques were the perfect match for the I-24 bridge replacement over Germantown Road. Traditional daily lane closures were reduced from 510 days to only nine, replacing the bridge superstructure in 58 hours for less risk and cost. The CM/GC method – only the third time it has been applied in the State of Tennessee – enhanced collaboration for both bridges, making the process more efficient. Barge earned high accolades for the CM/GC bridge replacement project, receiving a Structural System Honor Award and a People's Choice Award at the 2021 American Council of Engineering Companies of Tennessee Engineering Excellence Awards.