I-64 at Rieder Road Access Justification Report


Kaskaskia Engineering Group, LLC (KEG) provided engineering services required to prepare an Access Justification Report (AJR) for a proposed interchange access onto I-64 at Rieder Road, adjacent to MidAmerica Airport and Scott Air Force Base, in Shiloh, Illinois.  KEG performed this service as a seamless extension of the St. Clair County Highway Department staff, acting at the direction of, and in full collaboration with, the County Engineer during all facets of the project.  



St. Clair County, Illinois

St. Clair County Highway Department

Project Cost:
$15 Million


The AJR included the development of a comprehensive traffic model utilizing the Synchro software program.  The traffic model included the existing traffic system network, which is composed of rural interstate roadways, diamond interchanges, full cloverleaf interchanges, rural expressway roadways, urban and rural local roadways, and signalized and unsignalized intersections.  The traffic models were developed to analyze the existing roadway network operating conditions, as well as future operating conditions – both with and without the proposed interchange.  The future conditions included extensive analysis of the signalized roadway corridor to improve the flow of traffic along the corridor with changes to the signal phasing and timing based upon the projected traffic volumes.  


The AJR utilized the ISAT crash analysis model developed by FHWA.  As part of the study process, KEG provided feedback on the ISAT model to assist FHWA in the further development of its model.  Access was approved by FHWA within a year of beginning the report.  Access was granted to provide a more direct access corridor to Scott Air Force Base and access to the MidAmerica Airport Industrial Park expansion.  MidAmerica Airport is a joint-use facility sharing services with Scott Air Force Base.  KEG coordinated heavily with the base commander and engineering offices.


The report investigated whether new access to I-64 at or near Rieder Road in St. Clair County was feasible or justifiable by comprehensively studying transportation infrastructure projects that would provide immediate and direct access to Scott Air Force Base.  It also addressed adverse travel time for periods of potential emergencies.  The report analyzed the safety of the existing roadway system should the interchange not be constructed and compared the results to the safety improvements garnered by a new interstate access point.  The study network involved substantial traffic signal network analysis and modeling.

KEG also assisted the County with a financing plan.  The project will be funded by federal, state, and county funds.  





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