TRANSPORTATION

This Interchange Modification Report (IMR) for the Interstate 10 (I-10) and SR 85 (South Ferdon Boulevard) interchange in Okaloosa County covers the documentation requirements agreed upon in the Methodology Letter of Understanding (MLOU).

The purpose for conducting the IMR study is to document the impacts and evaluation of the operational traffic conditions for the proposed modifications. This IMR study aims to improve the safety, Level of Service (LOS), and traffic operations at the Interstate 10 (I-10) and SR 85 interchange. The alternatives evaluated as part of this study are listed below:

• No-Build Alternative: This alternative represents the existing diamond interchange configuration with the FDOT committed roadway improvements. This No-Build alternative also includes the proposed new interchange (I-10 at CR 4/Antioch Road) about 2.6 miles west of SR 85.

• Interim-Build Alternative (Diamond Interchange): This alternative represents the Transportation Systems Management and Operations (TSM&O) improvements identified under SR 85 (I-10 EB Ramp to Hospital Drive) Interchange Improvement Project with financial ID: 443672-1, and SR 85 3R (Resurfacing, Rehabilitation and Reconstruction) project with financial ID: 441548-1. Following is a list of improvements identified under each financial ID:

Financial ID: 443672-1: SR 85 (I-10 EB Ramp to Hospital Drive) – Interchange Improvement
1) Extend the northbound right turn lane at the intersection of I-10 eastbound Ramp
2) Extend the southbound left turn lane at the intersection of I-10 eastbound Ramp
3) Extend the northbound left turn lane at the intersection of I-10 westbound Ramp
4) Extend the southbound right turn lane at the intersection of Mirage Avenue
5) Add a second northbound left turn lane at the intersection of I-10 westbound Ramp and widen the pavement to allow for an additional receiving lane
6) Add pavement at along I-10 westbound off ramp to accommodate for a westbound right turn lane and re-stripe the existing westbound right turn lane as a second westbound left turn lane
7) Add a northbound travel lane between I-10 eastbound ramp and Hospital Drive

Financial ID: 441548-1: SR 85 (SR 123 to I-10) – 3R Project
1) Modify the full median opening at Southcrest Drive to a directional median opening.

Based on recent conversations with FDOT District Three, the 3R project also will include the addition of pavement along the south leg of the I-10 eastbound ramp to accommodate a third receiving lane.

• Ultimate Build: This alternative includes the widening of SR 85 between SR 123 and I-10 to six lanes. This roadway widening project would entail the reconstruction of I-10 and SR 85 interchange. This IMR study evaluates two configurations for I-10 and SR 85 interchange, along with additional intersection improvements at the intersection of SR 85 at John King Road, and, SR 85 at Mirage Avenue. The two interchange configurations being evaluated under this alternative are:
? Improved Diamond Interchange
? Diverging Diamond Interchange (DDI)

Improvements at adjacent intersections include:

SR 85 at John King Road: Add westbound right turn lane for a total of two right turn lanes.

SR 85 at Mirage Avenue: Add westbound left turn lane for a total of two left turn lanes, add westbound right turn lane and restripe the existing shared through-right as through lane. Add a southbound left turn lane for a total of two left turn lanes and restripe the southbound right turn lane to shared-through lane and extend the turn lane length.

Traffic Operational analysis was performed for the no-build alternative and the interim-build alternative for the opening year 2024 and design year 2044. All the ramps and freeway mainline segments are anticipated to operate at or above the acceptable LOS target under the no-build and interim-build alternatives. Under the no-build alternative, the I-10 eastbound ramp at SR 85 and the intersection of SR 85 at John King Road are anticipated to operate below the adopted LOS target during the opening year 2024, p.m. peak conditions. Under the interim-build alternative, the TSM&O improvements recommended at the I-10 and SR 85 intersection and along SR 85 corridor will improve the operating conditions in comparison to the no-build alternative. Except for the SR 85 at John King Road intersection, all other signalized study intersections are found to operate at or above the adopted LOS targets during the opening year 2024, a.m. and p.m. peak conditions.

The interim build alternative analyses for design year 2044 conditions, shows a need for additional improvements along SR 85 corridor. SR 85 (SR 123 to I-10) is identified to be funded through construction (widening from four lane to six lane) in the Okaloosa-Walton TPO’s 2040 Cost Feasible Plan. The PD&E Study for SR 85 (SR 123 to I-10) is scheduled to commence in fiscal year 2019. Traffic operational analyses for the Ultimate Build alternative during the design year 2044 conditions show that all the signalized study intersections, ramps, and freeway mainline segments would operate at or above the LOS target during the design year 2044 conditions.

The SR 85 PD&E Study will further evaluate I-10 and SR 85 configuration for the horizon year and will include the supporting Interchange Modification Report (IMR) for the preferred alternative.