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Jefferson County – I-57/I-64/IL 15 in Mt. Vernon Interchange Project
The Illinois Department of Transportation has performed a Preliminary Engineering and Environmental Study of alternatives for improvements to the Interstate 57/64 at Illinois 15 interchange in Mt. Vernon. The project study area was as follows: I-57/64 split (approximately 0.8 miles north of Illinois 15) to north of Veteran’s Memorial Drive and on Illinois 15 from Davidson Avenue to 42nd Street.
The detailed study explored transportation issues within the project area, while integrating community concerns through an open and comprehensive planning process. Mt. Vernon is at the crossroads of two major interstates, as well as a major arterial route. The north-south I-57 connects Chicago and Memphis (via I-55 in Missouri), the east-west I-64 connects St. Louis and Louisville, and Illinois 15 is an east-west Illinois State highway. Previous engineering studies completed for the I-57/64 and Illinois 15 interchange have shown the need for improved access to and from I-57/64 and Illinois 15 by increasing capacity and reducing accidents. The final study was approved in September of 2023.
Upon completion of the project study, Phase II began. Phase II consists of refining the design and developing contract plans and land acquisition. Recommended improvements for Illinois 15 at I-57/64 include removal and replacement of the existing structure, requiring the reconstruction of the existing interchange at Illinois 15 and improvements to the intersection of Potomac Boulevard/45th Street. The recommended interchange for Illinois 15 at I-57/64 interchange is a diverging diamond, which offers reduction of conflict points for improved safety and traffic flow through the interchange. All the proposed improvements were carefully considered to address operational, geometric, safety and capacity deficiencies, while minimizing impacts to the environment and existing property owners. This recommendation also provides a cost-effective solution.
A section of Illinois 15 will be realigned at the I-57/64 interchange. The purpose of the realignment is to reduce the skew of Illinois 15 at the interstate and improve safety at the interchange. The proposed improvements will increase operational performance and reduce the number of anticipated crashes. Accommodations will be provided for bicycles and pedestrians.
Preparation of contract plans and land acquisition are proceeding. The project will move to Phase III, construction, in spring 2025 and is expected to take 24 to 36 months to complete. Construction will occur in stages to allow the I-57/64 ramps and Illinois 15 to remain open to traffic with the exception of short-term and/or overnight ramp closures at exit 95. Marked detours will be provided for any closures.
Exhibits from the public meeting depicting the proposed interchange and associated improvements can be found on the project meeting website: https://projectmeetingonline.com/mt-vernon-interchange-at-il-15/.
Resources:
Check out this video from the Federal Highway Administration on how a diverging diamond interchange operates: https://www.youtube.com/watch?v=eLAwwl3EtN4.
Mt. Vernon approved project report, exhibits and appendices - September 2023
