TRANSPORTATION

The Florida Department of Transportation (FDOT) conducted a Project Development and Environment (PD&E) Study in 2008 along I-75 in Sarasota County to determine the ultimate needs for the interstate and interchanges. This study was updated in 2012 as part of a Systems Interchange Modification Report (SIMR). Both reports concluded the Preferred Alternative for the I-75 and Fruitville Road (SR 780) interchange to be Arterial Separation along with adding turn lanes to the on and off-ramp approaches at Fruitville Road. A new interchange reevaluation has developed an additional alternative which is a Diverging Diamond Interchange (DDI). The DDI reduces overall delay along the Fruitville Road corridor, including adjacent intersections as well as the interstate ramp terminals.

The purpose of this Interchange Modification Report (IMR) is to reevaluate the future traffic operations at the I-75 and Fruitville Road interchange, based on the revised population/traffic growth projections and reevaluate the need for the improvements recommended by the PD&E study and the SIMR. The need for this IMR is to identify the most suitable interchange configuration to meet the demands of future travelers while minimizing project costs and impacts, and improving safety for all modes of travel.

The methodology applied for the IMR is documented in the Methodology Letter of Understanding (MLOU), which was approved by the Federal Highway Administration (FHWA) in October 2014. This MLOU was developed in accordance with FDOT Policy No. 000-525-015-h: Approval of New or Modified Access to Limited Access Highways on the State Highway System (SHS), FDOT Procedure No. 525-030-160-j: New or Modified Interchanges, and FDOT Procedure No. 525-030-120-i: Project Traffic Forecasting.

This IMR evaluates two design alternatives:

• The 2012 SIMR recommended Arterial Traffic Separation as the preferred alternative. The Arterial Traffic Separation will be used in place of a No Build scenario and any new alternative must perform as well or better as compared with the SIMR alternative.

• Diverging Diamond Interchange (DDI) alternative.

Based on the results from the evaluation of alternatives, the recommended alternative is the DDI. The two distinguishing features between the SIMR preferred alternative and the DDI alternative are:

1) The increased lane utilization along Fruitville Road approaching I-75 with the DDI configuration.

2) The overall safety improvements for all modes of travel at the interchange intersections.

The SIMR arterial separation continues the existing traffic pattern by positioning all interstate bound vehicles in the right-most thru lanes approaching the interchange. By positioning vehicles destined for northbound and southbound I-75 on opposite sides of the road, the DDI configuration distributes traffic across all of the Fruitville Road approach lanes, increases lane utilization, and decreases travel time along the arterial.

The DDI alternative also provides improved capacity for the southbound on-ramp and requires fewer westbound thru lanes at the Fruitville Road intersections with the southbound off-ramp and Cattlemen Road. The SIMR arterial separation alternative requires more lanes under I-75 and, therefore, a wider and longer bridge over Fruitville Road. The arterial separator also has operational constraints due to the close proximity of the adjacent signalized intersection at Cattlemen Road.

The DDI alternative provides a safer environment for pedestrians, bicycles, and vehicles. The SIMR arterial separation does not provide controlled crossings for pedestrians at the interchange and forces bicyclists to cross multiple lanes of thru vehicle traffic to properly position for the interchange. The DDI alternative incorporates a lower design speed, provides signal controlled crossings for pedestrians at the interchange, positions bicycles west of Cattlemen Road to safely ride through the interchange without crossing multiple lanes of vehicle traffic. The DDI alternative also relocates the on-ramps on the conventional side of the road and removes the loop on-ramps which should reduce the number of rear-end, sideswipe, and “run off the road” type crashes.

Since both alternatives fall within nearly the same footprint, potential environmental impacts are similar between the SIMR alternative and the proposed DDI alternative. In addition, both alternatives require less than ¼ acre of additional right-of-way from three parcels at the intersection of Fruitville Road and Cattlemen Road. However, the DDI alternative has a construction cost savings of $30.3 million when compared to the SIMR alternative.