I-65 / SR 109 Interchange & Widening Project

ROBERTSON & SUMNER COUNTIES, TN

TRANSPORTATION

Palmer Engineering provided design and survey services for the widening of approximately 1.72 miles of I-65 from the Kentucky state line in Sumner County, Tennessee, including the development of a new Partial Cloverleaf (ParClo-B) interchange at SR-109. The project was designed to improve traffic operations, safety, and regional connectivity along one of the nation’s most significant north-south interstate corridors.

As part of the improvements, a new collector-distributor (CD) road was added along southbound I-65 to eliminate weaving conflicts between the existing Welcome Center and the proposed SR-109 interchange ramps. The project also included the relocation of approximately 2.11 miles of SR-109 on a new alignment featuring a four-lane divided rural section transitioning into a five-lane urban roadway near the intersection of SR-41 (US 31W). Improvements along SR-41 included roadway widening, turn lanes, curb and gutter sections, and the design of new traffic signals at key intersections.

Additional improvements included a new auxiliary lane along northbound I-65 between the proposed SR-109 interchange and the existing Kentucky Welcome Center to improve merging operations and traffic flow.

Palmer Engineering’s responsibilities included additional field and bridge surveys, roadway alignments, side road relocations, hydraulic analysis, right-of-way calculations, traffic signal design, pavement marking plans, maintenance of traffic plans, erosion prevention and sediment control plans, roadway quantity calculations, and stream relocation and mitigation coordination. The project was let to construction in 2015 and completed in 2020.

As a key regional transportation corridor connecting Nashville and Louisville and serving communities throughout Tennessee and Kentucky, the I-65 improvements support long-term economic growth, interstate commerce, and improved mobility for both commuters and freight traffic.

Unique Aspects

Opportunities

Regional Mobility: Improved traffic flow and safety along a critical interstate corridor connecting Tennessee, Kentucky, and major national freight routes
Economic Growth: Enhanced interstate access and transportation efficiency to support regional commerce, development, and daily commuting
Interchange Modernization: Introduced a new ParClo-B interchange and collector-distributor road system to improve operational efficiency and reduce conflict points
Corridor Enhancement: Upgraded SR-109 and SR-41 infrastructure to better accommodate future traffic demands and local growth
Challenges

High-Traffic Corridor: Designed improvements along one of the region’s busiest interstate corridors while maintaining traffic operations throughout construction
Complex Traffic Operations: Addressed weaving movements and merging conflicts between interchange ramps, the Welcome Center, and adjacent roadway connections
Multi-Roadway Coordination: Coordinated improvements across interstate, state, and local roadway systems, including multiple signalized intersections
Environmental Coordination: Developed erosion prevention, stream mitigation, and permitting plans while minimizing impacts during roadway expansion
Successes

Safety Improvements: Reduced operational conflicts through the addition of auxiliary lanes, collector-distributor roads, and upgraded interchange geometry
Capacity Expansion: Increased roadway capacity and improved traffic efficiency for both regional commuters and interstate freight traffic
Integrated Corridor Design: Successfully combined interstate widening, interchange reconstruction, roadway relocation, and signal improvements into one coordinated project
Project Delivery: Supported successful completion of a major transportation improvement project from design through construction completion in 2020