State Route 417 From US 17/92 to Interstate 4
By Roger Trevett, Parsons and Gary Kuhns, GEC
ASHE Central Florida Section

SR 417 from US 17/92 to Interstate 4 recently was opened to traffic. The project is of major importance to the Central Florida transportation network. Travelers now can drive from Interstate 4 near Celebration to Interstate 4 in Sanford without interruption. This project has many years of history. The Seminole County Expressway Authority selected three consultants for design in the early 90s, PBS&J, DRMP, and URS. The design was progressed to 60% and turned over to Florida's Turnpike. The plans then were completed, and the project was permitted. Three CEI firms were selected, HNTB, GAI, and URS in the late 90s. Construction started in 1998. The three contractors awarded contracts were Modern Continental, Eby, and Granite Construction. The contractors worked within a very aggressive schedule to ensure the opening in 2002. A large increase in traffic along the existing sections of SR 417 from travelers seeking relief from Interstate 4 in Seminole County already has occurred.

The project included interchanges at US 17/92, CR 46A, Rinehart Road, and Interstate 4. Several sideroads, such as Airport Road, required relocation. At the Interstate 4 interchange, the project included CD roadways to handle the weave movements from the SR 46A interchange to the south and from the SR 46 interchange to the north.

One of the most challenging issues was the presence of very deep, soft, organic soils (muck and peat) within the CR 46A interchange. These deposits extended to depths of up to about 100 feet in some locations and had caused very large settlements of CR 46A over the years. To construct the new interchange, these soft soils were improved by consolidating them with a surcharge fill 12 feet in height prior to roadway construction. The surcharge was monitored using settlement plates, slope inclinometers, and pore water pressure transducers to determine the safe rate at which fill could be placed and when the surcharge's effect was completed. Reinforcing plastic geogrids also were used to provide embankment slope stability on the very soft soils. Ground settlements greater than about 10 feet were recorded at some locations prior to stabilization of the surcharge and successful completion of the interchange.

This important project is a major victory for the Central Florida transportation community. Representative John Mica, along with Metro Plan, helped secure funding in order to accelerate construction. Great cooperation took place among the Seminole County Expressway Authority, Florida's Turnpike, FDOT Fifth District, the designers, the CEI consultants, and the contractors. ASHE would like to congratulate everyone that contributed to this very critical and successful project.