Several years ago, the Tennessee Department of Transportation (TDOT) engaged GS&P to implement an upgrading of Briley Parkway from I-40 to I-65 (9 miles total). The job included widening the route anywhere from four to 12 lanes, replacing numerous bridges and upgrading eight interchanges. But the interchange at Briley Parkway and the western end of Two Rivers Parkway posed a more challenging problem.
Five important arteries intersect at this point: Two Rivers Parkway; Two Rivers Court, which continues along the scenic bank of the Cumberland River; Gaylord Drive, providing access to Gaylord Headquarters; and the entrance and exit ramps to Briley Parkway. In addition to the complex intersection, two major concerns were expressed to the GS&P team: maintaining traffic flow and clearly communicating access to the five different arteries. In the mind of GS&P principal-in-charge Michael Flatt, P.E., this five-way transition from the highly traveled Briley Parkway to Two Rivers Parkway seemed well suited for a roundabout. However, this aid to smooth continuous traffic flow, common in the UK and Europe, is seldom seen in the southeastern United States causing some reluctance to use this design.
Throughout the project, the GS&P team continued to continually suggest that the roundabout would be a good solution. Eventually their suggestions found an attentive audience. Although construction was well under way, TDOT directed GS&P to go forward with the roundabout design. The original deadline would still be met, leaving the team only six weeks to complete the design changes. GS&P quickly and expertly accommodated not only the roundabout but also the newly approved Metro Greenway Trail which runs straight through the heart of the intersection.
Safety was a big concern for TDOT as there was great chance of a driver entering the wrong direction ramp. Without the roundabout design it would have been extremely difficult to inform the motorist of the abrupt artery connections. The roundabout design allows travelers to easily navigate the turns using simple signage pointing out each entry and exit path.
As design work on the roundabout and its connectors proceeded, a sunken pathway was designed for the Greenways trail as it passed under the freeway ramp. This preserved the continuity of the trail, as individuals were shielded from the visual intrusion of both the traffic and the physical engineering of this busy intersection.
The single-lane urban roundabout opened on time, smoothly and safely guiding traffic without a signal, and Greenways patrons now follow their trail undisturbed. Today, TDOT is pleased with the decision to be part of this innovative solution. Every aspect of the project was completed and operational on time, and on budget.