Tennessee Department of Transportation—Diverging Diamond Interchange at SR 66

Tennessee’s Sevier County is known as the gateway to the Great Smoky Mountains National Park, the most visited national park in the country (about 10 million visitors a year). Motorists typically access the area via I-40 to State Route 66 at Exit 407, which had an interchange incapable of meeting the needs of so many visitors. Traffic was very congested near the exit, creating safety concerns. TDOT came up with the plan for a Diverging Diamond Interchange based on the design’s ability to accommodate left-turning volumes, cut the number of conflict points at intersections and minimize the number of lanes required between interchange ramp intersections. The completed $19.9 million project now allows for the huge influx of visitors to the area, good for the economy, and keeps those motorists safe.Panorama View of the Sevier County DDI.jpg