AEI provided Phase I design and final Phase II design of the reconstruction of the KY 348 Interchange with the Julian M. Carroll Purchase Parkway (JMCPP) in Marshall Co. AEI also provided an Interchange Modification Report (IMR). The project provided necessary improvements at the JMCPP and KY 348 to be interstate compliant as part of the future I-69 corridor and add ramp capacity to KY 348, due to recent development. The existing interchange loop ramps – designed for a toll station and stop condition - did not meet current standards for acceleration and deceleration tapers, turning radii, and superelevation rates.
AEI was initially tasked with Phase II design based on prior Phase I work that recommended a standard Diamond Interchange maintaining the existing four lane facility and existing depressed median. In addition, the existing KY 348 Bridge over the JMCPP was to be replaced due to proposed widening of KY 348 and inadequate vertical clearance. Following AEI’s review and discussion with the Project Team, AEI was directed to revise Phase I alternates to meet the project needs while reducing construction cost. AEI provided four Partial and one Full Diamond Interchange for consideration. These alternates included:
1. Alternate 1 - Partial Cloverleaf Interchange that constructs Ramps on the south side of KY 348 and provides an acceleration lane on existing northbound loop on ramp and a deceleration lane on the existing southbound loop off ramp.
2. Alternate 2 - Partial Cloverleaf Interchange that constructs Ramps on the north side of KY 348 and provides an acceleration lane on existing southbound loop on ramp and a deceleration lane on the existing northbound loop off ramp.
3. Alternate 3 - Partial Cloverleaf Interchange that constructs Ramps for the on ramps from KY 348 and provides deceleration lanes on existing loop off ramps.
4. Alternate 4 - Partial Cloverleaf Interchange that constructs Ramps for the off ramps from the Julian M. Carroll Parkway and provides acceleration lanes on existing loop on ramps.
5. Full Diamond Interchange - Provide ramps at all four legs of the interchange. The ramps utilize portions of the existing loop ramps to reduce construction costs.
AEI provided preliminary plans, profiles, critical cross sections, bridge structural analysis and cost estimates for each alternate. it was determined that cost for the full diamond interchange was not significantly different than the partial diamond options due to the length of accel/decel ramps needed to meet standards. Also, it was decided to leave the existing KY 348 Bridge in place and modify the grade of the JMCPP to provide the required vertical clearance.
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