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79th Street Retaining Walls Rehabilitation

Modjeski and Masters has been selected to perform the design of new retaining walls for the Metrolink light rail overpass at 79th Street in East St. Louis. The original walls were constructed in 2000 as a part of the Metrolink extension into St. Clair County. The walls began to show signs of failure just five years after their original construction. Following an in-depth investigation of the wall and subsequent preliminary design report, Metro solicited assistance to rehabilitate the walls. M&M was selected to review the recommendations of the preliminary design report and determine a cost-effective and viable rehabilitation to extend the useful life of the walls for the foreseeable future.

The existing walls support the light rail on embankment which runs parallel to and between St. Clair Avenue, a minor arterial, and Schoenberger Creek. The walls include a series of mechanically stabilized modular block walls built using 8-inch by 18-inch extruded concrete blocks. The existing walls have a maximum height of approximately 16 feet and run parallel to the Metrolink alignment, wrapping under the structure at the 79th Street overpass. Just under 2,000 feet of retaining wall will be rehabilitated.

M&M will review the conceptual plan; explore viable cost-effective alternatives; conduct a hydraulic study for nearby Schoenberger Creek; perform the retaining wall design, including slope stability analysis; prepare plans, specification and cost estimates, including traffic control plans; and provide construction support services.

Wall Geometry
Total Retaining Wall Length Approximately 2,000 feet
Maximum Retaining Wall Height 16 feet
Tracks Supported 2 tracks