SR 408/SR 417 Interchange Improvements

The SR 408/SR 417 interchange is one of the largest and most heavily traveled interchanges linking northeast Orlando and downtown. The interchange suffered severe congestion during peak travel times and was confusing to motorists. To address these issues and improve regional mobility, the Orlando-Orange County Expressway Authority (OOCEA) contracted with RS&H to design a true system-to-system interchange.

Improvements to the interchange included widening SR 408 from six to eight lanes and adding a new two-lane ramp from southbound SR 417 to westbound SR 408, as well as from eastbound SR 408 to northbound SR 417. Also included are two long bridges, a 1,600-foot-long complex steel box girder flyover, and a curved prestressed concrete beam bridge.

The interchange features numerous innovations, including five overhead signs that meet newly adopted guidelines in the Manual on Uniform Traffic Control Devices. Tourists visiting Central Florida’s attraction will benefit from these massive signs, which are some of the first in the state. In addition, nearly 13,000 linear feet of noise barriers were installed, including the first transparent bridge-mounted noise barriers in Florida.

The highly complex interchange improvements were successfully completed ahead of schedule while maintaining the interchange flow of 97,000 vehicles per day on SR 408 and 74,000 vehicles per day on SR 417.

Water Resources
RS&H designed 20 ponds to treat and attenuate stormwater runoff from the SR 408/SR 417 interchange and minimized pond earthwork by utilizing existing pond geometry and side slopes when possible. Existing pond outfall structures were also used when possible to reduce construction cost, and 12 existing ponds were retrofit to accommodate the new water quality and quantity requirements from the increased amount of impervious area. The team proposed eight new ponds within the right-of-way, as well as two temporary ponds, which were necessary for maintenance of traffic purposes. Four concrete box culverts that convey the E-40 and L-10 Canals through the interchange were extended to accommodate the widened roadway, and several other cross drains throughout the project were extended outside the clear zone due to the proposed widening.

The existing and proposed ponds were designed and analyzed using PONDS Version 3.2. The storm sewer conveyance system, cross drains, and side drains were designed using GeoPak Drainage 2001.