The Florida Department of Transportation (FDOT) has conducted a Project Development and Environment (PD&E) Study to evaluate capacity improvements along the segment of Interstate 75 (I-75) -State Road (SR) 93- that extends from just north of SR 52 in Pasco County to just south of County Road (CR) 476B in Sumter County, Florida. The length of this segment is approximately 20.8 miles. The design year for the improvements is Year 2030.
Study Purpose and Need
The objective of this PD&E Study was to document the engineering and environmental analyses that were performed for this project so that the FDOT and the Federal Highway Administration (FHWA) could reach a decision on the type, location, and conceptual design of the necessary improvements of I-75 to accommodate future traffic demand in a safe and efficient manner. This study documented the need for the improvements as well as the procedures utilized to develop and evaluate various improvement alternatives. Information related to the engineering and environmental characteristics, which are essential for the alternatives analysis, was collected. Design criteria were established and preliminary alternatives were developed. The comparison of alternatives were based on a variety of parameters utilizing a matrix format. This process identified the alternative that would have minimal impacts, while providing the necessary improvements.
The PD&E Study also satisfied all applicable requirements, including the National Environmental Policy Act (NEPA), in order for this project to qualify for federal-aid funding of subsequent development phases (design, right of way acquisition, and construction).
The segment of I-75 (SR 93) that extends from north of SR 52 in Pasco County to just south of CR 476B in Sumter County has been evaluated for widening from a four-lane to an eight-lane freeway. The need for this improvement was established after consideration of the following factors:
- Evaluation of the current and future contribution of I-75 in accommodating regional travel and its importance in providing system-wide linkage within the overall roadway network.
- Review of the federal and state policies regarding I-75 and, where applicable, study of the comprehensive plans and the long-range transportation plans of the local governments involved in this project.
- Assessment of current and future social and economic demands.
- Study of the interrelationships of I-75 with other modes of transportation.
- Evaluation of the quality of traffic operations in the study area for the design year assuming that no capacity improvements will be implemented along this corridor (No-Build Alternative).
- Analyses of the traffic safety statistics for the period between 1999 and 2003.
- Comparison of the geometric characteristics of I-75 with current design standards as well as research of records for structural deficiencies along the project.
The proposed improvements for this project were developed based on traffic analyses, review of local government plans, evaluation of several alternatives –including the No-Build Alternative–, and input collected from the various project stakeholders through the Public Involvement Program efforts. To make best use of the FDOT and the FHWA funds in implementing these improvements while ensuring that efficient and safe traffic operations are provided along the project at all times, it is recommended that the “preferred” alternative is constructed in two phases. A brief description of the improvements included in the “preferred” alternative and their construction phasing follows below.
Phase 1 Improvements: In Phase 1, the mainline of I-75 will be widened to provide six lanes by constructing a 12-foot-wide travel lane in each direction of I-75 within the median, along the existing inside lane. The widening of I-75 will be accommodated within the existing right of way. The remaining median width, after construction of the inside lanes, will for most of the project length be 40.0 feet wide; 24.0 feet less than the standard minimum median width for this type of facility. A design variation will be required to implement this design.
This phase will also include the replacement of the existing I-75 bridges over SR 50 to accommodate the need for additional lanes along SR 50. The proposed replacement bridges over SR 50 and the I-75 profile approaching the bridges will be at a higher elevation to meet current design standards. These elevation changes will require the ramps to be re-constructed and lengthened in order to “tie in” to the new roadway in a safe and efficient manner. With the exception of widening the existing structures at Croom Rital Road and the Withlacoochee River, it is not anticipated that other bridges in the study section will be affected during this phase of construction. Phase 1 also includes right of way acquisition for construction of stormwater management facilities, as required, to accommodate the “ultimate” improvements of I-75. It is estimated, based on the current traffic growth trends, that these improvements will be sufficient to accommodate the traffic demands along I-75 until the year 2021.
Phase 2 Improvements: In Phase 2, the mainline of I-75 will be widened to provide eight-lanes by constructing an additional travel lane in each direction of I-75 along the existing outside lane. With the construction of two new outside lanes, the border width will be reduced from 94.0 feet to 82.0 feet, which will require a design variation. In addition, to accommodate this widening and provide adequate horizontal clearances, all minor roadway overpass bridges with the exception of Church Road will need to be replaced. The widening of I-75 will occur within the existing right of way.
Phase 2 also includes the construction of the improvements at the interchanges of I-75 at CR 41 and SR 50 as described below.
- CR 41 Interchange: The existing northbound ramps in the northeastern quadrant will be replaced with a “diamond-type” interchange ramp arrangement similar to the existing SR 50 ramps. The new northbound diamond off-ramp will provide for additional deceleration and queuing of vehicles at the ramp terminal. Additional right of way will be required in the southeastern quadrant for construction of the new off-ramp.The southbound ramps in the southwestern quadrant will be reconstructed with a partial clover configuration that will meet current design standards and provide sufficient queuing for vehicles at the ramp terminal with CR 41. Additional right of way will also be required in the southwestern quadrant to accommodate the expanded footprint of the new ramp design.In order for the interchange to operate at an acceptable level of service, CR 41 will need to be widened to provide a four-lane rural typical section from east of the northbound ramps to west of the southbound ramps. The improvements will also include the relocation of the existing access roads in the northwestern and southeastern quadrants of the improved interchange. The access road intersections will be relocated further from I-75 along CR 41 to allow for expansion of limited access right of way limits to meet current standards.
- SR 50 Interchange: A direct “flyover” ramp will be constructed to accommodate the motorists who are traveling northbound on I-75 and are destined to westbound SR 50, thus removing this traffic entirely from traveling through the signalized intersections of the termini of I-75 northbound and southbound off-ramps at SR 50. To avoid access and relocation impacts to several businesses along SR 50, the “touchdown” point of the ramp is proposed within the SR 50 median. The northbound exit ramp terminal will be constructed approximately 3,900 feet south of SR 50 to allow for sufficient distance for deceleration and decision time for the movement to either the westbound flyover ramp or the eastbound at-grade ramp. Additional right of way will be required along the east side of I-75 to accommodate this new northbound ramp design.