As per Chapter 4 of the FDOT Interchange Access Request User’s Guide published in January 2018, herein referred to as “FDOT IARUG”, this Interchange Modification Report (IMR) re-evaluation has been initiated by the design-build firm based on the proposed design change (New Concept) to the Request for Proposal (RFP) concept and to show that the New Concept satisfies the Safety Operational and Engineering (SO&E) requirements and Federal Highway Administration (FHWA) policy points. The intent of this re-evaluation is to demonstrate that the New Concept operates equal to or better than the RFP Concept (see Appendix A for RFP Concept and New Concept Designs; New Concept design changes described in Section 1.2).
Per Table 4-1 of the FDOT IARUG, the RFP Concept has been used as the basis for comparison when evaluating the New Concept initially developed as Alternative Technical Concept (ATC) 12C during the Technical Proposal Phase. The RFP Concept for I-395 is based on RFP Reference Document RD-01 Concept Plans which includes the Reanalysis I-395 IMR PD&E Traffic Study.
The results from the freeway, ramp and intersection operational analyses demonstrate that the New Concept will operate equal to or better than the RFP Concept and that the proposed improvements will provide the following major operational benefits:
• I-395 Mainline
o Provides direct access to/from Miami Beach and Port of Miami Tunnel by bypassing the entire interchange using the viaduct.
o Combination eastbound (EB) off-ramps to N. Miami Avenue (Ramp B + C) removes any potential for congestion or spill-back from the surface streets onto the I-395 mainline during special events.
• Combination I-395 Westbound On-ramps from N. Miami Ave. (Ramp E + F)
o Improves access from southbound (SB) N. Miami Avenue to westbound (WB) I-395 by combining Ramp F with Ramp E and by providing a new right turn lane off of North Miami Avenue. With this modification, traffic is required to make a single right turn movement at one signalized intersection to gain access to WB SR 836 and/or I-95 instead of crossing seven signalized intersections, making three left turns under the RFP.
o Improves traffic flow of the WB connector by reducing the number of lane changes needed to access northbound (NB) I-95 through the provision of two continuous lanes from just west of MacArthur Causeway instead of from the N. Miami Avenue On-Ramp.
A Safety Analysis Report (SAR) was prepared by FDOT in October 2018 to document the crash statistics for the most recent five years and perform a quantitative safety analysis to predict the safety performance of the RFP Concept. Similar to the operational analysis, the safety performance of the RFP Concept was used as the basis for comparison when performing the quantitative safety analysis of the New Concept. The results from the safety analysis demonstrate that the New Concept will result in an overall a reduction in predicted crashes, a lower crash rate on freeway segments, and equivalent crash rate for ramp/CD segments when compared to the RFP Concept.
Based on the findings of this IMR re-evaluation, the New Concept is recommended for construction as the proposed improvements to the RFP Concept will:
• Enhance operations and safety
• Provide community enhancements
• Meet the two FHWA Policy Requirements
Purpose and Need
Download the Purpose and Need (PDF, 634.1KB)
The Need for improvements is based on a combination of substandard projected traffic conditions, urban planning objectives and the interaction with other planned facility improvements impacting the proposed project area. Project objectives included the study of the following issues: increase capacity to prevent future traffic congestion, improve safety by alleviating existing deficiencies, explore access issues, establish continuity, etc. Current and future developments are anticipated to push the average daily traffic volumes to approximately 200,000 by the year 2040, which will bring the entire corridor to LOS F unless capacity improvements are undertaken. In addition, the present corridor is subject to higher than average heavy truck traffic volumes resulting from the heavy cargo demand associated with the Port of Miami located just east and south of the present limits.